WorldWideScience

Sample records for allometry chemical equilibrium

  1. Bioaccumulation Potential Of Air Contaminants: Combining Biological Allometry, Chemical Equilibrium And Mass-Balances To Predict Accumulation Of Air Pollutants In Various Mammals

    Energy Technology Data Exchange (ETDEWEB)

    Veltman, Karin; McKone, Thomas E.; Huijbregts, Mark A.J.; Hendriks, A. Jan

    2009-03-01

    In the present study we develop and test a uniform model intended for single compartment analysis in the context of human and environmental risk assessment of airborne contaminants. The new aspects of the model are the integration of biological allometry with fugacity-based mass-balance theory to describe exchange of contaminants with air. The developed model is applicable to various mammalian species and a range of chemicals, while requiring few and typically well-known input parameters, such as the adult mass and composition of the species, and the octanol-water and air-water partition coefficient of the chemical. Accumulation of organic chemicals is typically considered to be a function of the chemical affinity forlipid components in tissues. Here, we use a generic description of chemical affinity for neutral and polar lipids and proteins to estimate blood-air partition coefficients (Kba) and tissue-air partition coefficients (Kta) for various mammals. This provides a more accurate prediction of blood-air partition coefficients, as proteins make up a large fraction of total blood components. The results show that 75percent of the modeled inhalation and exhalation rate constants are within a factor of 2 from independent empirical values for humans, rats and mice, and 87percent of the predicted blood-air partition coefficients are within a factor of 5 from empirical data. At steady-state, the bioaccumulation potential of air pollutants is shown to be mainly a function of the tissue-air partition coefficient and the biotransformation capacity of the species and depends weakly on the ventilation rate and the cardiac output of mammals.

  2. Computing Equilibrium Chemical Compositions

    Science.gov (United States)

    Mcbride, Bonnie J.; Gordon, Sanford

    1995-01-01

    Chemical Equilibrium With Transport Properties, 1993 (CET93) computer program provides data on chemical-equilibrium compositions. Aids calculation of thermodynamic properties of chemical systems. Information essential in design and analysis of such equipment as compressors, turbines, nozzles, engines, shock tubes, heat exchangers, and chemical-processing equipment. CET93/PC is version of CET93 specifically designed to run within 640K memory limit of MS-DOS operating system. CET93/PC written in FORTRAN.

  3. Equilibrium Chemical Engines

    OpenAIRE

    Shibata, Tatsuo; Sasa, Shin-ichi

    1997-01-01

    An equilibrium reversible cycle with a certain engine to transduce the energy of any chemical reaction into mechanical energy is proposed. The efficiency for chemical energy transduction is also defined so as to be compared with Carnot efficiency. Relevance to the study of protein motors is discussed. KEYWORDS: Chemical thermodynamics, Engine, Efficiency, Molecular machine.

  4. Thermodynamic chemical energy transfer mechanisms of non-equilibrium, quasi-equilibrium, and equilibrium chemical reactions

    International Nuclear Information System (INIS)

    Chemical energy transfer mechanisms at finite temperature are explored by a chemical energy transfer theory which is capable of investigating various chemical mechanisms of non-equilibrium, quasi-equilibrium, and equilibrium. Gibbs energy fluxes are obtained as a function of chemical potential, time, and displacement. Diffusion, convection, internal convection, and internal equilibrium chemical energy fluxes are demonstrated. The theory reveals that there are chemical energy flux gaps and broken discrete symmetries at the activation chemical potential, time, and displacement. The statistical, thermodynamic theory is the unification of diffusion and internal convection chemical reactions which reduces to the non-equilibrium generalization beyond the quasi-equilibrium theories of migration and diffusion processes. The relationship between kinetic theories of chemical and electrochemical reactions is also explored. The theory is applied to explore non-equilibrium chemical reactions as an illustration. Three variable separation constants indicate particle number constants and play key roles in describing the distinct chemical reaction mechanisms. The kinetics of chemical energy transfer accounts for the four control mechanisms of chemical reactions such as activation, concentration, transition, and film chemical reactions. - Highlights: • Chemical energy transfer theory is proposed for non-, quasi-, and equilibrium. • Gibbs energy fluxes are expressed by chemical potential, time, and displacement. • Relationship between chemical and electrochemical reactions is discussed. • Theory is applied to explore nonequilibrium energy transfer in chemical reactions. • Kinetics of non-equilibrium chemical reactions shows the four control mechanisms

  5. Are allometry and macroevolution related?

    Science.gov (United States)

    West, Bruce J.; West, Damien

    2011-05-01

    The allometric relationship between the basal metabolic rate B and total body mass M is B = aM, where the allometry coefficient a and the allometry exponent b have been fit to various data sets for over 150 years. The best fit of the allometry exponent to 391 mammalian species is given by Heusner [7] to be midway between the leading theoretical values of 2/3 and 3/4. Most theoretical investigations have focused on determining the proper value of b entailed by an appropriate biological model and with some notable exceptions ignored the allometry coefficient a altogether. Herein, we shift the focus and use the above data to settle on an empirical value of b that gives rise to an allometry coefficient with random variability described by a Pareto distribution. This new perspective suggests an interesting biological interpretation of the statistical fluctuations of the allometry coefficient. The time distribution of the intermittent fluctuations in a are determined to be of the same statistical form as those of speciation found in the punctuated equilibrium theory of macroevolution (Eldredge and Gould [3], Sneppen et al. [5] and Rikvold and Zia [17]).

  6. Equilibrium relationships for non-equilibrium chemical dependencies

    CERN Document Server

    Yablonsky, Gregory S; Marin, Guy B

    2010-01-01

    In contrast to common opinion, it is shown that equilibrium constants determine the time-dependent behavior of particular ratios of concentrations for any system of reversible first-order reactions. Indeed, some special ratios actually coincide with the equilibrium constant at any moment in time. This is established for batch reactors, and similar relations hold for steady-state plug-flow reactors, replacing astronomic time by residence time. Such relationships can be termed time invariants of chemical kinetics.

  7. Thermal Denaturation of Proteins and Chemical Equilibrium

    OpenAIRE

    Moroni, Laura; Gellini, Cristina; Remigio Salvi, Pier

    2015-01-01

    The thermal denaturation of proteins is considered as a process by means of which chemical equilibrium can be introduced to undergraduate students of Chemistry related curricula. In this approach chemical potential μ, Gibbs energy G, degree of advancement ξ and Le Châtelier principle are integrated with chemical equilibrium. With reference to α-Chymotrypsinogen A as a test case, the process is discussed in terms of a simplified two-state model. The activity is addressed to physical chemistry ...

  8. Chemical equilibrium modeling of detonation

    Energy Technology Data Exchange (ETDEWEB)

    Fried, Laurence E. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Bastea, Sorin [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2010-05-19

    Energetic materials are unique for having a strong exothermic reactivity, which has made them desirable for both military and commercial applications. Energetic materials are commonly divided into high explosives, propellants, and pyrotechnics. We will focus on high explosive (HE) materials here, although there is a great deal of commonality between the classes of energetic materials. Furthermore the history of HE materials is long, their condensed-phase chemical properties are poorly understood.

  9. Equilibrium and Sudden Events in Chemical Evolution

    CERN Document Server

    Weinberg, David H; Freudenburg, Jenna

    2016-01-01

    We present new analytic solutions for one-zone (fully mixed) chemical evolution models and explore their implications. In contrast to existing analytic models, we incorporate a realistic delay time distribution for Type Ia supernovae (SNIa) and can therefore track the separate evolution of $\\alpha$-elements produced by core collapse supernovae (CCSNe) and iron peak elements synthesized in both CCSNe and SNIa. In generic cases, $\\alpha$ and iron abundances evolve to an equilibrium at which element production is balanced by metal consumption and gas dilution, instead of continuing to increase over time. The equilibrium absolute abundances depend principally on supernova yields and the outflow mass loading parameter $\\eta$, while the equilibrium abundance ratio [$\\alpha$/Fe] depends mainly on yields and secondarily on star formation history. A stellar population can be metal-poor either because it has not yet evolved to equilibrium or because high outflow efficiency makes the equilibrium abundance itself low. Sy...

  10. Exploring Chemical Equilibrium in Hot Jovians

    Science.gov (United States)

    Blumenthal, Sarah; Harrington, Joseph; Mandell, Avi; Hébrard, Eric; Venot, Olivia; Cubillos, Patricio; Blecic, Jasmina; Challener, Ryan

    2016-01-01

    It has been established that equilibrium chemistry is usually achieved deep in the atmosphere of hot Jovians where timescales are short (Line and Yung 2013). Thus, equilibrium chemistry has been used as a starting point (setting initial conditions) for evaluating disequilibrium processes. We explore parameters of setting these initial conditions including departures from solar metallicity, the number of species allowed in a system, the types of species allowed in a system, and different thermodynamic libraries in an attempt to create a standard for evaluating equilibrium chemistry. NASA's open source code Chemical Equilibrium and Applications (CEA) is used to calculate model planet abundances by varying the metallicity, in the pressure regime 0.1 to 1 bar. These results are compared to a variety of exoplanets(Teq between 600 and 2100K) qualitatively by color maps of the dayside with different temperature redistributions. Additionally, CEA (with an up-dated thermodynamic library) is compared with the thermochemical model presented in Venotet al. (2012) for HD 209458b and HD 189733b. This same analysis is then applied to the cooler planet HD 97658b. Spectra are generated and we compare both models' outputs using the open source codetransit (https://github.com/exosports/transit) using the opacities of 15 molecules. We make the updated CEA thermodyanamic library and supporting Python scripts to do the CEA analyses available open source. Thiswork was supported by NASA Planetary Atmospheres grant NNX12AI69G.

  11. Chemical Equilibrium of Dust at Low Temperature

    Science.gov (United States)

    Ferguson, Jason W.; Alexander, David R.; Allard, France; Hauschildt, Peter H.

    The opacity of material is required whenever the detailed transfer of radiation through a gas is modeled. Computation of the opacity requires both a thorough knowledge of the chemical state of the gas (species populations) and the absorption/scattering behavior of those species. At low temperatures the equation of state (EOS) calculations become particularly complex. Our EOS computations assume chemical equilibrium and include over 600 solid and liquid species with data mainly from the JANAF database. We will present and discuss our EOS computations for gas temperatures from 2000 K to 300 K and a wide range of gas densities, pressures and chemical compositions. Large discontinuities in species abundances are seen when an individual grain species condenses. It has been known for some time that solid silicate and iron particles play important roles in the chemical equilibrium and opacity of a cool gas. Many other condensed species, including Al2 O3, CaTiO3, and even carbon at very low temperature, can play equally important roles.

  12. QUIL: a chemical equilibrium code. [HTGR

    Energy Technology Data Exchange (ETDEWEB)

    Lunsford, J.L.

    1977-02-01

    A chemical equilibrium code QUIL is described, along with two support codes FENG and SURF. QUIL is designed to allow calculations on a wide range of chemical environments, which may include surface phases. QUIL was written specifically to calculate distributions associated with complex equilibria involving fission products in the primary coolant loop of the high-temperature gas-cooled reactor. QUIL depends upon an energy-data library called ELIB. This library is maintained by FENG and SURF. FENG enters into the library all reactions having standard free energies of reaction that are independent of concentration. SURF enters all surface reactions into ELIB. All three codes are interactive codes written to be used from a remote terminal, with paging control provided. Plotted output is also available.

  13. Chemical equilibrium analysis of dry hydrogen combustion

    International Nuclear Information System (INIS)

    The present work is based on a thermo-chemical equilibrium model for studying the effect of combustion of hydrogen during postulated accident scenarios in nuclear reactor containments. This model is based on the method of element potentials which seeks to minimize the free energy of the system. The condition on internal energy balance is imposed as a constraint during the minimization process. Another simplified model purely based on the internal energy balance has also been implemented to investigate the isolated impact of free energy and the conditions under which it becomes dominant. The two models have been used to extract final pressures for a wide range of initial conditions and mixture compositions that are typically found during accident scenarios. In the absence of hydrogen combustion experimental data, such models will become important for laying down a first estimate on the possible outcomes. (author)

  14. Implementing an Equilibrium Law Teaching Sequence for Secondary School Students to Learn Chemical Equilibrium

    Science.gov (United States)

    Ghirardi, Marco; Marchetti, Fabio; Pettinari, Claudio; Regis, Alberto; Roletto, Ezio

    2015-01-01

    A didactic sequence is proposed for the teaching of chemical equilibrium law. In this approach, we have avoided the kinetic derivation and the thermodynamic justification of the equilibrium constant. The equilibrium constant expression is established empirically by a trial-and-error approach. Additionally, students learn to use the criterion of…

  15. Chemical Equilibrium as Balance of the Thermodynamic Forces

    CERN Document Server

    Zilbergleyt, B

    2004-01-01

    The article sets forth comprehensive basics of thermodynamics of chemical equilibrium as balance of the thermodynamic forces. Based on the linear equations of irreversible thermodynamics, De Donder definition of the thermodynamic force, and Le Chatelier's principle, new thermodynamics of chemical equilibrium offers an explicit account for multiple chemical interactions within the system. Basic relations between energetic characteristics of chemical transformations and reaction extents are based on the idea of chemical equilibrium as balance between internal and external thermodynamic forces, which is presented in the form of a logistic equation, containing only one new parameter. Solutions to the basic equation define the domain of states of the chemical system, from true equilibrium to true chaos. The new theory is derived exclusively from the currently recognized ideas and covers equilibrium thermodynamics as well as non-equilibrium thermodynamics in a unique concept.

  16. Analysis of the chemical equilibrium of combustion at constant volume

    OpenAIRE

    Marius BREBENEL

    2014-01-01

    Determining the composition of a mixture of combustion gases at a given temperature is based on chemical equilibrium, when the equilibrium constants are calculated on the assumption of constant pressure and temperature. In this paper, an analysis of changes occurring when combustion takes place at constant volume is presented, deriving a specific formula of the equilibrium constant. The simple reaction of carbon combustion in pure oxygen in both cases (constant pressure and constant ...

  17. Chemical equilibrium of glycerol carbonate synthesis from glycerol

    International Nuclear Information System (INIS)

    Research highlights: → Transesterification of glycerol with cyclic carbonates or alkyl carbonates is thermodynamically favourable for the preparation of glycerol carbonate from glycerol. → The reaction of glycerol and carbon dioxide is thermodynamically limited. → High temperature and low pressure is favourable to the reaction of glycerol and urea. → Increasing temperature can increase the chemical equilibrium constant for the reaction of glycerol and dimethyl carbonate. → For the reaction of glycerol and ethylene carbonate, increasing temperature can decrease the chemical equilibrium constant. - Abstract: In this paper, the chemical equilibrium for the glycerol carbonate preparation from glycerol was investigated. The chemical equilibrium constants were calculated for the reactions to produce glycerol carbonate from glycerol. The theoretical calculation was compared with the experimental results for the transesterification of glycerol with dimethyl carbonate. Transesterification of glycerol with cyclic carbonates or alkyl carbonates is thermodynamically favourable for producing glycerol carbonate from glycerol according to the equilibrium constant. Increasing temperature can increase the chemical equilibrium constant for the reaction of glycerol with dimethyl carbonate. For the reaction of glycerol with ethylene carbonate, increasing temperature can decrease the chemical equilibrium constant. The reaction of glycerol with carbon dioxide is thermodynamically limited. High temperature and low pressure are favourable to the reaction of glycerol and urea.

  18. Understanding Chemical Reaction Kinetics and Equilibrium with Interlocking Building Blocks

    Science.gov (United States)

    Cloonan, Carrie A.; Nichol, Carolyn A.; Hutchinson, John S.

    2011-01-01

    Chemical reaction kinetics and equilibrium are essential core concepts of chemistry but are challenging topics for many students, both at the high school and undergraduate university level. Visualization at the molecular level is valuable to aid understanding of reaction kinetics and equilibrium. This activity provides a discovery-based method to…

  19. Status of chemical equilibrium in relativistic heavy-ion collisions

    Indian Academy of Sciences (India)

    J Cleymans

    2003-04-01

    Recent work on chemical equilibrium in heavy-ion collisions is reviewed. The energy dependence of thermal parameters is discussed. The centrality dependence of thermal parameters at SPS energies is presented.

  20. Analysis of the chemical equilibrium of combustion at constant volume

    Directory of Open Access Journals (Sweden)

    Marius BREBENEL

    2014-04-01

    Full Text Available Determining the composition of a mixture of combustion gases at a given temperature is based on chemical equilibrium, when the equilibrium constants are calculated on the assumption of constant pressure and temperature. In this paper, an analysis of changes occurring when combustion takes place at constant volume is presented, deriving a specific formula of the equilibrium constant. The simple reaction of carbon combustion in pure oxygen in both cases (constant pressure and constant volume is next considered as example of application, observing the changes occurring in the composition of the combustion gases depending on temperature.

  1. Chemical heterogeneities in the mantle: The equilibrium thermodynamic approach

    Science.gov (United States)

    Tirone, M.; Buhre, S.; Schmück, H.; Faak, K.

    2016-02-01

    This study attempts to answer a simple and yet fundamental question in relation to our understanding of the chemical evolution of deep Earth and planetary interiors. Given two initially separate assemblages (lithologies) in chemical equilibrium can we predict the chemical and mineralogical compositions of the two assemblages when they are put together to form a new equilibrated system? Perhaps a common perception is that given sufficient time, the two assemblages will homogenize chemically and mineralogically, however from a chemical thermodynamic point of view, this is not the case. Certain petrological differences in terms of bulk composition, mineralogy and mineral abundance remain unless other processes, like melting or mechanical mixing come into play. While there is not a standard procedure to address this problem, in this study it is shown that by applying chemical thermodynamic principles and some reasonable assumptions, it is possible to determine the equilibrium composition of each of the two assemblages. Some examples that consider typical mantle rocks, peridotite, lherzolite, dunite and eclogite described by simplified chemical systems are used to illustrate the general approach. A preliminary application to evaluate the effect of melting a heterogeneous mantle in complete chemical equilibrium using a thermodynamic formulation coupled with a two-phase geodynamic model shows that major element composition of the melt product generated by different peridotites is very similar. This may explain the relative homogeneity of major elements of MORBs which could be the product of melting a relatively uniform mantle, as commonly accepted, or alternatively a peridotitic mantle with different compositions but in chemical equilibrium.

  2. Chemical Equilibrium and Polynomial Equations: Beware of Roots.

    Science.gov (United States)

    Smith, William R.; Missen, Ronald W.

    1989-01-01

    Describes two easily applied mathematical theorems, Budan's rule and Rolle's theorem, that in addition to Descartes's rule of signs and intermediate-value theorem, are useful in chemical equilibrium. Provides examples that illustrate the use of all four theorems. Discusses limitations of the polynomial equation representation of chemical…

  3. Concept Maps about Chemical Equilibrium and Students' Achievement Scores.

    Science.gov (United States)

    Wilson, Jan

    1996-01-01

    Examines relationships between structural characteristics of students' concept maps about chemical equilibrium and independent measures of their achievement in chemistry. Results indicate significant relationships between multidimensional scaling coordinates and test scores of recall of knowledge and its application and also reveal structural…

  4. Entropic origin of allometry relations

    Science.gov (United States)

    West, Bruce J.; West, Damien

    2015-03-01

    The theoretical allometry relation (AR) between the size of a network Y and a property of the network X is of the form X = aYb and has been known for nearly two centuries. The allometry coefficient a and allometry exponent b have been fit by various data sets over that time. The ubiquity of ARs in biology, sociology, ecology and indeed in virtually all the other science disciplines entreats science to find the origin of ARs. Data analysis indicates that the empirical AR is obtained with the replacements X → and Y → and the brackets denote an average over an ensemble of realizations of the network. It has been shown that the empirical AR cannot usually be derived from the theoretical one by simple averaging due to the fractal statistics of the fluctuations. Consequently we hypothesize that a possible origin of AR is the Principle of Minimum Entropy Generation (PMEG). We establish in support of this hypothesis that if the fluctuations in the allometry variables have fractal statistics then the PMEG entails the AR between a complex host network and a subnetwork strongly coupled to it.

  5. Boltzmann Equation Solver Adapted to Emergent Chemical Non-equilibrium

    CERN Document Server

    Birrell, Jeremiah

    2014-01-01

    We present a novel method to solve the spatially homogeneous and isotropic relativistic Boltzmann equation. We employ a basis set of orthogonal polynomials dynamically adapted to allow emergence of chemical non-equilibrium. Two time dependent parameters characterize the set of orthogonal polynomials, the effective temperature $T(t)$ and phase space occupation factor $\\Upsilon(t)$. In this first paper we address (effectively) massless fermions and derive dynamical equations for $T(t)$ and $\\Upsilon(t)$ such that the zeroth order term of the basis alone captures the number density and energy density of each particle distribution. We validate our method and illustrate the reduced computational cost and the ability to represent final state chemical non-equilibrium by studying a model problem that is motivated by the physics of the neutrino freeze-out processes in the early Universe, where the essential physical characteristics include reheating from another disappearing particle component ($e^\\pm$-annihilation).

  6. CHEMICAL EQUILIBRIUM OF SOIL SOLUTION IN STEPPE ZONE SOIL

    OpenAIRE

    A. A. Batukaev; A. P. Endovitsky; T. M. Minkina; V. P. Kalinichenko; Z. S. Dikaev; S. N. Sushkova

    2014-01-01

    Dynamics of material composition, migration and accumulation of salts is determined by chemical equilibrium in soil solution. Soil solution contains associated electrically neutral ion pairs CaCO30; CaSO40, MgCO30, MgSO40, charged ion pairs CaHCO3+, MgHCO3...

  7. Clouds in Super-Earth Atmospheres: Chemical Equilibrium Calculations

    OpenAIRE

    Mbarek, Rostom; Kempton, Eliza M. -R.

    2016-01-01

    Recent studies have unequivocally proven the existence of clouds in super-Earth atmospheres (Kreidberg et al. 2014). Here we provide a theoretical context for the formation of super-Earth clouds by determining which condensates are likely to form under the assumption of chemical equilibrium. We study super-Earth atmospheres of diverse bulk composition, which are assumed to form by outgassing from a solid core of chondritic material, following Schaefer & Fegley (2010). The super-Earth atmosphe...

  8. Effects of Confinement on Chemical Reaction Equilibrium in Nanoporous Materials

    Czech Academy of Sciences Publication Activity Database

    Smith, W.R.; Lísal, Martin; Brennan, J.K.

    2006-01-01

    Roč. 3984, - (2006), s. 743-751. ISSN 0302-9743 R&D Projects: GA ČR(CZ) GA203/05/0725; GA AV ČR 1ET400720507 Grant ostatní: NRCC(CA) OGP 1041 Institutional research plan: CEZ:AV0Z40720504 Keywords : nanoporous materials * chemical reaction equilibrium Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 0.402, year: 2005

  9. Non-equilibrium effects in high temperature chemical reactions

    Science.gov (United States)

    Johnson, Richard E.

    1987-01-01

    Reaction rate data were collected for chemical reactions occurring at high temperatures during reentry of space vehicles. The principle of detailed balancing is used in modeling kinetics of chemical reactions at high temperatures. Although this principle does not hold for certain transient or incubation times in the initial phase of the reaction, it does seem to be valid for the rates of internal energy transitions that occur within molecules and atoms. That is, for every rate of transition within the internal energy states of atoms or molecules, there is an inverse rate that is related through an equilibrium expression involving the energy difference of the transition.

  10. Geometric programming, chemical equilibrium, and the anti-entropy function.

    Science.gov (United States)

    Duffin, R J; Zener, C

    1969-07-01

    THE CULMINATION OF THIS PAPER IS THE FOLLOWING DUALITY PRINCIPLE OF THERMODYNAMICS: maximum S = minimum S(*). (1) The left side of relation (1) is the classical characterization of equilibrium. It says to maximize the entropy function S with respect to extensive variables which are subject to certain constraints. The right side of (1) is a new characterization of equilibrium and concerns minimization of an anti-entropy function S(*) with respect to intensive variables. Relation (1) is applied to the chemical equilibrium of a mixture of gases at constant temperature and volume. Then (1) specializes to minimum F = maximum F(*), (2) where F is the Helmholtz function for free energy and F(*) is an anti-Helmholtz function. The right-side of (2) is an unconstrained maximization problem and gives a simplified practical procedure for calculating equilibrium concentrations. We also give a direct proof of (2) by the duality theorem of geometric programming. The duality theorem of geometric programming states that minimum cost = maximum anti-cost. (30). PMID:16591769

  11. Exploring Chemical Equilibrium with Poker Chips: A General Chemistry Laboratory Exercise

    Science.gov (United States)

    Bindel, Thomas H.

    2012-01-01

    A hands-on laboratory exercise at the general chemistry level introduces students to chemical equilibrium through a simulation that uses poker chips and rate equations. More specifically, the exercise allows students to explore reaction tables, dynamic chemical equilibrium, equilibrium constant expressions, and the equilibrium constant based on…

  12. Early quark production and approach to chemical equilibrium

    Science.gov (United States)

    Gelfand, D.; Hebenstreit, F.; Berges, J.

    2016-04-01

    We perform real-time lattice simulations of out-of-equilibrium quark production in non-Abelian gauge theory in 3 +1 dimensions. Our simulations include the backreaction of quarks onto the dynamical gluon sector, which is particularly relevant for strongly correlated quarks. We observe fast isotropization and universal behavior of quarks and gluons at weak coupling and establish a quantitative connection to previous pure glue results. In order to understand the strongly correlated regime, we perform simulations for a large number of flavors and compare them to those obtained with two light quark flavors. By doing this we are able to provide estimates of the chemical equilibration time.

  13. Diffusion approximations to the chemical master equation only have a consistent stochastic thermodynamics at chemical equilibrium

    International Nuclear Information System (INIS)

    The stochastic thermodynamics of a dilute, well-stirred mixture of chemically reacting species is built on the stochastic trajectories of reaction events obtained from the chemical master equation. However, when the molecular populations are large, the discrete chemical master equation can be approximated with a continuous diffusion process, like the chemical Langevin equation or low noise approximation. In this paper, we investigate to what extent these diffusion approximations inherit the stochastic thermodynamics of the chemical master equation. We find that a stochastic-thermodynamic description is only valid at a detailed-balanced, equilibrium steady state. Away from equilibrium, where there is no consistent stochastic thermodynamics, we show that one can still use the diffusive solutions to approximate the underlying thermodynamics of the chemical master equation

  14. Network representations of knowledge about chemical equilibrium: Variations with achievement

    Science.gov (United States)

    Wilson, Janice M.

    This study examined variation in the organization of domain-specific knowledge by 50 Year-12 chemistry students and 4 chemistry teachers. The study used nonmetric multidimensional scaling (MDS) and the Pathfinder network-generating algorithm to investigate individual and group differences in student concepts maps about chemical equilibrium. MDS was used to represent the individual maps in two-dimensional space, based on the presence or absence of paired propositional links. The resulting separation between maps reflected degree of hierarchical structure, but also reflected independent measures of student achievement. Pathfinder was then used to produce semantic networks from pooled data from high and low achievement groups using proximity matrices derived from the frequencies of paired concepts. The network constructed from maps of higher achievers (coherence measure = 0.18, linked pairs = 294, and number of subjects = 32) showed greater coherence, more concordance in specific paired links, more important specific conceptual relationships, and greater hierarchical organization than did the network constructed from maps of lower achievers (coherence measure = 0.12, linked pairs = 552, and number of subjects = 22). These differences are interpreted in terms of qualitative variation in knowledge organization by two groups of individuals with different levels of relative expertise (as reflected in achievement scores) concerning the topic of chemical equilibrium. The results suggest that the technique of transforming paired links in concept maps into proximity matrices for input to multivariate analyses provides a suitable methodology for comparing and documenting changes in the organization and structure of conceptual knowledge within and between individual students.

  15. Chemical non-equilibrium flow analysis of H2 fueled scramjet nozzle

    OpenAIRE

    Yue Huang; Peiyong Wang; Yang Dou; Fei Xing

    2015-01-01

    A numerical analysis of the chemical non-equilibrium phenomena in a scramjet nozzle has been performed using CHEMKIN software. Different operating conditions of the Hyshot scramjet nozzle were simulated and analyzed. Three chemical status, frozen flow, equilibrium flow, and non-equilibrium flow, were tested and compared to demonstrate the chemical reaction effect on nozzle flow field. The real non-equilibrium flow simulation result is between those of the two limiting cases: frozen flow and e...

  16. Minimizing the Free Energy: A Computer Method for Teaching Chemical Equilibrium Concepts.

    Science.gov (United States)

    Heald, Emerson F.

    1978-01-01

    Presents a computer method for teaching chemical equilibrium concepts using material balance conditions and the minimization of the free energy. Method for the calculation of chemical equilibrium, the computer program used to solve equilibrium problems and applications of the method are also included. (HM)

  17. QUIC: a chemical kinetics code for use with the chemical equilibrium code QUIL

    International Nuclear Information System (INIS)

    A chemical rate kinetics code QUIC is described, along with a support code RATE. QUIC is designed to allow chemical kinetics calculations on a wide variety of chemical environments while operating in the overlay environment of the chemical equilibrium code QUIL. QUIC depends upon a rate-data library called LIBR. This library is maintained by RATE. RATE enters into the library all reactions in a standardized format. The code QUIC, operating in conjunction with QUIL, is interactive and written to be used from a remote terminal, with paging control provided. Plotted output is also available

  18. From Chemical Forces to Chemical Rates: A Historical/Philosophical Foundation for the Teaching of Chemical Equilibrium

    Science.gov (United States)

    Quílez, Juan

    2009-09-01

    With this paper, our main aim is to contribute to the realisation of the chemical reactivity concept, tracing the historical evolution of the concept of chemical affinity that eventually supported the concept of chemical equilibrium. We will concentrate on searching for the theoretical grounds of three key chemical equilibrium ideas: ‚incomplete reaction’, ‚reversibility’ and ‚dynamics’. In addition, the paper aims to promote teachers’ philosophical/historical chemical knowledge. The starting point of this historical reconstruction will be the state of the art in the construction of the first affinity tables, based on the concept of elective affinities, during the 18th century. Berthollet reworked this idea, considering that the amount of the substances involved in a reaction was a key factor accounting for the chemical forces. Guldberg and Waage attempted to measure those forces, formulating the first affinity mathematical equations. Afterwards, the first ideas providing a molecular interpretation of the macroscopic properties of equilibrium reactions are presented. Eventually, theoretical chemists integrated previous findings into a new field: thermodynamics. This historical approach may serve as a base for an appropriate sequencing of the teaching and learning of chemical equilibrium. Hence, this paper tries to go beyond the simple development of teachers’ conceptions of the nature of chemistry, for it gives suggestions about how teachers may translate such understandings into classroom practice.

  19. Clouds Composition in Super-Earth Atmospheres: Chemical Equilibrium Calculations

    Science.gov (United States)

    Kempton, Eliza M.-R.; Mbarek, Rostom

    2015-12-01

    Attempts to determine the composition of super-Earth atmospheres have so far been plagued by the presence of clouds. Yet the theoretical framework to understand these clouds is still in its infancy. For the super-Earth archetype GJ 1214b, KCl, Na2S, and ZnS have been proposed as condensates that would form under the condition of chemical equilibrium, if the planet’s atmosphere has a bulk composition near solar. Condensation chemistry calculations have not been presented for a wider range of atmospheric bulk composition that is to be expected for super-Earth exoplanets. Here we provide a theoretical context for the formation of super-Earth clouds in atmospheres of varied composition by determining which condensates are likely to form, under the assumption of chemical equilibrium. We model super-Earth atmospheres assuming they are formed by degassing of volatiles from a solid planetary core of chondritic material. Given the atomic makeup of these atmospheres, we minimize the global Gibbs free energy of over 550 gases and condensates to obtain the molecular composition of the atmospheres over a temperature range of 350-3,000 K. Clouds should form along the temperature-pressure boundaries where the condensed species appear in our calculations. The super-Earth atmospheres that we study range from highly reducing to oxidizing and have carbon to oxygen (C:O) ratios that are both sub-solar and super-solar, thereby spanning a diverse range of atmospheric composition that is appropriate for low-mass exoplanets. Some condensates appear across all of our models. However, the majority of condensed species appear only over specific ranges of H:O and C:O ratios. We find that for GJ 1214b, KCl is the primary cloud-forming condensate at solar composition, in agreement with previous work. However, for oxidizing atmospheres, where H:O is less than unity, K2SO4 clouds form instead. For carbon-rich atmospheres with super-solar C:O ratios, graphite clouds additionally appear. At

  20. Clouds in Super-Earth Atmospheres: Chemical Equilibrium Calculations

    CERN Document Server

    Mbarek, Rostom

    2016-01-01

    Recent studies have unequivocally proven the existence of clouds in super-Earth atmospheres (Kreidberg et al. 2014). Here we provide a theoretical context for the formation of super-Earth clouds by determining which condensates are likely to form under the assumption of chemical equilibrium. We study super-Earth atmospheres of diverse bulk composition, which are assumed to form by outgassing from a solid core of chondritic material, following Schaefer & Fegley (2010). The super-Earth atmospheres that we study arise from planetary cores made up of individual types of chondritic meteorites. They range from highly reducing to oxidizing and have carbon to oxygen (C:O) ratios that are both subsolar and super-solar, thereby spanning a range of atmospheric composition that is appropriate for low-mass exoplanets. Given the atomic makeup of these atmospheres, we minimize the global Gibbs free energy of formation for over 550 gases and condensates to obtain the molecular composition of the atmospheres over a temper...

  1. BOREAS TE-6 Allometry Data

    Science.gov (United States)

    Hall, Forrest G. (Editor); Papagno, Andrea (Editor); Gower, Stith T.; Vogel, Jason G.

    2000-01-01

    The BOREAS TE-6 team collected several data sets in support of its efforts to characterize and interpret information on the plant biomass, allometry, biometry, sapwood, leaf area index, net primary production, soil temperature, leaf water potential, soil CO2 flux, and multivegetation imagery of boreal vegetation. This data set includes tree measurements conducted on the above-ground biomass of trees in the BOREAS NSA and SSA during the growing seasons of 1994 and 1995 and the derived allometric relationships/equations. The data are stored in ASCII files. The data files are available on a CD-ROM (see document number 20010000884), or from the Oak Ridge National Laboratory (ORNL) Distrobuted Activity Archive Center (DAAC).

  2. CHEMICAL EQUILIBRIUM OF SOIL SOLUTION IN STEPPE ZONE SOIL

    Directory of Open Access Journals (Sweden)

    A. A. Batukaev

    2014-01-01

    Full Text Available Dynamics of material composition, migration and accumulation of salts is determined by chemical equilibrium in soil solution. Soil solution contains associated electrically neutral ion pairs CaCO30; CaSO40, MgCO30, MgSO40, charged ion pairs CaHCO3+, MgHCO3+, NaCO3-, NaSO4-, CaOH+, MgOH+. Calculation method is proposed for quantitative assessment of real ion forms in the soil solution of chestnut solonetz soil complex. Were proposed equations to calculate free and associated forms of ions. To solve the equations were used an iteration, a linear interpolation of equilibrium constants, a Method of Ionic Pairs including a law of initial concentration preservation, a law of the operating masses of equilibrium system, the concentration constants of ion pair dissociation on the law of operating masses. Was determined the quantity of ion free form and a coefficient of ion association as ratio of ions free form to analytical content ?e = Cass/Can. The association of ions varies in individual soils and soil layer. Increasing soil solution salinity amplifies the ions association. In form of ionic pairs in soil solution are: 11.8-53.8% of Ca2+; 9.4-57.3% of Mg2+; 0.7-11.9% of Na+; 2.2-22.3% of HCO3-, 11.8-62.7% of SO42-. The ion CO32- is high associated, the share of ions in associated form is up to 92.7%. The degree of soil solution saturation was obtained for three level of approximation accounting on analytical concentration, calculated association coefficient, calculated coefficient of association. Relating to thermodynamic solubility product S0, the mathematical product of analytical ionic pairs

  3. The Adverse Effects of Le Chatelier's Principle on Teacher Understanding of Chemical Equilibrium

    Science.gov (United States)

    Cheung, Derek

    2009-01-01

    Although the scientific inadequacy of Le Chatelier's principle has long been documented in the literature, the principle is still treated as a central concept of chemical equilibrium by textbook writers and teachers in many countries. In the past, researchers' interest has focused on student misconceptions about chemical equilibrium and has…

  4. Geochemical modelling of groundwater evolution using chemical equilibrium codes

    International Nuclear Information System (INIS)

    Geochemical equilibrium codes are a modern tool in studying interaction between groundwater and solid phases. The most common used programs and application subjects are shortly presented in this article. The main emphasis is laid on the approach method of using calculated results in evaluating groundwater evolution in hydrogeological system. At present in geochemical equilibrium modelling also kinetic as well as hydrologic constrains along a flow path are taken into consideration

  5. Determination of solute organic concentration in contaminated soils using a chemical-equilibrium soil column system

    DEFF Research Database (Denmark)

    Gamst, Jesper; Kjeldsen, Peter; Christensen, Thomas Højlund

    determination of solute concentration in a contaminated soil were developed; (1) a chemical Equilibrium and Recirculation column test for Volatile organic chemicals (ER-V) and (2) a chemical Equilibrium and Recirculation column test for Hydrophobic organic chemicals (ER-H). The two test systems were evaluated...... 80) an unacceptable recovery was found (9%). The contact time needed for obtaining chemical equilibrium was tested in the ER-H system by performing five test with different duration (1, 2, 4, 7 and 19 days) using the low organic carbon soil. Seven days of contact time appeared sufficient for......Groundwater risk assessment of contaminated soils implies determination of the solute concentration leaching out of the soil. Determination based on estimation techniques or simple experimental batch approach has proven inadequate. Two chemical equilibrium soil column leaching tests for...

  6. The allometry of prey preferences.

    Directory of Open Access Journals (Sweden)

    Gregor Kalinkat

    Full Text Available The distribution of weak and strong non-linear feeding interactions (i.e., functional responses across the links of complex food webs is critically important for their stability. While empirical advances have unravelled constraints on single-prey functional responses, their validity in the context of complex food webs where most predators have multiple prey remain uncertain. In this study, we present conceptual evidence for the invalidity of strictly density-dependent consumption as the null model in multi-prey experiments. Instead, we employ two-prey functional responses parameterised with allometric scaling relationships of the functional response parameters that were derived from a previous single-prey functional response study as novel null models. Our experiments included predators of different sizes from two taxonomical groups (wolf spiders and ground beetles simultaneously preying on one small and one large prey species. We define compliance with the null model predictions (based on two independent single-prey functional responses as passive preferences or passive switching, and deviations from the null model as active preferences or active switching. Our results indicate active and passive preferences for the larger prey by predators that are at least twice the size of the larger prey. Moreover, our approach revealed that active preferences increased significantly with the predator-prey body-mass ratio. Together with prior allometric scaling relationships of functional response parameters, this preference allometry may allow estimating the distribution of functional response parameters across the myriads of interactions in natural ecosystems.

  7. Dynamic processes of conceptual change: Analysis of constructing mental models of chemical equilibrium

    Science.gov (United States)

    Chiu, Mei-Hung; Chou, Chin-Cheng; Liu, Chia-Ju

    2002-10-01

    The purpose of this study was to investigate students' mental models of chemical equilibrium using dynamic science assessments. Research in chemical education has shown that students at various levels have misconceptions about chemical equilibrium. According to Chi's theory of conceptual change, the concept of chemical equilibrium has constraint-based features (e.g., random, simultaneous, uniform activities) that might prevent students from deeply understanding the nature of the concept of chemical equilibrium. In this study, we examined how students learned and constructed their mental models of chemical equilibrium in a cognitive apprenticeship context. Thirty 10th-grade students participated in the study: 10 in a control group and 20 in a treatment group. Both groups were presented with a series of hands-on chemical experiments. The students in the treatment group were instructed based on the main features of cognitive apprenticeship (CA), such as coaching, modeling, scaffolding, articulation, reflection, and exploration. However, the students in the control group (non-CA group) learned from the tutor without explicit CA support. The results revealed that the CA group significantly outperformed the non-CA group. The students in the CA group were capable of constructing the mental models of chemical equilibrium - including dynamic, random activities of molecules and interactions between molecules in the microworld - whereas the students in the non-CA group failed to construct similar correct mental models of chemical equilibrium. The study focuses on the process of constructing mental models, on dynamic changes, and on the actions of students (such as self-monitoring/self-correction) who are learning the concept of chemical equilibrium. Also, we discuss the implications for science education.

  8. Chemical Equilibrium in Supramolecular Systems as Studied by NMR Spectrometry

    Science.gov (United States)

    Gonzalez-Gaitano, Gustavo; Tardajos, Gloria

    2004-01-01

    Undergraduate students are required to study the chemical balance in supramolecular assemblies constituting two or more interacting species, by using proton NMR spectrometry. A good knowledge of physical chemistry, fundamentals of chemical balance, and NMR are pre-requisites for conducting this study.

  9. Allometry in damselfly ornamental and genital traits: solving some pitfalls of allometry and sexual selection.

    Science.gov (United States)

    Córdoba-Aguilar, A; López-Valenzuela, A; Brunel, O

    2010-12-01

    Static allometry of sexually selected traits has been the subject of intense research recently. However, some pitfalls for this kind of research are: (a) the functions of sexual traits are largely unknown; (b) more than one body size indicator must be measured; and, (c) allometry must be examined under different environmental circumstances to see whether allometric values change. Using Hetaerina americana damselflies, we investigated the type of allometry exhibited by a wing red spot and aedeagal width. These traits are positively selected during pre-copulatory male-male contests and post-copulatory female stimulation, respectively. As body size indicators, we used wing length and head width. It has been documented that expression of both sexual traits varies throughout the year. Thus, allometry was examined in different times of the year. We also investigated the allometry of aedeagal width and vaginal width at the zone where female stimulation takes place. We found no clear pattern of any allometric relationship for male and female traits and for both body size indicators at all times sampled. Our results contrast with patterns of negative allometry exhibited by genital traits in other animals. PMID:20938802

  10. Efficient chemical equilibrium calculations for geochemical speciation and reactive transport modelling

    Science.gov (United States)

    Leal, Allan M. M.; Blunt, Martin J.; LaForce, Tara C.

    2014-04-01

    Chemical equilibrium calculations are essential for many environmental problems. It is also a fundamental tool for chemical kinetics and reactive transport modelling, since these applications may require hundreds to billions equilibrium calculations in a single simulation. Therefore, an equilibrium method for such critical applications must be very efficient, robust and accurate. In this work we demonstrate the potential effectiveness of a novel Gibbs energy minimisation algorithm for reactive transport simulations. The algorithm includes strategies to converge from poor initial guesses; capabilities to specify non-linear equilibrium constraints such as pH of an aqueous solution and activity or fugacity of a species; a rigorous phase stability test to determine the unstable phases; and a strategy to boost the convergence speed of the calculations to quadratic rates, requiring only few iterations to converge. We use this equilibrium method to solve geochemical problems relevant to carbon storage in saline aquifers, where aqueous, gaseous and minerals phases are present. The problems are formulated to mimic the ones found in kinetics and transport simulations, where a sequence of equilibrium calculations are performed, each one using the previous solution as the initial guess. The efficiency and convergence rates of the calculations are presented, which require an average of 1-2 iterations. These results indicate that critical applications such as chemical kinetics and reactive transport modelling can potentially benefit by using this multiphase equilibrium algorithm.

  11. Development and Assessment of a Paper Electrophoresis Simulation Software for Chemical Equilibrium Teaching and Learning

    Directory of Open Access Journals (Sweden)

    E. Montagna

    2014-08-01

    Full Text Available Chemical Equilibrium misconceptions impaired the learning of many biochemicalundergraduate content. It was widely reinforced by chemical education data. On the otherhand there was no data for the consequences in biochemistry learning. OBJECTIVE Weproposed the construction of an Aminoacid Paper Electrophoresis software as a tool forChemical Equilibrium teaching and learning which aims to integrate the representationallevels, being macroscopic, microscopic and symbolic in a way to evidence to student thedynamic character of the equilibrium phenomena. It attenuates misconceptions andreduces impairments on biochemistry learning. Although the simulator is based onclassical biochemistry topic it is designed to deal with chemical equilibrium concepts in thecontext of biochemistry. MATERIALS AND METHODS: The software is an PaperElectrophoresis Simulator programmed in HTML5 language. It guides the student stepstoward the simulation showing the technique fundamentals and variables allowing tochoose aminoacids in a list, as well as build even tetrapeptides and run even four samplesin a single simulation after what is defined a pH for simulation. The simulation results areshown in a depiction of a paper electrophoresis device (macroscopic the speciesproportion in the medium based on the Handerson-Hasselbalch formula (symbolic and thespecies charge change based on the medium pH (microscopic. All activities are guided bya task list based on previous diagnostic on chemical equilibrium misconceptions.RESULTS AND DISCUSSION: Results were based on observation of students classdiscussion and survey. Many of previously diagnosed misconceptions were attenuated intests of chemical equilibrium falling from a 72% to 35% error average; and a studentssurvey agreed with simulator objectives (90%, ease of use (94%, chemicalrepresentations straightness (82%, simulation results (71% integration ofrepresentational levels (87%. CONCLUSIONS: Students declared the software

  12. A Unified Graphical Representation of Chemical Thermodynamics and Equilibrium

    Science.gov (United States)

    Hanson, Robert M.

    2012-01-01

    During the years 1873-1879, J. Willard Gibbs published his now-famous set of articles that form the basis of the current perspective on chemical thermodynamics. The second article of this series, "A Method of Geometrical Representation of the Thermodynamic Properties of Substances by Means of Surfaces," published in 1873, is particularly notable…

  13. Computing multi-species chemical equilibrium with an algorithm based on the reaction extents

    DEFF Research Database (Denmark)

    Paz-Garcia, Juan Manuel; Johannesson, Björn; Ottosen, Lisbeth M.;

    2013-01-01

    A mathematical model for the solution of a set of chemical equilibrium equations in a multi-species and multiphase chemical system is described. The computer-aid solution of model is achieved by means of a Newton-Raphson method enhanced with a line-search scheme, which deals with the non-negative...

  14. Direct Monte Carlo simulation of the chemical equilibrium composition of detonation products

    Energy Technology Data Exchange (ETDEWEB)

    Shaw, M.S.

    1993-06-01

    A new Monte Carlo simulation method has been developed by the author which gives the equilibrium chemical composition of a molecular fluid directly. The usual NPT ensemble (isothermal-isobaric) is implemented with N being the number of atoms instead of molecules. Changes in chemical composition are treated as correlated spatial moves of atoms. Given the interaction potentials between molecular products, ``exact`` EOS points including the equilibrium chemical composition can be determined from the simulations. This method is applied to detonation products at conditions in the region near the Chapman- Jouget state. For the example of NO, it is shown that the CJ detonation velocity can be determined to a few meters per second. A rather small change in cross potentials is shown to shift the chemical equilibrium and the CJ conditions significantly.

  15. Chemical evolution of the Earth: Equilibrium or disequilibrium process?

    Science.gov (United States)

    Sato, M.

    1985-01-01

    To explain the apparent chemical incompatibility of the Earth's core and mantle or the disequilibrium process, various core forming mechanisms have been proposed, i.e., rapid disequilibrium sinking of molten iron, an oxidized core or protocore materials, and meteorite contamination of the upper mantle after separation from the core. Adopting concepts used in steady state thermodynamics, a method is devised for evaluating how elements should distribute stable in the Earth's interior for the present gradients of temperature, pressure, and gravitational acceleration. Thermochemical modeling gives useful insights into the nature of chemical evolution of the Earth without overly speculative assumptions. Further work must be done to reconcile siderophile elements, rare gases, and possible light elements in the outer core.

  16. Vapor–Liquid Equilibrium Coupled with Chemical Reaction (Transesterification)

    Czech Academy of Sciences Publication Activity Database

    Wichterle, Ivan; Aim, Karel

    - : -, 2005 - (Domanska-Zelazna, U.; Malanowski, S.), s.68-69 ISBN 83-920719-1-3. [European Symposium on Applied Thermodynamics ESAT 2005 /21./. Jurata (PL), 01.06.2005-05.06.2005] R&D Projects: GA ČR(CZ) GA203/03/1588 Institutional research plan: CEZ:AV0Z40720504 Keywords : phase equilibria * chemical equilibria * transesterification Subject RIV: CF - Physical ; Theoretical Chemistry

  17. Calculation of complex chemical equilibrium compositions of composite rocket propellants combustion products

    Directory of Open Access Journals (Sweden)

    NIKOLA KILIBARDA

    2000-11-01

    Full Text Available An adequate method for calculating chemical equilibrium in a predominantly gaseous, multi-component reactive mixture was investigated and successfully applied. This method involves the stated equilibrium reaction scheme, including, first, the formation of chemical species, of which concentrations prevail in the mixture, then the formation of gaseous atomic species by dissociation of previous ones, and, finally, the formation of complex chemical species from the atomic species. A computer program, which permits calculations of equilibrium compositions by the iteration procedure, has been developed. The results of calculations have been compared with data obtained by the programs OPHELIE, MICROPEP, and the program SPP, as documented in the NASA-Lewis Code, which is presently the world-wide standard. All comparisons gave satisfactory agreement.

  18. An Artificial Neural Network Approach to the Solution of Molecular Chemical Equilibrium

    CERN Document Server

    Ramos, A A

    2005-01-01

    A novel approach is presented for the solution of instantaneous chemical equilibrium problems. The chemical equilibrium can be considered, due to its intrinsically local character, as a mapping of the three-dimensional parameter space spanned by the temperature, hydrogen density and electron density into many one-dimensional spaces representing the number density of each species. We take advantage of the ability of artificial neural networks to approximate non-linear functions and construct neural networks for the fast and efficient solution of the chemical equilibrium problem in typical stellar atmosphere physical conditions. The neural network approach has the advantage of providing an analytic function, which can be rapidly evaluated. The networks are trained with a learning set (that covers the entire parameter space) until a relative error below 1% is reached. It has been verified that the networks are not overtrained by using an additional verification set. The networks are then applied to a snapshot of...

  19. Modelling Chemical Equilibrium Partitioning with the GEMS-PSI Code

    Energy Technology Data Exchange (ETDEWEB)

    Kulik, D.; Berner, U.; Curti, E

    2004-03-01

    Sorption, co-precipitation and re-crystallisation are important retention processes for dissolved contaminants (radionuclides) migrating through the sub-surface. The retention of elements is usually measured by empirical partition coefficients (Kd), which vary in response to many factors: temperature, solid/liquid ratio, total contaminant loading, water composition, host-mineral composition, etc. The Kd values can be predicted for in-situ conditions from thermodynamic modelling of solid solution, aqueous solution or sorption equilibria, provided that stoichiometry, thermodynamic stability and mixing properties of the pure components are known (Example 1). Unknown thermodynamic properties can be retrieved from experimental Kd values using inverse modelling techniques (Example 2). An efficient, advanced tool for performing both tasks is the Gibbs Energy Minimization (GEM) approach, implemented in the user-friendly GEM-Selector (GEMS) program package, which includes the Nagra-PSI chemical thermodynamic database. The package is being further developed at PSI and used extensively in studies relating to nuclear waste disposal. (author)

  20. Modelling Chemical Equilibrium Partitioning with the GEMS-PSI Code

    International Nuclear Information System (INIS)

    Sorption, co-precipitation and re-crystallisation are important retention processes for dissolved contaminants (radionuclides) migrating through the sub-surface. The retention of elements is usually measured by empirical partition coefficients (Kd), which vary in response to many factors: temperature, solid/liquid ratio, total contaminant loading, water composition, host-mineral composition, etc. The Kd values can be predicted for in-situ conditions from thermodynamic modelling of solid solution, aqueous solution or sorption equilibria, provided that stoichiometry, thermodynamic stability and mixing properties of the pure components are known (Example 1). Unknown thermodynamic properties can be retrieved from experimental Kd values using inverse modelling techniques (Example 2). An efficient, advanced tool for performing both tasks is the Gibbs Energy Minimization (GEM) approach, implemented in the user-friendly GEM-Selector (GEMS) program package, which includes the Nagra-PSI chemical thermodynamic database. The package is being further developed at PSI and used extensively in studies relating to nuclear waste disposal. (author)

  1. The efficiency of driving chemical reactions by a physical non-equilibrium is kinetically controlled.

    Science.gov (United States)

    Göppel, Tobias; Palyulin, Vladimir V; Gerland, Ulrich

    2016-07-27

    An out-of-equilibrium physical environment can drive chemical reactions into thermodynamically unfavorable regimes. Under prebiotic conditions such a coupling between physical and chemical non-equilibria may have enabled the spontaneous emergence of primitive evolutionary processes. Here, we study the coupling efficiency within a theoretical model that is inspired by recent laboratory experiments, but focuses on generic effects arising whenever reactant and product molecules have different transport coefficients in a flow-through system. In our model, the physical non-equilibrium is represented by a drift-diffusion process, which is a valid coarse-grained description for the interplay between thermophoresis and convection, as well as for many other molecular transport processes. As a simple chemical reaction, we consider a reversible dimerization process, which is coupled to the transport process by different drift velocities for monomers and dimers. Within this minimal model, the coupling efficiency between the non-equilibrium transport process and the chemical reaction can be analyzed in all parameter regimes. The analysis shows that the efficiency depends strongly on the Damköhler number, a parameter that measures the relative timescales associated with the transport and reaction kinetics. Our model and results will be useful for a better understanding of the conditions for which non-equilibrium environments can provide a significant driving force for chemical reactions in a prebiotic setting. PMID:27147197

  2. Chemical non-equilibrium flow analysis of H2 fueled scramjet nozzle

    Directory of Open Access Journals (Sweden)

    Yue Huang

    2015-03-01

    Full Text Available A numerical analysis of the chemical non-equilibrium phenomena in a scramjet nozzle has been performed using CHEMKIN software. Different operating conditions of the Hyshot scramjet nozzle were simulated and analyzed. Three chemical status, frozen flow, equilibrium flow, and non-equilibrium flow, were tested and compared to demonstrate the chemical reaction effect on nozzle flow field. The real non-equilibrium flow simulation result is between those of the two limiting cases: frozen flow and equilibrium flow, and is closer to that of frozen flow. With complete combustion condition at nozzle inlet, the radical recombination reaction releases tremendous amount of heat and this heat is mainly used to increases gas temperature and has only slight increasing effect on thrust. With incomplete combustion condition at nozzle inlet, both combustion reaction and radical recombination occur in the nozzle, the effect of reaction heat release on thrust depends on the degree of combustion completeness at nozzle inlet, it could increase thrust tremendously compared to frozen flow.

  3. Fluctuations as a test of chemical non-equilibrium at the LHC

    CERN Document Server

    Begun, Viktor

    2016-01-01

    It is shown that large chemical potential leads to the significant increase of multiplicity fluctuations for bosons, and makes the fluctuations infinite in the case of Bose-Einstein condensation. It allows to distinguish between the models that explain the anomalous proton to pion ratio and the low transverse momentum enhancement of pion spectra in Pb+Pb collisions at the LHC within chemical equilibrium or non-equilibrium models. The effects of resonance decays, finite size of the system, requirements to the event statistics, different momentum cuts, and limited detector acceptance are considered. The obtained results show the possibility to observe a substantial increase of the normalized kurtosis for positively or negatively charged pions in the case of non-equilibrium or partial pion condensation using currently measured data.

  4. Exploring the Impact of Argumentation on Pre-Service Science Teachers' Conceptual Understanding of Chemical Equilibrium

    Science.gov (United States)

    Aydeniz, Mehmet; Dogan, Alev

    2016-01-01

    This study examines the impact of argumentation on pre-service science teachers' (PST) conceptual understanding of chemical equilibrium. The sample consisted of 57 first-year PSTs enrolled in a teacher education program in Turkey. Thirty two of the 57 PSTs who participated in this study were in the experimental group and 25 in the control group.…

  5. A Teaching Sequence for Learning the Concept of Chemical Equilibrium in Secondary School Education

    Science.gov (United States)

    Ghirardi, Marco; Marchetti, Fabio; Pettinari, Claudio; Regis, Alberto; Roletto, Ezio

    2014-01-01

    A novel didactic sequence is proposed for the teaching of chemical equilibrium. This teaching sequence takes into account the historical and epistemological evolution of the concept, the alternative conceptions and learning difficulties highlighted by teaching science and research in education, and the need to focus on both the students'…

  6. Numerical kinetic model including equilibrium and rate equations for chemical reactions of actinide elements

    International Nuclear Information System (INIS)

    Numerical simulation method was examined for chemical reactions of actinide elements U, Pu, Np, and Tc etc. in an aqueous nitric acid solution. It is known that the numerical calculation for the Purex process with chemical reactions and liquid flow becomes stiff, because time constant for the chemical reactions is two to three order of magnitude smaller due to the very fast reactions than that of mass transfer or of reaching distribution equilibrium. Recently in order to increase a time step Δt the partial equilibrium (P.E.) model, in which some very fast reactions are treated by the equilibrium law whereas other reactions are by the rate law, has been proposed. In the present study concentration change of the solutes in an aqueous solution with 30 chemical reactions, of which 4 are expressed by equilibrium equations, has been calculated. Description of the P.E. model and the comparison of the results and cpu time between the kinetic and the P.E. models are given. (author)

  7. A Simple Method to Calculate the Temperature Dependence of the Gibbs Energy and Chemical Equilibrium Constants

    Science.gov (United States)

    Vargas, Francisco M.

    2014-01-01

    The temperature dependence of the Gibbs energy and important quantities such as Henry's law constants, activity coefficients, and chemical equilibrium constants is usually calculated by using the Gibbs-Helmholtz equation. Although, this is a well-known approach and traditionally covered as part of any physical chemistry course, the required…

  8. A study of adsorption equilibrium on quaternary ammonium resin in uranyl sulphate solution by chemical equivalent method

    International Nuclear Information System (INIS)

    The exchange equilibrium between SO42- and HSO4- on quaternary ammonium strong base resin and the effect of ClO4- on the equilibrium are studied by chemical equivalent method. On the basis of the results the adsorption equilibrium of the resin in uranyl sulphate solution which is similar to the solution in uranium hydrometallurgy process is also studied

  9. Computer program for calculation of complex chemical equilibrium compositions and applications. Part 1: Analysis

    Science.gov (United States)

    Gordon, Sanford; Mcbride, Bonnie J.

    1994-01-01

    This report presents the latest in a number of versions of chemical equilibrium and applications programs developed at the NASA Lewis Research Center over more than 40 years. These programs have changed over the years to include additional features and improved calculation techniques and to take advantage of constantly improving computer capabilities. The minimization-of-free-energy approach to chemical equilibrium calculations has been used in all versions of the program since 1967. The two principal purposes of this report are presented in two parts. The first purpose, which is accomplished here in part 1, is to present in detail a number of topics of general interest in complex equilibrium calculations. These topics include mathematical analyses and techniques for obtaining chemical equilibrium; formulas for obtaining thermodynamic and transport mixture properties and thermodynamic derivatives; criteria for inclusion of condensed phases; calculations at a triple point; inclusion of ionized species; and various applications, such as constant-pressure or constant-volume combustion, rocket performance based on either a finite- or infinite-chamber-area model, shock wave calculations, and Chapman-Jouguet detonations. The second purpose of this report, to facilitate the use of the computer code, is accomplished in part 2, entitled 'Users Manual and Program Description'. Various aspects of the computer code are discussed, and a number of examples are given to illustrate its versatility.

  10. Three model space experiments on chemical reactions. [Gibbs adsorption, equilibrium shift and electrodeposition

    Science.gov (United States)

    Grodzka, P.; Facemire, B.

    1977-01-01

    Three investigations conducted aboard Skylab IV and Apollo-Soyuz involved phenomena that are of interest to the biochemistry community. The formaldehyde clock reaction and the equilibrium shift reaction experiments conducted aboard Apollo Soyuz demonstrate the effect of low-g foams or air/liquid dispersions on reaction rate and chemical equilibrium. The electrodeposition reaction experiment conducted aboard Skylab IV demonstrate the effect of a low-g environment on an electrochemical displacement reaction. The implications of the three space experiments for various applications are considered.

  11. Chemical equilibrium constants of rare earth nitrates and tri-n-butyl phosphate complex formation

    Institute of Scientific and Technical Information of China (English)

    Kalaya Changkrueng; Deacha Chatsiriwech

    2011-01-01

    Mixed rare earth nitrates (REi(NO3)3) in the aqueous solution was mixed with tri-n-butyl phosphate (TBP,(n-C4H9O)3PO) dissolved in kerosene for the formation of their corresponding complexes (REi(NO3)3·n1(n-C4H9O)3PO) at 303 K.The effects of initial concentrations of both TBP and mixed rare earth nitrates on the equilibrium constants of their complex formations were investigated.The complexes were formed almost immediately after mixing.The simultaneous formations reached their chemical equilibria within a few minutes by shaking the mixture at 200 r/min.The chemical equilibrium constants of the complex formations were independent of the initial TBP concentrations.However,they were decreased by reducing the concentration of REi(NO3)3.All equilibrium constants of the simultaneous complex formations were less than 0.7,while the average molar ratio of TBP to REi(NO3)3 of the complexes varied between 1.0 and 1.6.The chemical equilibrium constant for the formation of La(NO3)3·(n-C4HgO)3PO was 0.09,while that of Dy(NO3)3·(n-CaH9O)3PO was 0.68.The ascending sequence of chemical equilibrium constants for the simultaneous formations was La,Ce,Pr,Nd,Eu,Y,Srn,Gd,and Dy.

  12. CEQCSY: a new code for chemical equilibrium calculation in multiphased systems

    International Nuclear Information System (INIS)

    As part of the CEC Chemval/mirage project, a method is presented for calculating the thermodynamic equilibrium state of a multiphase system, by minimizing its Gibbs free energy constrained by mass balances. Compared to the other algorithms available in the literature, the method has three main characteristics: - the sets of equations corresponding to the conditions of homogeneous and heterogeneous equilibria are simultaneously solved, - a mathematical criterion for bringing a new multicomponent phase in the system is rigorously demontrated. - It enables a detailed representation of the multisite solid solutions with constraints called site closure relation. The code CEQCSY (Chemical Equilibrium in Complex SYstem) uses this formalism, and works with the thermodynamic data base from the EQ3/6 code. This choice makes easier several compared tests with EQ6: quartz dissolution in water, water-atmospheric air equilibrium, theoretical re-equilibrium of seawater, hydrothermal alteration of granite including solid solutions. The test results demonstrate the high efficiency and velocity of the code CEQCSY, when working on equilibrium state of multiphase systems. This high velocity was the aim of this work, in order to couple with thermic, hydrodynamic or mechanic codes

  13. Pulse-density modulation control of chemical oscillation far from equilibrium in a droplet open-reactor system

    Science.gov (United States)

    Sugiura, Haruka; Ito, Manami; Okuaki, Tomoya; Mori, Yoshihito; Kitahata, Hiroyuki; Takinoue, Masahiro

    2016-01-01

    The design, construction and control of artificial self-organized systems modelled on dynamical behaviours of living systems are important issues in biologically inspired engineering. Such systems are usually based on complex reaction dynamics far from equilibrium; therefore, the control of non-equilibrium conditions is required. Here we report a droplet open-reactor system, based on droplet fusion and fission, that achieves dynamical control over chemical fluxes into/out of the reactor for chemical reactions far from equilibrium. We mathematically reveal that the control mechanism is formulated as pulse-density modulation control of the fusion-fission timing. We produce the droplet open-reactor system using microfluidic technologies and then perform external control and autonomous feedback control over autocatalytic chemical oscillation reactions far from equilibrium. We believe that this system will be valuable for the dynamical control over self-organized phenomena far from equilibrium in chemical and biomedical studies.

  14. Cross-coupling effects in chemically non-equilibrium viscous compressible flows

    Science.gov (United States)

    Kustova, E. V.; Giordano, D.

    2011-01-01

    A closed self-consistent description of a one-temperature non-equilibrium reacting flow is presented on the basis of the kinetic theory methods. A general case including internal degrees of freedom, dissociation-recombination and exchange reactions, and arbitrary values of affinities of chemical reactions is considered. Chemical-reaction rates and mean normal stress in viscous compressible flows are studied and a symmetric cross coupling between these terms is found. It is shown that the rate of each chemical reaction and the mean normal stress depend on velocity divergence and affinities of all chemical reactions; the law of mass action is violated in viscous flows. The results obtained in the frame of linear irreversible thermodynamics can be deduced from the proposed model for the particular case of small affinities. The reciprocal Onsager-Casimir relations are verified, the symmetry of kinetic coefficients is demonstrated, and the entropy production in a viscous flow is studied.

  15. Molecular finite-size effects in stochastic models of equilibrium chemical systems

    Science.gov (United States)

    Cianci, Claudia; Smith, Stephen; Grima, Ramon

    2016-02-01

    The reaction-diffusion master equation (RDME) is a standard modelling approach for understanding stochastic and spatial chemical kinetics. An inherent assumption is that molecules are point-like. Here, we introduce the excluded volume reaction-diffusion master equation (vRDME) which takes into account volume exclusion effects on stochastic kinetics due to a finite molecular radius. We obtain an exact closed form solution of the RDME and of the vRDME for a general chemical system in equilibrium conditions. The difference between the two solutions increases with the ratio of molecular diameter to the compartment length scale. We show that an increase in the fraction of excluded space can (i) lead to deviations from the classical inverse square root law for the noise-strength, (ii) flip the skewness of the probability distribution from right to left-skewed, (iii) shift the equilibrium of bimolecular reactions so that more product molecules are formed, and (iv) strongly modulate the Fano factors and coefficients of variation. These volume exclusion effects are found to be particularly pronounced for chemical species not involved in chemical conservation laws. Finally, we show that statistics obtained using the vRDME are in good agreement with those obtained from Brownian dynamics with excluded volume interactions.

  16. Cross-coupling effects in chemically non-equilibrium viscous compressible flows

    International Nuclear Information System (INIS)

    Graphical abstract: Self-cosistent kinetic-theory description of chemical-reaction rates and mean normal stress in one-temperature viscous compressible gas flows. Reaearch highlights: → In chemically non-equilibrium viscous compressible flows, the rate of each reaction depends on the velocity divergence and rates of all other reactions. → Cross effects between the rates of chemical reactions and normal mean stress can be found in the symmetric form and expressed in terms of the reaction affinities. → In the case of small affinities, the entropy production is unconditionally non-negative; in the case of finite affinities, the entropy production related to the scalar forces has no definite sign. - Abstract: A closed self-consistent description of a one-temperature non-equilibrium reacting flow is presented on the basis of the kinetic theory methods. A general case including internal degrees of freedom, dissociation-recombination and exchange reactions, and arbitrary values of affinities of chemical reactions is considered. Chemical-reaction rates and mean normal stress in viscous compressible flows are studied and a symmetric cross coupling between these terms is found. It is shown that the rate of each chemical reaction and the mean normal stress depend on velocity divergence and affinities of all chemical reactions; the law of mass action is violated in viscous flows. The results obtained in the frame of linear irreversible thermodynamics can be deduced from the proposed model for the particular case of small affinities. The reciprocal Onsager-Casimir relations are verified, the symmetry of kinetic coefficients is demonstrated, and the entropy production in a viscous flow is studied.

  17. Chemical non-equilibrium modelling of an argon-oxygen supersonic ICP

    International Nuclear Information System (INIS)

    In this paper, a non-equilibrium mathematical model for an argon-oxygen inductively coupled plasma (ICP) torch with a supersonic nozzle is developed without making chemical equilibrium assumptions. Reaction rates of dissociation and recombination of diatomic gas and ionization are taken into account. Higher-order approximations of the Chapman-Enskog method are used to obtain better accuracy for transport properties, taking advantage of the most recent sets of collision integrals available in the literature. In order to validate the developed model, results are compared qualitatively and quantitatively with existing experimental data. The calculated results for the axial temperature profile for pure argon less than 10 mm above the substrate are in good agreement with spectroscopic measurements.

  18. Natural Selection and Developmental Constraints in the Evolution of Allometries

    OpenAIRE

    Frankino, W. Anthony; Zwaan, Bas J.; Stern, David L.; Brakefield, Paul M.

    2005-01-01

    In animals, scaling relationships between appendages and body size exhibit high interspecific variation but low intraspecific variation. This pattern could result from natural selection for specific allometries or from developmental constraints on patterns of differential growth. We performed artificial selection on the allometry between forewing area and body size in a butterfly to test for developmental constraints, and then used the resultant increased range of phenotypic variation to quan...

  19. Gas-Kinetic Navier-Stokes Solver for Hypersonic Flows in Thermal and Chemical Non-Equilibrium Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This SBIR project proposes to develop a gas-kinetic Navier-Stokes solver for simulation of hypersonic flows in thermal and chemical non-equilibrium. The...

  20. Development of a thermally and chemically non-equilibrium model for decaying SF6 arc plasmas

    OpenAIRE

    Tanaka, Yasunori; Suzuki, Katsumi; Iijima, Takanori; Shinkai, Takeshi

    2013-01-01

    This paper describes the development of a model with both chemically and thermally non-equilibrium effects in an SF6 arc plasma during decaying phase with transient recovery voltage (TRV) application. The SF 6 arc plasma in decaying phase can be seen in a high voltage SF 6 gas circuit breaker during a large current interruption process. The TRV is often applied to the arc plasma, which may elevate the electron temperature Te than heavy particle temperature Th. This developed model solves ener...

  1. Study of chemical thermodynamic equilibrium of liquid sodium-hydrogen system

    International Nuclear Information System (INIS)

    The study of the thermodynamic equilibrium of the liquid sodium-hydrogen system is carried out on the basis of chemical engineering thermodynamics. The relationship between the hydrogen partial pressure above the surface of liquid sodium and hydrogen concentration in liquid sodium is presented. The quantitative dependence of the Sieverts constant on the temperature is obtained from above. And the experimental data of the Sieverts constant from some references are analyzed. Moreover, the temperature dependence of hydrogen solubility in sodium is given, and the comparison with the experimental data is made

  2. Significance of vapor phase chemical reactions on CVD rates predicted by chemically frozen and local thermochemical equilibrium boundary layer theories

    Science.gov (United States)

    Gokoglu, Suleyman A.

    1988-01-01

    This paper investigates the role played by vapor-phase chemical reactions on CVD rates by comparing the results of two extreme theories developed to predict CVD mass transport rates in the absence of interfacial kinetic barrier: one based on chemically frozen boundary layer and the other based on local thermochemical equilibrium. Both theories consider laminar convective-diffusion boundary layers at high Reynolds numbers and include thermal (Soret) diffusion and variable property effects. As an example, Na2SO4 deposition was studied. It was found that gas phase reactions have no important role on Na2SO4 deposition rates and on the predictions of the theories. The implications of the predictions of the two theories to other CVD systems are discussed.

  3. Chemicals loading in acetylated bamboo assisted by supercritical CO2 based on phase equilibrium data

    Science.gov (United States)

    Silviana, Petermann, M.

    2015-12-01

    Indonesia has a large tropical forest. However, the deforestation still appears annually and vastly. This reason drives a use of bamboo as wood alternative. Recently, there are many modifications of bamboo in order to prolong the shelf life. Unfortunately, the processes need more chemicals and time. Based on wood modification, esterifying of bamboo was undertaken in present of a dense gas, i.e. supercritical CO2. Calculation of chemicals loading referred to ASTM D1413-99 by using the phase equilibrium data at optimum condition by a statistical design. The results showed that the acetylation of bamboo assisted by supercritical CO2 required 14.73 kg acetic anhydride/m3 of bamboo for a treatment of one hour.

  4. Basis invariant description of chemical equilibrium with implications for a recent axionic leptogenesis model

    CERN Document Server

    Shi, Bowen

    2015-01-01

    We provide a systematic treatment of chemical equilibrium in the presence of a specific type of time dependent background. The type of time dependent background we consider appears, for example, in recently proposed axion/Majoron leptogenesis models [1,2]. In describing the chemical equilibrium we use quantities which are invariant under redefinition of fermion phases (we refer to this redefinition as a change of basis for short), and therefore it is a basis invariant treatment. The change of the anomaly terms due to the change of the path integral measure [3,4] under a basis change is taken into account. We find it is useful to go back and forth between different bases, and there are insights which can be more easily obtained in one basis rather than another. A toy model is provided to illustrate the ideas. For the axion leptogenesis model [1], our result suggests that at $T > 10^{13}$ GeV , when sphaleron processes decouple, and $\\Gamma_{B+L} << H < \\Gamma_L$ (where $H$ is the Hubble parameter at t...

  5. Three-dimensional geometric analysis of felid limb bone allometry.

    Directory of Open Access Journals (Sweden)

    Michael Doube

    Full Text Available BACKGROUND: Studies of bone allometry typically use simple measurements taken in a small number of locations per bone; often the midshaft diameter or joint surface area is compared to body mass or bone length. However, bones must fulfil multiple roles simultaneously with minimum cost to the animal while meeting the structural requirements imposed by behaviour and locomotion, and not exceeding its capacity for adaptation and repair. We use entire bone volumes from the forelimbs and hindlimbs of Felidae (cats to investigate regional complexities in bone allometry. METHOD/PRINCIPAL FINDINGS: Computed tomographic (CT images (16435 slices in 116 stacks were made of 9 limb bones from each of 13 individuals of 9 feline species ranging in size from domestic cat (Felis catus to tiger (Panthera tigris. Eleven geometric parameters were calculated for every CT slice and scaling exponents calculated at 5% increments along the entire length of each bone. Three-dimensional moments of inertia were calculated for each bone volume, and spherical radii were measured in the glenoid cavity, humeral head and femoral head. Allometry of the midshaft, moments of inertia and joint radii were determined. Allometry was highly variable and related to local bone function, with joint surfaces and muscle attachment sites generally showing stronger positive allometry than the midshaft. CONCLUSIONS/SIGNIFICANCE: Examining whole bones revealed that bone allometry is strongly affected by regional variations in bone function, presumably through mechanical effects on bone modelling. Bone's phenotypic plasticity may be an advantage during rapid evolutionary divergence by allowing exploitation of the full size range that a morphotype can occupy. Felids show bone allometry rather than postural change across their size range, unlike similar-sized animals.

  6. Fate of polychlorinated biphenyls in a contaminated lake ecosystem: Combining equilibrium passive sampling of sediment and water with total concentration measurements of biota:Chemical equilibrium status of an aquatic ecosystem

    OpenAIRE

    Mäenpää, Kimmo; Leppänen, Matti T.; Figueiredo, Kaisa; Mayer, Philipp; Gilbert, Dorothea; Jahnke, Annika; Gil-Allué, Carmen; Akkanen, Jarkko; Nybom, Inna; Herve, Sirpa

    2015-01-01

    Equilibrium sampling devices can be applied to study and monitor the exposure and fate of hydrophobic organic chemicals on a thermodynamic basis. They can be used to determine freely dissolved concentrations and chemical activity ratios and to predict equilibrium partitioning concentrations of hydrophobic organic chemicals in biota lipids. The authors' aim was to assess the equilibrium status of polychlorinated biphenyls (PCBs) in a contaminated lake ecosystem and along its discharge course u...

  7. Equilibrium thermodynamic analyses of methanol production via a novel Chemical Looping Carbon Arrestor process

    International Nuclear Information System (INIS)

    Highlights: • A novel Chemical Looping Carbon Arrestor Reforming process has been developed. • Energy efficiency of the process is found to be ∼64–70%. • The process emits only about 0.14 mole of carbon dioxide per mole of methanol. • The process offers an efficient and low-emission option for methanol production. - Abstract: Methanol economy is considered as an alternative to hydrogen economy due to the better handling and storage characteristics of methanol fuel than liquid hydrogen. This paper is concerned about a comprehensive equilibrium thermodynamic analysis carried out on methanol production via an innovative Chemical Looping Carbon Arrestor/Reforming process being developed at the University of Newcastle in order to reduce both energy consumption and carbon emissions. The detailed simulation revealed thermodynamic limitations within the Chemical Looping Carbon Reforming process however on the other hand it also confirmed that the new concept is a low energy requirement and low emission option compared to other methanol production technologies. Specifically, the mass and energy balance study showed that the Chemical Looping Carbon Reforming process typically consumes approximately 0.76–0.77 mole methane, 0.25–0.27 mole carbon dioxide, 0.49–0.50 mole water, and 0.51 mole iron oxide (in a chemical looping manner) per mole of methanol production. Moreover, the energy efficiency of Chemical Looping Carbon Reforming process was found to be ∼64–70% and its emission profile was found as low as 0.14 mole carbon dioxide per mole of methanol, which is about 82–88% less than the conventional methanol production process and well below the emission levels of other emerging methanol production technologies

  8. Chemical Equilibrium Modeling of Hanford Waste Tank Processing: Applications of Fundamental Science

    International Nuclear Information System (INIS)

    The development of computational models based upon fundamental science is one means of quantitatively transferring the results of scientific investigations to practical application by engineers in laboratory and field situations. This manuscript describes one example of such efforts, specifically the development and application of chemical equilibrium models to different waste management issues at the U.S. Department of Energy (DOE) Hanford Site. The development of the chemical models is described with an emphasis on the fundamental science investigations that have been undertaken in model development followed by examples of different waste management applications. The waste management issues include the leaching of waste slurries to selective remove non-hazardous components and the separation of Sr90 and transuranics from the waste supernatants. The fundamental science contributions include: molecular simulations of the energetics of different molecular clusters to assist in determining the species present in solution, advanced synchrotron research to determine the chemical form of precipitates, and laser based spectroscopic studies of solutions and solids.

  9. Deviations from chemical equilibrium due to spin-down as an internal heat source in neutron stars

    CERN Document Server

    Reisenegger, A

    1994-01-01

    The core of a neutron star contains several species of particles, whose relative equilibrium concentrations are determined by the local density. As the star spins down, its centrifugal force decreases continuously, and the star contracts. The density of any given fluid element increases, changing its chemical equilibrium state. The relaxation towards the new equilibrium takes a finite time, so the matter is not quite in chemical equilibrium, and energy is stored that can be released by reactions. For a neutron star core composed of neutrons (n), protons (p), and electrons (e), the departure from chemical equilibrium is quantified by the chemical potential difference \\delta\\mu\\equiv \\mu_{\\rm p}+\\mu_{\\rm e} -\\mu_{\\rm n}. A finite \\delta\\mu increases the reaction rates and the neutrino emissivity. If large enough (|\\delta\\mu|\\gta 5kT), it reduces the net cooling rate because some of the stored chemical energy is converted into thermal energy, and can even lead to net heating. A simple model shows the effect of t...

  10. Measurement and Modelling of Phase Equilibrium of Oil - Water - Polar Chemicals

    DEFF Research Database (Denmark)

    Frost, Michael Grynnerup

    . Thesechemicals belong to different families like alcohols, glycols, alkanolamines, surfactants andpolymers. They have various functions, e.g., methanol and MEG are used as gas hydrate inhibitors,surfactants are used to lower interfacial tension between crude oil and microemulsion and polymersin a polymer......As the exploitable resources decrease, more sophisticated recovery methods are employed in the oilindustry to produce the remaining resources. A result of using more sophisticated recovery methodsis that oil field chemicals are more widely used, especially in the offshore oil production...... with the measurement of newexperimental data, but through the development of new experimental equipment for the study ofmulti-phase equilibrium. In addition to measurement of well-defined systems, LLE have beenmeasured for North Sea oils with MEG and water. The work can be split up into two parts: Experimental: VLE...

  11. Review and analysis of high temperature chemical reactions and the effect of non-equilibrium conditions

    Science.gov (United States)

    Johnson, R. E.

    1986-01-01

    Chemical reactions at high temperatures have been considered extensively because of their importance to the heating effects on re-entry of space vehicles. Data on these reactions however, are not abundant and even when found there are discrepancies in data collected by various investigators. In particular, data for recombination reactions are calculated from the dissociation reactions or vice versa through the equilibrium constant. This involves the use of the principle of detailed balancing. This principle is discussed in reference to conditions where it is valid as well as to those where it is not valid. Related topics that merit further study or for which applicable information was available are briefly mentioned in an appendix to this report.

  12. Features of the chemical equilibrium of dimerization in a system of solid spheres

    Science.gov (United States)

    Tkachev, N. K.; Zinatullina, A. R.

    2013-09-01

    Statistical and thermodynamic analyses of the equilibrium of dimerization in solid-phase systems is performed for a model of the Van der Waals type and the Perkus-Yevik approximation. For the model of Van der Waals type, the simple equation γ = exp[ p 0(2-λ3)] is obtained for an average activity coefficient ( p 0 is reduced pressure and λ is bond length in dimer) that describes both positive and negative deviations from the ideal, depending on the change in volume after the elementary act of chemical reaction. It is found that the Perkus-Yevik approximation predicts similar results with more pronounced deviations from the ideal, and the activity coefficient depends on the degree of dissociation as well.

  13. Actinide solubility in deep groundwaters - estimates for upper limits based on chemical equilibrium calculations

    International Nuclear Information System (INIS)

    A chemical equilibrium model is used to estimate maximum upper concentration limits for some actinides (Th, U, Np, Pu, Am) in groundwaters. Eh/pH diagrams for solubility isopleths, dominant dissolved species and limiting solids are constructed for fixed parameter sets including temperature, thermodynamic database, ionic strength and total concentrations of most important inorganic ligands (carbonate, fluoride, phosphate, sulphate, chloride). In order to assess conservative conditions, a reference water is defined with high ligand content and ionic strength, but without competing cations. In addition, actinide oxides and hydroxides are the only solid phases considered. Recommendations for 'safe' upper actinide solubility limits for deep groundwaters are derived from such diagrams, based on the predicted Eh/pH domain. The model results are validated as far as the scarce experimental data permit. (Auth.)

  14. Pulse-density modulation control of chemical oscillation far from equilibrium in a droplet open-reactor system

    OpenAIRE

    Sugiura, Haruka; Ito, Manami; Okuaki, Tomoya; Mori, Yoshihito; Kitahata, Hiroyuki; Takinoue, Masahiro

    2016-01-01

    The design, construction and control of artificial self-organized systems modelled on dynamical behaviours of living systems are important issues in biologically inspired engineering. Such systems are usually based on complex reaction dynamics far from equilibrium; therefore, the control of non-equilibrium conditions is required. Here we report a droplet open-reactor system, based on droplet fusion and fission, that achieves dynamical control over chemical fluxes into/out of the reactor for c...

  15. A new particle-like method for high-speed flows with chemical non-equilibrium

    Directory of Open Access Journals (Sweden)

    Fábio Rodrigues Guzzo

    2010-04-01

    Full Text Available The present work is concerned with the numerical simulation of hypersonic blunt body flows with chemical non-equilibrium. New theoretical and numerical formulations for coupling the chemical reaction to the fluid dynamics are presented and validated. The fluid dynamics is defined for a stationary unstructured mesh and the chemical reaction process is defined for “finite quantities” moving through the stationary mesh. The fluid dynamics is modeled by the Euler equations and the chemical reaction rates by the Arrhenius law. Ideal gases are considered. The thermodynamical data are based on JANNAF tables and Burcat’s database. The algorithm proposed by Liou, known as AUSM+, is implemented in a cell-centered based finite volume method and in an unstructured mesh context. Multidimensional limited MUSCL interpolation method is used to perform property reconstructions and to achieve second-order accuracy in space. The minmod limiter is used. The second order accuracy, five stage, Runge-Kutta time-stepping scheme is employed to perform the time march for the fluid dynamics. The numerical code VODE, which is part of the CHEMKIN-II package, is adopted to perform the time integration for the chemical reaction equations. The freestream reacting fluid is composed of H2 and air at the stoichiometric ratio. The emphasis of the present paper is on the description of the new methodology for handling the coupling of chemical and fluid mechanic processes, and its validation by comparison with the standard time-splitting procedure. The configurations considered are the hypersonic flow over a wedge, in which the oblique detonation wave is induced by an oblique shock wave, and the hypersonic flow over a blunt body. Differences between the solutions obtained with each formulation are presented and discussed, including the effects of grid refinement in each case. The primary objective of such comparisons is the validation of the proposed methodology. Moreover, for

  16. Atomistic-level non-equilibrium model for chemically reactive systems based on steepest-entropy-ascent quantum thermodynamics

    International Nuclear Information System (INIS)

    This paper outlines an atomistic-level framework for modeling the non-equilibrium behavior of chemically reactive systems. The framework called steepest- entropy-ascent quantum thermodynamics (SEA-QT) is based on the paradigm of intrinsic quantum thermodynamic (IQT), which is a theory that unifies quantum mechanics and thermodynamics into a single discipline with wide applications to the study of non-equilibrium phenomena at the atomistic level. SEA-QT is a novel approach for describing the state of chemically reactive systems as well as the kinetic and dynamic features of the reaction process without any assumptions of near-equilibrium states or weak-interactions with a reservoir or bath. Entropy generation is the basis of the dissipation which takes place internal to the system and is, thus, the driving force of the chemical reaction(s). The SEA-QT non-equilibrium model is able to provide detailed information during the reaction process, providing a picture of the changes occurring in key thermodynamic properties (e.g., the instantaneous species concentrations, entropy and entropy generation, reaction coordinate, chemical affinities, reaction rate, etc). As an illustration, the SEA-QT framework is applied to an atomistic-level chemically reactive system governed by the reaction mechanism F + H2 ↔ FH + H

  17. Chemical reaction rates and non-equilibrium pressure of reacting gas mixtures in the state-to-state approach

    International Nuclear Information System (INIS)

    Highlights: • State-to-state approach for coupled vibrational relaxation and chemical reactions. • Self-consistent model for rates of non-equilibrium reactions and energy transitions. • In viscous flows mass action law is violated. • Cross coupling between reaction rates and non-equilibrium pressure in viscous flow. • Results allow implementing the state-to-state approach for viscous flow simulations. - Abstract: Viscous gas flows with vibrational relaxation and chemical reactions in the state-to-state approach are analyzed. A modified Chapman–Enskog method is used for the determination of chemical reaction and vibrational transition rates and non-equilibrium pressure. Constitutive equations depend on the thermodynamic forces: velocity divergence and chemical reaction/transition affinity. As an application, N2 flow with vibrational relaxation across a shock wave is investigated. Two distinct processes occur behind the shock: for small values of the distance the affinity is large and vibrational relaxation is in its initial stage; for large distances the affinity is small and the chemical reaction is in its final stage. The affinity contributes more to the transition rate than the velocity divergence and the effect of these two contributions are more important for small distances from the shock front. For the non-equilibrium pressure, the term associated with the bulk viscosity increases by a small amount the hydrostatic pressure

  18. Ecological allometries and niche use dynamics across Komodo dragon ontogeny

    Science.gov (United States)

    Purwandana, Deni; Ariefiandy, Achmad; Imansyah, M. Jeri; Seno, Aganto; Ciofi, Claudio; Letnic, Mike; Jessop, Tim S.

    2016-04-01

    Ontogenetic allometries in ecological habits and niche use are key responses by which individuals maximize lifetime fitness. Moreover, such allometries have significant implications for how individuals influence population and community dynamics. Here, we examined how body size variation in Komodo dragons ( Varanus komodoensis) influenced ecological allometries in their: (1) prey size preference, (2) daily movement rates, (3) home range area, and (4) subsequent niche use across ontogeny. With increased body mass, Komodo dragons increased prey size with a dramatic switch from small (≤10 kg) to large prey (≥50 kg) in lizards heavier than 20 kg. Rates of foraging movement were described by a non-linear concave down response with lizard increasing hourly movement rates up until ˜20 kg body mass before decreasing daily movement suggesting reduced foraging effort in larger lizards. In contrast, home range area exhibited a sigmoid response with increased body mass. Intrapopulation ecological niche use and overlap were also strongly structured by body size. Thus, ontogenetic allometries suggest Komodo dragon's transition from a highly active foraging mode exploiting small prey through to a less active sit and wait feeding strategy focused on killing large ungulates. Further, our results suggest that as body size increases across ontogeny, the Komodo dragon exhibited marked ontogenetic niche shifts that enabled it to function as an entire vertebrate predator guild by exploiting prey across multiple trophic levels.

  19. Height-diameter allometry of tropical forest trees

    NARCIS (Netherlands)

    Feldpausch, T.R.; Banin, L.; Phillips, O.L.; Baker, T.R.; Lewis, S.L.; Quesada, C.A.; Affum-Baffoe, K.; Arets, E.J.M.M.; Berry, N.J.; Bird, M.; Brondizio, E.S.; Camargo, de P.; Chave, J.; Djagbletey, G.; Domingues, T.F.; Drescher, M.; Fearnside, P.M.; Franca, M.B.; Fyllas, N.M.; Lopez-Gonzalez, G.; Hladik, A.; Higuchi, N.; Hunter, M.O.; Iida, Y.; Salim, K.A.; Kassim, A.R.; Keller, M.; Kemp, J.; King, D.A.; Lovett, J.C.; Marimon, B.S.; Marimon-Junior, B.H.; Lenza, E.; Marshall, A.R.; Metcalfe, D.J.; Mitchard, E.T.A.; Moran, E.F.; Nelson, B.W.; Nilus, R.; Nogueira, E.M.; Palace, M.; Patino, S.; Peh, K.S.H.; Raventos, M.T.; Reitsma, J.M.; Saiz, G.; Schrodt, F.; Sonké, B.; Taedoumg, H.E.; Tan, S.; White, L.; Wöll, H.; Lloyd, J.

    2011-01-01

    Tropical tree height-diameter (H:D) relationships may vary by forest type and region making large-scale estimates of above-ground biomass subject to bias if they ignore these differences in stem allometry. We have therefore developed a new global tropical forest database consisting of 39 955 concurr

  20. Height-diameter allometry of tropical forest trees

    NARCIS (Netherlands)

    Feldpausch, T.R.; Banin, L.; Phillips, O.L.; Baker, T.R.; Lewis, S.L.; Quesada, C.A.; Affum-Baffoe, K.; Arets, E.J.M.M.; Berry, N.J.; Bird, M.; Brondizio, E.S.; Camargo, de P.; Chave, J.; Djagbletey, G.; Domingues, T.F.; Drescher, M.; Fearnside, P.M.; Franca, M.B.; Fyllas, N.M.; Lopez-Gonzalez, G.; Hladik, A.; Higuchi, N.; Hunter, M.O.; Iida, Y.; Salim, K.A.; Kassim, A.R.; Keller, M.; Kemp, J.; King, D.A.; Lovett, J.C.; Marimon, B.S.; Marimon-Junior, B.H.; Lenza, E.; Marshall, A.R.; Metcalfe, D.J.; Mitchard, E.T.A.; Moran, E.F.; Nelson, B.W.; Nilus, R.; Nogueira, E.M.; Palace, M.; Patino, S.; Peh, K.S.H.; Raventos, M.T.; Reitsma, J.M.; Saiz, G.; Schrodt, F.; Sonké, B.; Taedoumg, H.E.; Tan, S.; White, L.; Wöll, H.; Lloyd, J.

    2010-01-01

    Tropical tree height-diameter (H:D) relationships may vary by forest type and region making large-scale estimates of above-ground biomass subject to bias if they ignore these differences in stem allometry. We have therefore developed a new global tropical forest database consisting of 39 955 concurr

  1. Relating urban scaling, fundamental allometry, and density scaling

    CERN Document Server

    Rybski, Diego

    2016-01-01

    We study the connection between urban scaling, fundamental allometry (between city population and city area), and per capita vs.\\ population density scaling. From simple analytical derivations we obtain the relation between the 3 involved exponents. We discuss particular cases and ranges of the exponents which we illustrate in a "phase diagram". As we show, the results are consistent with previous work.

  2. Aruscular mycorhizal fungi alter plant allometry and biomass - density relationships

    DEFF Research Database (Denmark)

    Zhang, Qian; Zhang, Lu; Weiner, Jacob;

    2011-01-01

    fungi (AMF) can promote plant growth and affect plant form. Here experiments were carried out to test whether AMF affect plant allometry and the self-thinning trajectory. Methods Two experiments were conducted on Medicago sativa L., a leguminous species known to be highly dependent on mycorrhiza. Two...

  3. Computer program to solve two-dimensional shock-wave interference problems with an equilibrium chemically reacting air model

    Science.gov (United States)

    Glass, Christopher E.

    1990-01-01

    The computer program EASI, an acronym for Equilibrium Air Shock Interference, was developed to calculate the inviscid flowfield, the maximum surface pressure, and the maximum heat flux produced by six shock wave interference patterns on a 2-D, cylindrical configuration. Thermodynamic properties of the inviscid flowfield are determined using either an 11-specie, 7-reaction equilibrium chemically reacting air model or a calorically perfect air model. The inviscid flowfield is solved using the integral form of the conservation equations. Surface heating calculations at the impingement point for the equilibrium chemically reacting air model use variable transport properties and specific heat. However, for the calorically perfect air model, heating rate calculations use a constant Prandtl number. Sample calculations of the six shock wave interference patterns, a listing of the computer program, and flowcharts of the programming logic are included.

  4. Studying Equilibrium in the Chemical Reaction between Ferric and Iodide Ions in Solution Using a Simple and Inexpensive Approach

    Science.gov (United States)

    Nikolaychuk, Pavel Anatolyevich; Kuvaeva, Alyona Olegovna

    2016-01-01

    A laboratory experiment on the study of the chemical equilibrium based on the reaction between ferric and iodide ions in solution with the formation of ferrous ions, free iodine, and triiodide ions is developed. The total concentration of iodide and triiodide ions in the reaction mixture during the reaction is determined by the argentometric…

  5. Reviewing Some Crucial Concepts of Gibbs Energy in Chemical Equilibrium Using a Computer-Assisted, Guided-Problem-Solving Approach

    Science.gov (United States)

    Borge, Javier

    2015-01-01

    G, G°, ?rG, ?rG°, ?G, and ?G° are essential quantities to master the chemical equilibrium. Although the number of publications devoted to explaining these items is extremely high, it seems that they do not produce the desired effect because some articles and textbooks are still being written with some of these quantities that appear to be…

  6. The role of non-equilibrium fluxes in the relaxation processes of the linear chemical master equation

    International Nuclear Information System (INIS)

    We propose a non-equilibrium thermodynamical description in terms of the Chemical Master Equation (CME) to characterize the dynamics of a chemical cycle chain reaction among m different species. These systems can be closed or open for energy and molecules exchange with the environment, which determines how they relax to the stationary state. Closed systems reach an equilibrium state (characterized by the detailed balance condition (D.B.)), while open systems will reach a non-equilibrium steady state (NESS). The principal difference between D.B. and NESS is due to the presence of chemical fluxes. In the D.B. condition the fluxes are absent while for the NESS case, the chemical fluxes are necessary for the state maintaining. All the biological systems are characterized by their “far from equilibrium behavior,” hence the NESS is a good candidate for a realistic description of the dynamical and thermodynamical properties of living organisms. In this work we consider a CME written in terms of a discrete Kolmogorov forward equation, which lead us to write explicitly the non-equilibrium chemical fluxes. For systems in NESS, we show that there is a non-conservative “external vector field” whose is linearly proportional to the chemical fluxes. We also demonstrate that the modulation of these external fields does not change their stationary distributions, which ensure us to study the same system and outline the differences in the system's behavior when it switches from the D.B. regime to NESS. We were interested to see how the non-equilibrium fluxes influence the relaxation process during the reaching of the stationary distribution. By performing analytical and numerical analysis, our central result is that the presence of the non-equilibrium chemical fluxes reduces the characteristic relaxation time with respect to the D.B. condition. Within a biochemical and biological perspective, this result can be related to the “plasticity property” of biological

  7. A method for incorporating equilibrium chemical reactions into multiphase flow models for CO2 storage

    Science.gov (United States)

    Saaltink, Maarten W.; Vilarrasa, Victor; De Gaspari, Francesca; Silva, Orlando; Carrera, Jesús; Rötting, Tobias S.

    2013-12-01

    CO2 injection and storage in deep saline aquifers involves many coupled processes, including multiphase flow, heat and mass transport, rock deformation and mineral precipitation and dissolution. Coupling is especially critical in carbonate aquifers, where minerals will tend to dissolve in response to the dissolution of CO2 into the brine. The resulting neutralization will drive further dissolution of both CO2 and calcite. This suggests that large cavities may be formed and that proper simulation may require full coupling of reactive transport and multiphase flow. We show that solving the latter may suffice whenever two requirements are met: (1) all reactions can be assumed to occur in equilibrium and (2) the chemical system can be calculated as a function of the state variables of the multiphase flow model (i.e., liquid and gas pressure, and temperature). We redefine the components of multiphase flow codes (traditionally, water and CO2), so that they are conservative for all reactions of the chemical system. This requires modifying the traditional constitutive relationships of the multiphase flow codes, but yields the concentrations of all species and all reaction rates by simply performing speciation and mass balance calculations at the end of each time step. We applied this method to the H2O-CO2-Na-Cl-CaCO3 system, so as to model CO2 injection into a carbonate aquifer containing brine. Results were very similar to those obtained with traditional formulations, which implies that full coupling of reactive transport and multi-phase flow is not really needed for this kind of systems, but the resulting simplifications may make it advisable even for cases where the above requirements are not met. Regarding the behavior of carbonate rocks, we find that porosity development near the injection well is small because of the low solubility of calcite. Moreover, dissolution concentrates at the front of the advancing CO2 plume because the brine below the plume tends to reach

  8. Equilibrium sampling of hydrophobic organic chemicals in sediments: challenges and new approaches

    DEFF Research Database (Denmark)

    Schaefer, S.; Mayer, Philipp; Becker, B.;

    2015-01-01

    coated glass jars were very convenient for routine monitoring campaigns since (1) equilibration times are minimized by the very thin coatings, (2) the equilibration is done in the laboratory and (3) equilibrium sampling is confirmed by equal analyte concentrations in various silicone coating thicknesses...... considered to be the effective concentrations for diffusive uptake and partitioning, and they can be measured by equilibrium sampling. We have thus applied glass jars with multiple coating thicknesses for equilibrium sampling of HOCs in sediment samples from various sites in different German rivers. The...... without tedious time-serious measurements. However, for some sediment samples analyte concentrations decreased towards thicker silicone coating possibly caused by depletion of the sediment or equilibrium partitioning not being attained. In this study, we investigated the application of sediment depletion...

  9. Demonstration of Chemical Equilibrium through Regeneration of Color in Blue Bottle Experiment

    Directory of Open Access Journals (Sweden)

    *R. Azmat

    2011-03-01

    Full Text Available Concept of equilibrium is very difficult to understand for under graduate students. This experiment has a good visual impact of demonstration of equilibrium and would be one way of stimulating awareness in chemistry. An alkaline solution of arabinose and methylene green in aqueous medium can be used to explain equilibrium visually through reaction of dissolved oxygen which was observed in “BLUE BOTTLE EXPERIMENT” that showed the shift of equilibrium by regeneration of color during shaking and upon standing equilibrium shift in the forward direction and color loss was observed. Shaking the solution raises the concentration of oxygen in the mixture and oxidizes the methylene green back to its blue form. When the dissolved oxygen has been consumed, the methylene green is slowly reduced back to its colorless form by the remaining arabinose and the cycle can be repeated many times by further shaking. The experiment was repeated with various concentrations of dye indicator, arabinose and sodium hydroxide concentration. It was observed that regeneration of color and colorloss is the best visual example of explanation of equilibrium.

  10. Competition and allometry in annual halophytes plants: an experience from Crimea

    Directory of Open Access Journals (Sweden)

    Svetlana Zhaldak

    2012-03-01

    Full Text Available Competitive interactions were established in populations of Salicornia perennans, Suaeda acuminata, Halimione pedunculata, Petrosimonia oppositifolia. The competition changed allometry of plants.

  11. Allometry of Sexual Size Dimorphism in Domestic Dog

    OpenAIRE

    Frynta, Daniel; Baudyšová, Jana; Hradcová, Petra; Faltusová, Kateřina; Kratochvíl, Lukáš

    2012-01-01

    Background The tendency for male-larger sexual size dimorphism (SSD) to scale with body size – a pattern termed Rensch's rule – has been empirically supported in many animal lineages. Nevertheless, its theoretical elucidation is a subject of debate. Here, we exploited the extreme morphological variability of domestic dog (Canis familiaris) to gain insights into evolutionary causes of this rule. Methodology/Principal Findings We studied SSD and its allometry among 74 breeds ranging in height f...

  12. Evolution of brain-body allometry in Lake Tanganyika cichlids.

    Science.gov (United States)

    Tsuboi, Masahito; Kotrschal, Alexander; Hayward, Alexander; Buechel, Severine Denise; Zidar, Josefina; Løvlie, Hanne; Kolm, Niclas

    2016-07-01

    Brain size is strongly associated with body size in all vertebrates. This relationship has been hypothesized to be an important constraint on adaptive brain size evolution. The essential assumption behind this idea is that static (i.e., within species) brain-body allometry has low ability to evolve. However, recent studies have reported mixed support for this view. Here, we examine brain-body static allometry in Lake Tanganyika cichlids using a phylogenetic comparative framework. We found considerable variation in the static allometric intercept, which explained the majority of variation in absolute and relative brain size. In contrast, the slope of the brain-body static allometry had relatively low variation, which explained less variation in absolute and relative brain size compared to the intercept and body size. Further examination of the tempo and mode of evolution of static allometric parameters confirmed these observations. Moreover, the estimated evolutionary parameters indicate that the limited observed variation in the static allometric slope could be a result of strong stabilizing selection. Overall, our findings suggest that the brain-body static allometric slope may represent an evolutionary constraint in Lake Tanganyika cichlids. PMID:27241216

  13. The allometry of number of feathers in birds changes seasonally

    Institute of Scientific and Technical Information of China (English)

    Anders Pape Møller

    2015-01-01

    Background:Feathers are a defining feature of birds with multiple functions such as flight, insulation, protection against predation and signaling. Feathers are lost during the annual molt while the rate of such loss at other times of the year and its fitness consequences remain poorly known. Methods:I used information on the number and the mass of feathers for 160 individuals belonging to 85 species of birds in general linear mixed models to analyze allometry of feathers and to investigate possible factors explaining variation in the number of feathers. A phylogenetic effect was assessed by quantifying the random effect of genus. Results:The total mass of feathers increased isometrically with body mass, while the total number of feathers and the mean mass of feathers showed negative allometry. Negative allometry implied that small-sized species had relatively many small feathers. There was a negative association between the number of feathers and migration distance. The total number of feathers initially increased during fall and winter, consistent with individuals growing more feathers later during the year or with individuals with fewer feathers selectively disappearing from the population. In contrast, the number of feathers decreased from winter through spring and summer. Conclusions:These findings suggest that thermoregulation has affected the evolution of the number and the size of feathers, there is selection against feather loss, and that the number of feathers varies across seasons.

  14. The allometry of number of feathers in birds changes seasonally

    Institute of Scientific and Technical Information of China (English)

    Anders; Pape; Mller

    2015-01-01

    Background: Feathers are a defining feature of birds with multiple functions such as flight, insulation, protection against predation and signaling. Feathers are lost during the annual molt while the rate of such loss at other times of the year and its fitness consequences remain poorly known.Methods: I used information on the number and the mass of feathers for 160 individuals belonging to 85 species of birds in general linear mixed models to analyze allometry of feathers and to investigate possible factors explaining variation in the number of feathers. A phylogenetic effect was assessed by quantifying the random effect of genus.Results: The total mass of feathers increased isometrically with body mass, while the total number of feathers and the mean mass of feathers showed negative allometry. Negative allometry implied that small-sized species had relatively many small feathers. There was a negative association between the number of feathers and migration distance. The total number of feathers initially increased during fall and winter, consistent with individuals growing more feathers later during the year or with individuals with fewer feathers selectively disappearing from the population. In contrast, the number of feathers decreased from winter through spring and summer.Conclusions: These findings suggest that thermoregulation has affected the evolution of the number and the size of feathers, there is selection against feather loss, and that the number of feathers varies across seasons.

  15. Equilibrium constraints on buffer erosion based on the chemistry and chemical evolution of glacial meltwaters

    International Nuclear Information System (INIS)

    Document available in extended abstract form only. Colloidal montmorillonite sols could form if the bentonite buffer in a KBS-3 repository for spent nuclear fuel should expand into a fracture and come into contact with dilute glacial meltwaters that have migrated to repository depths from the surface of a warm-based ice sheet. Transport of the sols away from deposition holes in flowing groundwater could conceivably result in significant erosional mass losses of the buffer, thus compromising one or more safety functions assigned to this key engineered barrier. Equilibrium constraints on sol formation were considered in the present study based on observations characterizing the chemistry of sub-glacial meltwaters and the possible chemical evolution of such solutions as they migrate through repository host rocks at Forsmark. Montmorillonite sols are stable under two general limiting conditions: 1) if the concentrations of divalent cations in the colloidal system are below a threshold 'critical coagulation concentration' (CCC) consistent with DLVO theory and the Shulze-Hardy rule, or 2) if monovalent cations occupy a significant fraction of ion-exchange sites. Regarding the first condition, the CCC for Ca2+, the dominant divalent cation in many Swedish groundwaters, is approximately 1 mM. Regarding the second condition, a limited number of experimental studies indicate that montmorillonite sols become unstable, forming gels, if the equivalent fraction, X, of Ca2+ on exchange sites ≥ 0.9. This behaviour results from the effects of ion-ion correlations, which are not accounted for in DLVO theory and which strongly increase the net attraction between colloidal particles having high surface charge and divalent counterions in the electrical double layer. Mass-action constraints for the reaction Ca2+(solution) + 2Na+(montmorillonite) = 2Na+(solution) + Ca2+(montmorillonite) assuming that 1) exchange sites are occupied predominantly by Na+ and/or Ca2+ and 2) the

  16. Phase equilibrium of North Sea oils with polar chemicals: Experiments and CPA modeling

    DEFF Research Database (Denmark)

    Frost, Michael Grynnerup; Kontogeorgis, Georgios M.; von Solms, Nicolas;

    2016-01-01

    This work consists of a combined experimental and modeling study for oil - MEG - water systems, of relevance to petroleum applications. We present new experimental liquid-liquid equilibrium data for the mutual solubility of two North Sea oils + MEG and North Sea oils + MEG + water systems in the...

  17. The Separatory Cylinder: A Novel Solvent Extraction System for the Study of Chemical Equilibrium in Solution.

    Science.gov (United States)

    Cwikel, Dori; And Others

    1986-01-01

    Dicusses the use of the separatory cylinder in student laboratory experiments for investigating equilibrium distribution of a solute between immiscible phases. Describes the procedures for four sets of experiments of this nature. Lists of materials needed and quantities of reagents are provided. (TW)

  18. Application of the Maximum Entropy Principle in the Analysis of a Non-Equilibrium Chemically Reacting Mixture

    Directory of Open Access Journals (Sweden)

    Hameed Metghalchi

    2005-03-01

    Full Text Available The Maximum Entropy Principle has been used to model complex chemical reaction processes. The maximum entropy principle has been employed by the Rate-Controlled Constrained-Equilibrium (RCCE method to determine concentration of different species during non-equilibrium combustion process. In this model, it is assumed that the system evolves through constrained equilibrium states where entropy of the mixture is maximized subject to constraints. Mixture composition is determined by integrating set of differential equations of constraints rather than integration of differential equations for species as is done with detailed kinetics techniques. Since the number of constraints is much smaller than the number of species present, the number of rate equations required to describe the time evolution of the system is considerably reduced. This method has been used to model the stoichiometric mixture of the formaldehyde-oxygen combustion process. In this study 29 species and 139 reactions has been used, while keeping the energy and volume of the system constant. Calculations have been done at different sets of pressures and temperatures, ranging from 1 atm to 100 atm, and from 900 K to 1500 K respectively. Three fixed elemental constraints: conservation of elemental carbon, elemental oxygen and elemental hydrogen and from one to six variable constraints were used. The four to nine rate equations for the constraint potentials (Lagrange multipliers conjugate to the constraints were integrated and as expected, RCCE calculations gave correct equilibrium values in all cases. Only 8 constraints were required to give very good agreement with detailed calculations. Ignition delay times and major species concentrations were within 0.5% to 5% of the values predicted by detailed chemistry calculations. Adding more constraints improved the accuracy of the mole fractions of minor species at early times, but had only a little effect on the ignition delay times. Rate

  19. Surface-dependent chemical equilibrium constants and capacitances for bare and 3-cyanopropyldimethylchlorosilane coated silica nanochannels

    DEFF Research Database (Denmark)

    Andersen, Mathias Bækbo; Frey, Jared; Pennathur, Sumita; Bruus, Henrik

    2011-01-01

    of the electrochemical double layer coupling these two equilibrium models. To validate our model, we used both pH-sensitive dye-based capillary filling experiments as well as electro-osmotic current-monitoring measurements. Using our model we predict the dependence of ζ potential, surface charge...... density, and capillary filling length ratio on ionic strength for different surface compositions, which can be difficult to achieve otherwise....

  20. Parameterization of the Non-Local Thermodynamic Equilibrium Source Function with Chemical Production by an Equivalent Two-Level Model

    Institute of Scientific and Technical Information of China (English)

    XunZHU

    2003-01-01

    The classic two-level or equivalent two-level model that includes only the statistical equilibrium of radiative and thermal processes of excitation and quenching between two vibrational energy levels is extended by adding chemical production to the rate equations. The modifications to the non-local thermodynamic equilibrium source function and cooling rate are parameterized by Φc, which characterizes the ratio of chemical production to collisional quenching. For applications of broadband emission of O3 at 9.6 μm, the non-LTE effect of chemical production on the cooling rate and limb emission is proportional to the ratio of O to O3. For a typical [O]/[O3], the maximum enhancements of limb radiance and cooling rate are about 15%-30% and 0.03-0.05 K day-1, respectively, both occurring near the mesopause regions.This suggests that the broadband limb radiance above ~80 km is sensitive to O3 density but not sensitive to the direct cooling rate along the line-of-sight, which makes O3 retrieval feasible but the direct coolingrate retrieval difficult by using the O3 9.6 μm band limb emission.

  1. Biosorption of Cu (II onto chemically modified waste mycelium of Aspergillus awamori: Equilibrium, kinetics and modeling studies

    Directory of Open Access Journals (Sweden)

    ZDRAVKA VELKOVA

    2012-01-01

    Full Text Available The biosorption potential of chemically modified waste mycelium of industrial xylanase-producing strain Aspergillus awamori for Cu (II removal from aqueous solutions was evaluated. The influence of pH, contact time and initial Cu (II concentration on the removal efficiency was evaluated. Maximum biosorption capacity was reached by sodium hydroxide treated waste fungal mycelium at pH 5.0. The Langmuir adsorption equation matched very well the adsorption equilibrium data in the studied conditions. The process kinetic followed the pseudo-firs order model.

  2. Calculating the mean time to capture for tethered ligands and its effect on the chemical equilibrium of bound ligand pairs.

    Science.gov (United States)

    Shen, Lu; Decker, Caitlin G; Maynard, Heather D; Levine, Alex J

    2016-09-01

    We present here the calculation of the mean time to capture of a tethered ligand to the receptor. This calculation is then used to determine the shift in the partitioning between (1) free, (2) singly bound, and (3) doubly bound ligands in chemical equilibrium as a function of the length of the tether. These calculations are used in the research article Fibroblast Growth Factor 2 Dimer with Superagonist in vitro Activity Improves Granulation Tissue Formation During Wound Healing (Decker et al., in press [1]) to explain quantitatively how changes in polymeric linker length in the ligand dimers modifies the efficacy of these molecules relative to that of free ligands. PMID:27408925

  3. Chemical kinetics and relaxation of non-equilibrium air plasma generated by energetic photon and electron beams

    Science.gov (United States)

    Maulois, Melissa; Ribière, Maxime; Eichwald, Olivier; Yousfi, Mohammed; Azaïs, Bruno

    2016-04-01

    The comprehension of electromagnetic perturbations of electronic devices, due to air plasma-induced electromagnetic field, requires a thorough study on air plasma. In the aim to understand the phenomena at the origin of the formation of non-equilibrium air plasma, we simulate, using a volume average chemical kinetics model (0D model), the time evolution of a non-equilibrium air plasma generated by an energetic X-ray flash. The simulation is undertaken in synthetic air (80% N2 and 20% O2) at ambient temperature and atmospheric pressure. When the X-ray flash crosses the gas, non-relativistic Compton electrons (low energy) and a relativistic Compton electron beam (high energy) are simultaneously generated and interact with the gas. The considered chemical kinetics scheme involves 26 influent species (electrons, positive ions, negative ions, and neutral atoms and molecules in their ground or metastable excited states) reacting following 164 selected reactions. The kinetics model describing the plasma chemistry was coupled to the conservation equation of the electron mean energy, in order to calculate at each time step of the non-equilibrium plasma evolution, the coefficients of reactions involving electrons while the energy of the heavy species (positive and negative ions and neutral atoms and molecules) is assumed remaining close to ambient temperature. It has been shown that it is the relativistic Compton electron beam directly created by the X-ray flash which is mainly responsible for the non-equilibrium plasma formation. Indeed, the low energy electrons (i.e., the non-relativistic ones) directly ejected from molecules by Compton collisions contribute to less than 1% on the creation of electrons in the plasma. In our simulation conditions, a non-equilibrium plasma with a low electron mean energy close to 1 eV and a concentration of charged species close to 1013 cm-3 is formed a few nanoseconds after the peak of X-ray flash intensity. 200 ns after the flash

  4. Mixing and non-equilibrium chemical reaction in a compressible mixing layer. M.S. Thesis Final Report

    Science.gov (United States)

    Steinberger, Craig J.

    1991-01-01

    The effects of compressibility, chemical reaction exothermicity, and non-equilibrium chemical modeling in a reacting plane mixing layer were investigated by means of two dimensional direct numerical simulations. The chemical reaction was irreversible and second order of the type A + B yields Products + Heat. The general governing fluid equations of a compressible reacting flow field were solved by means of high order finite difference methods. Physical effects were then determined by examining the response of the mixing layer to variation of the relevant non-dimensionalized parameters. The simulations show that increased compressibility generally results in a suppressed mixing, and consequently a reduced chemical reaction conversion rate. Reaction heat release was found to enhance mixing at the initial stages of the layer growth, but had a stabilizing effect at later times. The increased stability manifested itself in the suppression or delay of the formation of large coherent structures within the flow. Calculations were performed for a constant rate chemical kinetics model and an Arrhenius type kinetic prototype. The choice of the model was shown to have an effect on the development of the flow. The Arrhenius model caused a greater temperature increase due to reaction than the constant kinetic model. This had the same effect as increasing the exothermicity of the reaction. Localized flame quenching was also observed when the Zeldovich number was relatively large.

  5. Characterization of sodium carboxymethylcellulose-gelatin complex coacervation by chemical analysis of the coacervate and equilibrium fluid phases.

    Science.gov (United States)

    Koh, G L; Tucker, I G

    1988-05-01

    The complex coacervation of sodium carboxymethylcellulose (SCMC) and gelatin has been characterized by chemical analyses of the coacervate and equilibrium fluid phases. The phenol-sulphuric acid (for SCMC) and Lowry (for gelatin) assays were used. Chemically analysed coacervate yield was used to predict optimum coacervation conditions, which occurred at a SCMC-gelatin mixing ratio of 3:7 at pH 3.5. The effects of pH, colloid mixing ratio and total colloid concentration on coacervate yield and composition were studied. The colloid mixing ratio, at which the peak coacervate yields occurred varied with coacervation pH. Increase in the total colloid concentration suppressed coacervation, resulting in a coacervate of higher water content. A similar coacervation mechanism was seen for two viscosity grades SCMC. However, because of the different degree of substitution of these two grades the SCMC-gelatin coacervates had different SCMC contents. PMID:2899623

  6. Molecular finite-size effects in stochastic models of equilibrium chemical systems

    OpenAIRE

    Cianci, Claudia; Smith, Stephen; Grima, Ramon

    2016-01-01

    The reaction-diffusion master equation (RDME) is a standard modelling approach for understanding stochastic and spatial chemical kinetics. An inherent assumption is that molecules are point-like. Here, we introduce the excluded volume reaction-diffusion master equation (vRDME) which takes into account volume exclusion effects on stochastic kinetics due to a finite molecular radius. We obtain an exact closed form solution of the RDME and of the vRDME for a general chemical system in equilibriu...

  7. Prediction of multi-component radioactive waste migration in clay barrier via coupled solute transport and chemical equilibrium speciation

    International Nuclear Information System (INIS)

    Risk assessment of radioactive waste sites require an accurate prediction of geochemical interactions during transport. The prediction of the long-term leaching behaviour of radioactive substances is an increasingly important issue as awareness of the potential future pollution risks associated with management of such wastes grows. An adequate understanding of the numerous and complex processes which may act to retard or mobilise radioactive contaminants along the transport pathway form the repository to the biosphere is necessary. Modelling of the physicochemical processes which take place between the radioactive substances and soil is an invaluable tool as it is often not possible to conduct experiments over sufficiently long time scales in order to observe the long term leaching behaviour of wastes. A COupled Solute Transport and CHemical Equilibrium SPeciation (COSTCHESP) model has been developed. The model has the capability for simulating transport of multiple components of radioactive substances, thermodynamically reacting chemical, through the clay barrier systems. It consists of two main modules, a finite difference transport module (COST), and an equilibrium geochemistry module (CHESP) which is modified version of MINTEQA2. This linearizes the coupling between the physical and chemical processes and leads to a simple and efficient model to simulate the simultaneous processes of advective-dispersive transport (advection; diffusion, osmotic and ion restriction effect) and geochemical reactions (complexation, exchange, precipitation, adsorption and desorption) under different temperature and pressure. The model will lead to proper identification of the form of specific ions ( i.e., adsorbed and precipitated on solid, and available in solution). The proposed model has been simulated for the transport of strontium through compacted bentonite in a multi-component solution at two different temperature. (author)

  8. Development of Bi-phase sodium-oxygen-hydrogen chemical equilibrium calculation program (BISHOP) using Gibbs free energy minimization method

    Energy Technology Data Exchange (ETDEWEB)

    Okano, Yasushi [Japan Nuclear Cycle Development Inst., Oarai, Ibaraki (Japan). Oarai Engineering Center

    1999-08-01

    In order to analyze the reaction heat and compounds due to sodium combustion, the multiphase chemical equilibrium calculation program for chemical reaction among sodium, oxygen and hydrogen is developed in this study. The developed numerical program is named BISHOP; which denotes Bi-Phase, Sodium - Oxygen - Hydrogen, Chemical Equilibrium Calculation Program'. Gibbs free energy minimization method is used because of the special merits that easily add and change chemical species, and generally deal many thermochemical reaction systems in addition to constant temperature and pressure one. Three new methods are developed for solving multi-phase sodium reaction system in this study. One is to construct equation system by simplifying phase, and the other is to expand the Gibbs free energy minimization method into multi-phase system, and the last is to establish the effective searching method for the minimum value. Chemical compounds by the combustion of sodium in the air are calculated using BISHOP. The Calculated temperature and moisture conditions where sodium-oxide and hydroxide are formed qualitatively agree with the experiments. Deformation of sodium hydride is calculated by the program. The estimated result of the relationship between the deformation temperature and pressure closely agree with the well known experimental equation of Roy and Rodgers. It is concluded that BISHOP can be used for evaluated the combustion and deformation behaviors of sodium and its compounds. Hydrogen formation condition of the dump-tank room at the sodium leak event of FBR is quantitatively evaluated by BISHOP. It can be concluded that to keep the temperature of dump-tank room lower is effective method to suppress the formation of hydrogen. In case of choosing the lower inflammability limit of 4.1 mol% as the hydrogen concentration criterion, formation reaction of sodium hydride from sodium and hydrogen is facilitated below the room temperature of 800 K, and concentration of

  9. Development of Bi-phase sodium-oxygen-hydrogen chemical equilibrium calculation program (BISHOP) using Gibbs free energy minimization method

    International Nuclear Information System (INIS)

    In order to analyze the reaction heat and compounds due to sodium combustion, the multiphase chemical equilibrium calculation program for chemical reaction among sodium, oxygen and hydrogen is developed in this study. The developed numerical program is named BISHOP; which denotes Bi-Phase, Sodium - Oxygen - Hydrogen, Chemical Equilibrium Calculation Program'. Gibbs free energy minimization method is used because of the special merits that easily add and change chemical species, and generally deal many thermochemical reaction systems in addition to constant temperature and pressure one. Three new methods are developed for solving multi-phase sodium reaction system in this study. One is to construct equation system by simplifying phase, and the other is to expand the Gibbs free energy minimization method into multi-phase system, and the last is to establish the effective searching method for the minimum value. Chemical compounds by the combustion of sodium in the air are calculated using BISHOP. The Calculated temperature and moisture conditions where sodium-oxide and hydroxide are formed qualitatively agree with the experiments. Deformation of sodium hydride is calculated by the program. The estimated result of the relationship between the deformation temperature and pressure closely agree with the well known experimental equation of Roy and Rodgers. It is concluded that BISHOP can be used for evaluated the combustion and deformation behaviors of sodium and its compounds. Hydrogen formation condition of the dump-tank room at the sodium leak event of FBR is quantitatively evaluated by BISHOP. It can be concluded that to keep the temperature of dump-tank room lower is effective method to suppress the formation of hydrogen. In case of choosing the lower inflammability limit of 4.1 mol% as the hydrogen concentration criterion, formation reaction of sodium hydride from sodium and hydrogen is facilitated below the room temperature of 800 K, and concentration of hydrogen

  10. Equilibrium and thermodynamic studies of Cd (II) biosorption by chemically modified orange peel.

    Science.gov (United States)

    Kumar, Arbind; Kumar, Vipin

    2016-03-01

    Agricultural wastes have great potential of removing heavy metal ions from aqueous solution. Removal of Cd (II) from aqueous solutions onto chemically modified orange peel was studied at different pH, contact time, initial metal concentrations, adsorbent doses and temperature. Batch experiments were carried out under optimized conditions to evaluate the adsorption capacity of orange peel chemically modified with NaOH. The results showed that maximum adsorption capacity of modified orange peel, approximately 97.0%, was observed 3 mg 1⁻¹ of initial Cd(II) concentration pH 6 for 4 g 1⁻¹ adsorbent dosage, 200 min contact time and 298 K temperature. Adsorption efficiency of modified orange peel decreased with increase in temperature indicated exothermic nature of adsorption. A negative value of ΔG⁰(-8.59 kJ mol⁻¹) confirmed the feasibility of adsorption process and spontaneous nature of adsorption. A negative value of ΔH⁰ (-28.08 kJ mol⁻¹) indicated exothermic nature while a negative ΔS⁰ (-66.86 J K⁻¹ mol⁻¹) value suggested decrease in degree of freedom of the adsorbed species. The results showed that biosorption process of Cd(II) ions by chemically modified orange peel is feasible, spontaneous and exothermic under studied conditions. Chemically by modified orange peel investigated in the present study showed good potential for the removal of cadmium from aqueous solutions. PMID:27097438

  11. Description of the equilibrium conditions of chemical reactions in various solvents

    International Nuclear Information System (INIS)

    Empirical knowledge is taken as the basis for establishing a method to predict the equilibrium conditions of reactions of macrocyclic polyethers and monovalent metal cations in various solvents. The reactions in the solvents under review can be well described by the donor number DN according to Gutmann, and by the parameters alpha and pi-asterisk for the H bonding donor and polarity/polarisability, respectively, using a three-parameter equation according to Kamlet/Taft. This applies to both protic and aprotic solvents. The calculations rely on data found in the literature and on own experimental results obtained by microcalorimetric examinations. The evaluation methods evolved for this purpose also allow, by means of additional dilution experiments, to convert the ''integral'', microcalorimetrically obtained complex stability constants, (i.e. those non-discriminating between different types of state such as ions or ion pairs) to the corresponding ''differentiating'' constants (referring to purely ionic quantities), and this applied to the various solvents used. The method does not use foreign ions and can thus also be applied to those cases for which the normal standardisation of reaction conditions published in the literature cannot be maintained (e.g. for reasons of solubility). In some cases it was possible to obtain additional information on the dissociation behaviour of the salts used, which revealed differently strong inclination to form higher aggregations in solution, as shown e.g. by the strong concentration dependence of the salt ion pair dissociation constants obtained. (orig./EF)

  12. Literature survey with chemical equilibrium calculations of bioethanol processing for fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Linares Coderch, X

    2005-07-01

    Bioethanol is being potentially considered as one of the most desirable fossil fuel substitutes. Its subsequent reforming process contributes to obtain hydrogen from a renewable source and, moreover, corroborates the theory that hydrogen fuel cells might become in a near future a truly zero-emission power engine. However, product gas obtained from bioethanol reforming needs to fulfil fuel cell requirements prior to feed the stack. Therefore, this master's thesis deals with bioethanol processing theoretical research. Ethanol production from lignocellulosic biomass is extensively detailed, concentrating on the dilute acid hydrolisis process. Bioethanol processing is conceived as a sum of a reforming process and a further gas cleaning. Steam reforming (STR) is stated as the most developed reforming process nowadays, but partial oxidation (PDX) and autothermal reforming (ATR) are emerging as valuable alternatives. Cleaning system units are helping to reduce CO/CO{sub 2} content in hydrogen gas when feeding fuel cells. Bioethanol processing equilibrium reactionsare simulatedusing HSC software, focusing on hydrogen production via steam reforming. Subsequently, these results are compared with ethanol reforming using both PDX and ATR. STR shows highest hydrogen production, increasing its amount when lowering the water/ethanol ratio at the reformer inlet. ATR leads to the smallest CO amount. Lower amounts could be achieved when using lower reaction temperatures and proper catalysts. Study of pressure influence denotes that is advisable to operate at ambient pressure. (orig.)

  13. Calculation of liquid-liquid equilibrium of aqueous two-phase systems using a chemical-theory-based excess Gibbs energy model

    Directory of Open Access Journals (Sweden)

    Pessôa Filho P. A.

    2004-01-01

    Full Text Available Mixtures containing compounds that undergo hydrogen bonding show large deviations from ideal behavior. These deviations can be accounted for through chemical theory, according to which the formation of a hydrogen bond can be treated as a chemical reaction. This chemical equilibrium needs to be taken into account when applying stability criteria and carrying out phase equilibrium calculations. In this work, we illustrate the application of the stability criteria to establish the conditions under which a liquid-phase split may occur and the subsequent calculation of liquid-liquid equilibrium using a chemical-theory-modified Flory-Huggins equation to describe the non ideality of aqueous two-phase systems composed of poly(ethylene glycol and dextran. The model was found to be able to correlate ternary liquid-liquid diagrams reasonably well by simple adjustment of the polymer-polymer binary interaction parameter.

  14. Evidence for a pseudo chemical equilibrium, restructuration, and porosification in Monte Carlo studies of glass dissolution in water

    International Nuclear Information System (INIS)

    Dissolution of a ternary model of repository glass has been studied by Monte Carlo simulations in two dimensions. The glass is considered as a random homogeneous mixture of three components: weak, like Na2O or B2O3, medium weak, like SiO2, and strong, like ZrO2, according to their decreasing solubility in water At the beginning a rapid dissolution is found which progressively slows down to reach an apparent chemical equilibrium of Silica. However, when the saturation concentration is reached, a steady state porosification process continues at constant speed. This is due to the fact that there is a continuous re-structuration of the system due to the dissolution and recondensation of Silica on the surface of the porous solid. The long term evolution of the process gives a porous material with partial trapping of weak particles. The dynamics of dissolution of weak particles depends )n the ratio of the concentrations of weak to medium weak particles. Two threshold values for the dissolution rate of weak particles have been observed which may be attributed to the change of the effectiveness of the re-structuration process. This study provides a qualitative explanation for the experimentally observed reactivation of the dissolution process when a new piece of glass is put in contact with a solution at equilibrium. (authors)

  15. Adsorptive Removal of Formaldehyde by Chemically Bamboo Activated Carbon with addition of Ag nanoparticle: Equilibrium and Kinetic

    Directory of Open Access Journals (Sweden)

    Pita Rengga Wara Dyah

    2016-01-01

    Full Text Available Carbon was prepared from dried waste bamboo (Dendrocalamus asper using chemical activation with KOH. The carbon was prepared with the activating agent in a mass ratio of KOH and dried bamboo (3:1 at 800oC. Using impregnation technique, the bamboo-based activated carbon has developed with modified Ag nanoparticle (Ag-AC to capture formaldehyde. The Ag-AC has characteristics of moderate surface area of 685 m2/g and average pore size of 2.7 nm. The adsorption equilibriums and kinetics of formaldehyde on Ag-AC measured. The influences of initial formaldehyde on adsorption performance have measured in a batch system. The equilibrium data were evaluated by isotherm models of Langmuir, Freundlich, and Temkin. The Langmuir model well describes the adsorptive removal of formaldehyde on Ag-AC in this study. Pseudo-first-order and pseudo-second-order kinetic equations were applied to test the experimental data. The pseudo-second-order exhibited the best fit for kinetic study.

  16. Students misconceptions on chemical equilibrium and their consequences to biochemistry learning

    Directory of Open Access Journals (Sweden)

    E. Montagna

    2011-04-01

    Full Text Available It is well documented that misconceptions onchemical equilibrium (CE are widespread among students in  higher education. Nevertheless CE concept is critical for biochemistry topics development such as buffer solutions, enzymekinetics, allosteric enzymes, metabolic networks, among others. In the present work weperformed tests in order to diagnose howstudents use the concepts of CE acquired inother courses. We tested high school andundergraduate students from two courses intwo institutions, in four moments of their course: a. freshmen; b. after basic general chemistry courses; c. along the biochemistrycourse and d. after physical chemistry courses. The tests dealt with: 1. tasks containing current terms, keywords and concepts about CE; 2. tests that exclusively use symbolic representations of CE and 3. application of elementary concepts of CE in biochemistry. The resultsshow that among thestudents: 1. more than 95% correctly answer questions of group1; 2. more than 50% fail in questions of group 2, and; 3. morethan 50% fail in questions of the group 3. We conclude that students solve tests  on CE without really understand the concepts involved; consequently studentsare unable to work CE concepts without mathematical tools or conventional formulas.Finally, the results show that students are restricted to use CE concept only in the context in which it was learned and this certainly impairs the significant learning of the forthcoming biochemical contents.

  17. Parameterization of the Non-Local Thermodynamic Equilibrium Source Function with Chemical Production by an Equivalent Two-Level Model

    Institute of Scientific and Technical Information of China (English)

    Xun ZHU

    2003-01-01

    The classic two-level or equivalent two-level model that includes only the statistical equilibriumof radiative and thermal processes of excitation and quenching between two vibrational energy levelsis extended by adding chemical production to the rate equations. The modifications to the non-localthermodynamic equilibrium source function and cooling rate are parameterized by φc, which characterizesthe ratio of chemical production to collisional quenching. For applications of broadband emission of O3 at9.6 μm, the non-LTE effect of chemical production on the cooling rate and limb emission is proportionalto the ratio of O to O3. For a typical [O]/[O3], the maximum enhancements of limb radiance and coolingrate are about 15%-30% and 0.03-0.05 K day-1, respectively, both occurring near the mesopause regions.This suggests that the broadband limb radiance above ~80 km is sensitive to O3 density but not sensitiveto the direct cooling rate along the line-of-sight, which makes O3 retrieval feasible but the direct coolingrate retrieval difficult by using the O3 9.6 μm band limb emission.

  18. Primate facial allometry and interpretations of australopithecine variation.

    Science.gov (United States)

    Corruccini, R S; Ciochon, R L

    1979-09-01

    Pilbeam and Gould have discussed African Plio-Pleistocene hominid evolution in the context of allometry (size-dependent morphological change). These authors demonstrate that some general aspects of australopithecine morphology (tooth, brain and body size) support the hypothesis that certain early African hominids were merely scaled variations of each other at different sizes. They also speculate that the methods applied to these very broad anatomical categories can be extended to more specific and detailed traits, especially in the face and cranium. Such traits underlie most taxonomic and phylogenetic discussions of the early African Hominidae, so it is useful to follow Pilbeam and Gould's lead, as we do here, and investigate the structural differences in the australopithecine face and cranimum in a quantificiable fashion. PMID:121762

  19. PACKAGE (Plasma Analysis, Chemical Kinetics and Generator Efficiency): a computer program for the calculation of partial chemical equilibrium/partial chemical rate controlled composition of multiphased mixtures under one dimensional steady flow

    Energy Technology Data Exchange (ETDEWEB)

    Yousefian, V.; Weinberg, M.H.; Haimes, R.

    1980-02-01

    The NASA CEC Code was the starting point for PACKAGE, whose function is to evaluate the composition of a multiphase combustion product mixture under the following chemical conditions: (1) total equilibrium with pure condensed species; (2) total equilibrium with ideal liquid solution; (3) partial equilibrium/partial finite rate chemistry; and (4) fully finite rate chemistry. The last three conditions were developed to treat the evolution of complex mixtures such as coal combustion products. The thermodynamic variable pairs considered are either pressure (P) and enthalpy, P and entropy, at P and temperature. Minimization of Gibbs free energy is used. This report gives detailed discussions of formulation and input/output information used in the code. Sample problems are given. The code development, description, and current programming constraints are discussed. (DLC)

  20. Estimation of Equilibrium Liquid from the Pyroxene Chemical Compositions of Monomict and Polymict Cumulate Eucrites

    Science.gov (United States)

    Saiki, K.; Takeda, H.

    1993-07-01

    Cumulate eucrites have bulk compositions between diogenites and ordinary (noncumulate) eucrites (OE). The study of polymict eucrite Y791439 shows that ordinary to cumulate eucrites are located adjacent to each other in the parent body crust, and shows that there are four stages in the crystallization sequence of pyroxene, including two types of cumulate eucrite [1]. In this study we calculate the activities of some elements in the liquid equilibrated with pyroxenes in Y791439 and some cumulate eucrites by single element partition coefficients for the better understanding of the liquid evolution on the HED parent body's crust. Polished thin sections (PTS) of Y791439,51 and Y791195,92-1 were supplied from the National Institute of Polar Research (NIPR) in Japan. Medanitos was supplied from the British Museum of Natural History. A PTS of ALH85001 was made from a chip supplied from Meteorite Working Group (MWG) in the U.S. These PTSs were investigated by SEM (JEOL840A) equipped with a chemical mapping system (PXQUAD system) originally constructed by us and the chemical compositions of pyroxenes were obtained by EPMA (JEOL 733 mark II). Y791439 is composed of four types of pyroxene; JV (Juvinas), MC (Moore County), BD (Binda), and D (Diogenite)-type in order from Fe-rich to Mg-rich. The activities of some network-modifier elements (e.g., Fe, Mg, and Ca) in the liquid equilibrated with the pyroxenes in Y791439 are calculated and plotted in the Ca/Fe vs. Mg/Fe (atomic ratio) diagram. For the calculation we adopted the modified Bottinga-Weill two-lattice melt model [2] and single "M"-site pyroxene model and applied Nielsen-Drake partition coefficients [3]. The bulk chemical composition of Y7308 is taken from Ikeda and Takeda (1985) and those of the other meteorites are taken from BVSP (1981). The bulk of Y7308 is one of the probable candidates for the parental liquid that crystallized diogenites and eucrites and the bulks of OE are candidates for the most evolved liquid

  1. Quantum chemical modeling of humic acid/air equilibrium partitioning of organic vapors.

    Science.gov (United States)

    Niederer, Christian; Goss, Kai-Uwe

    2007-05-15

    Classical approaches for predicting soil organic matter partition coefficients of organic compounds require a calibration with experimental partition data and, for good accuracy, experimental compound descriptors. In this study we evaluate the quantum chemical model COSMO-RS in its COSMOtherm implementation for the prediction of about 200 experimental Leonardite humic acid/air partition coefficients without calibration or experimental compound descriptors, but simply based on molecular structures. For this purpose a Leonardite Humic Acid model monomer limited to 31 carbon atoms was derived from 13C NMR analysis, elemental analysis, and acidic function analysis provided in the literature. Altogether the COSMOtherm calculations showed a good performance and we conclude that it may become a very promising tool for the prediction of sorption in soil organic matter for compounds for which the molecular structure is the only reliable information available. COSMOtherm can be expected to be very robust with respectto new and complex compound structures because its calculations are based on a fundamental assessment of the underlying intermolecular forces. In contrast, other empirical models that are also based on the molecular structure of the sorbate have an application domain that is limited by their calibration data set that is often unknown to the user. PMID:17547191

  2. ADSORPTION CHARACTERIZATION OF CO(II IONS ONTO CHEMICALLY TREATED QUERCUS COCCIFERA SHELL: EQUILIBRIUM, KINETIC AND THERMODYNAMIC STUDIES

    Directory of Open Access Journals (Sweden)

    M. Hamdi Karaoglu

    2011-04-01

    Full Text Available Quercus coccifera shell (QCS, a relatively abundant and inexpensive material, is currently being investigated as an adsorbent to remove cobalt(II from water. Before the adsorption experiments, QCS was subjected to chemical treatment to provide maximum surface area. Then, the kinetics and adsorption mechanism of Co(II ions on QCS were studied using different parameters such as adsorbent dosage, initial concentration, temperature, contact time, and solution pH. The loaded metals could be desorbed effectively with dilute hydrochloric acid, nitric acid, and 0.1 M EDTA. The Langmuir and Freundlich models were used to describe the uptake of cobalt on QCS. The equilibrium adsorption data were better fitted to Langmuir adsorption isotherm model. The maximum adsorption capacity (qm of QCS for Co(II was 33 mg g-1. Various kinetic models were used to describe the adsorption process. The adsorption followed pseudo second-order kinetic model. The intraparticle diffusion was found to be the rate-limiting step in the adsorption process. The diffusion coefficients were calculated and found to be in the range of 3.11×10−6 to 168.78×10−6 cm2s-1. The negative DH* value indicated exothermic nature of the adsorption.

  3. Prediction of the Chapman-Jouguet chemical equilibrium state in a detonation wave from first principles based reactive molecular dynamics.

    Science.gov (United States)

    Guo, Dezhou; Zybin, Sergey V; An, Qi; Goddard, William A; Huang, Fenglei

    2016-01-21

    The combustion or detonation of reacting materials at high temperature and pressure can be characterized by the Chapman-Jouguet (CJ) state that describes the chemical equilibrium of the products at the end of the reaction zone of the detonation wave for sustained detonation. This provides the critical properties and product kinetics for input to macroscale continuum simulations of energetic materials. We propose the ReaxFF Reactive Dynamics to CJ point protocol (Rx2CJ) for predicting the CJ state parameters, providing the means to predict the performance of new materials prior to synthesis and characterization, allowing the simulation based design to be done in silico. Our Rx2CJ method is based on atomistic reactive molecular dynamics (RMD) using the QM-derived ReaxFF force field. We validate this method here by predicting the CJ point and detonation products for three typical energetic materials. We find good agreement between the predicted and experimental detonation velocities, indicating that this method can reliably predict the CJ state using modest levels of computation. PMID:26688211

  4. The chemical equilibrium under non-ideal conditions: industrial applications; El equilibrio quimico bajo condiciones no ideales: aplicaciones industriales

    Energy Technology Data Exchange (ETDEWEB)

    Silva Martinez, Susana; Alvarez Gallegos, Alberto; Quere, Alain [Instituto de Investigaciones Electricas, Cuernavaca (Mexico)

    1993-05-01

    In this paper is described the application of a computer program to the chemical equilibrium in non-ideal conditions (aqueous solutions of multicomponent electrolytes in the ionic forces interval: 0 < 1 < 6 mol/Kg H{sub 2}O and temperatures close to 25 celsius degrees), and its importance at industrial scale. The calculation of the thermodynamic properties of the solution (activity coefficients, osmotic coefficient, and water activity) is based in one of the most modern theories of the electrolytes; the theoretical results, compared with the experimental ones have an error of 10% or better. [Espanol] En este trabajo se describe la aplicacion de un programa de computo al equilibrio quimico en condiciones no ideales (soluciones acuosas de electrolitos multicomponentes en el intervalo de fuerzas ionicas: 0 < 1 < 6 mol/Kg H{sub 2}O y temperaturas cercanas a 25 grados celsius) y su importancia a escala industrial. El calculo de las propiedades termodinamicas (coeficientes de actividad, coeficiente osmotico y actividad del agua) de la solucion, esta basado en una de las teorias mas modernas de los electrolitos; los resultados teoricos comparados con los experimentales tienen un error del 10% o mejor.

  5. Temperature-mediated transitions between isometry and allometry in a colonial, modular invertebrate.

    Science.gov (United States)

    Edmunds, Peter J

    2006-09-22

    The evolutionary success of animal design is strongly affected by scaling and virtually all metazoans are constrained by allometry. One body plan that appears to relax these constraints is a colonial modular (CM) design, in which modular iteration is hypothesized to support isometry and indeterminate colony size. In this study, growth rates of juvenile scleractinians (less than 40mm diameter) with a CM design were used to test this assertion using colony diameters recorded annually for a decade and scaling exponents (b) for growth calculated from double logarithmic plots of final versus initial diameters. For all juvenile corals, b differed significantly among years, with isometry (b=1) in 4 years, but positive allometry (b>1) in 5 years. The study years were characterized by differences in seawater temperature that were associated significantly with b for growth, with isometry in warm years but positive allometry in cool years. These results illustrate variable growth scaling in a CM taxon and suggest that the switch between scaling modes is mediated by temperature. For the corals studied, growth was not constrained by size, but this outcome was achieved through both isometry and positive allometry. Under cooler conditions, positive allometry may be beneficial as it represents a growth advantage that increases with size. PMID:16928628

  6. Male mate choice scales female ornament allometry in a cichlid fish

    Directory of Open Access Journals (Sweden)

    Kullmann Harald

    2010-10-01

    Full Text Available Abstract Background Studies addressing the adaptive significance of female ornamentation have gained ground recently. However, the expression of female ornaments in relation to body size, known as trait allometry, still remains unexplored. Here, we investigated the allometry of a conspicuous female ornament in Pelvicachromis taeniatus, a biparental cichlid that shows mutual mate choice and ornamentation. Females feature an eye-catching pelvic fin greatly differing from that of males. Results We show that allometry of the female pelvic fin is scaled more positively in comparison to other fins. The pelvic fin exhibits isometry, whereas the other fins (except the caudal fin show negative allometry. The size of the pelvic fin might be exaggerated by male choice because males prefer female stimuli that show a larger extension of the trait. Female pelvic fin size is correlated with individual condition, suggesting that males can assess direct and indirect benefits. Conclusions The absence of positive ornament allometry might be a result of sexual selection constricted by natural selection: fins are related to locomotion and thus may be subject to viability selection. Our study provides evidence that male mate choice might scale the expression of a female sexual ornament, and therefore has implications for the understanding of the relationship of female sexual traits with body size in species with conventional sex-roles.

  7. The use of a hot cyclone for separation of heavy metals during combustion, evaluation by chemical equilibrium calculations

    International Nuclear Information System (INIS)

    This degree-project is a part of a project financed by the European Communities non Nuclear energy program. The aim of the project is to reach a sustainable use of biofuels as energy source. A requirement for sustainable use of biomass fuel in combustion and gasification plants is that the ash produced can be recycled back to the forest and farmlands in a safe and controlled way. Recycling is important because most of the nutrients (Ca, Mg, P, Na and K) are ending up in the ash. However, the ashes also contain heavy metals and organic pollutants that should not be recycled. To solve this problem, a new technique for separation of the heavy metals during combustion is under development. This technique builds on evaporation of heavy metals and particle separation with a hot cyclone. The idea is that the heavy metal will pass the cyclone as gas species while the nutrients will be separated in the cyclone from the flue gas. The heavy metals are then collected in the more efficient cleaning device downstream in the process. In the present study, the technique has been evaluated by chemical equilibrium calculations and the results were compared with some previously performed full-scale experiments. The results show that by this technique a separation of Cd and Pb will be possible. Concerning the elements As, Cu and Cr, it may be possible to separate them to some extent while the element Ni and V will not be separated. At least 60-70% of Na and K and 90% of Ca, Mg and P will be separated in the cyclone 21 refs, 12 figs, 2 tabs

  8. Chemical Equilibrium of Aluminate in Hanford Tank Waste Originating from Tanks 241-AN-105 and 241-AP-108

    Energy Technology Data Exchange (ETDEWEB)

    McCoskey, Jacob K. [Washington River Protection Solutions LLC, Richland, WA (United States); Cooke, Gary A. [Washington River Protection Solutions LLC, Richland, WA (United States); Herting, Daniel L. [Washington River Protection Solutions LLC, Richland, WA (United States)

    2015-09-23

    The purposes of the study described in this document follow; Determine or estimate the thermodynamic equilibrium of gibbsite in contact with two real tank waste supernatant liquids through both dissolution of gibbsite (bottom-up approach) and precipitation of aluminum-bearing solids (top-down approach); determine or estimate the thermodynamic equilibrium of a mixture of gibbsite and real tank waste saltcake in contact with real tank waste supernatant liquid through both dissolution of gibbsite and precipitation of aluminum-bearing solids; and characterize the solids present after equilibrium and precipitation of aluminum-bearing solids.

  9. Height-diameter allometry of tropical forest trees

    Directory of Open Access Journals (Sweden)

    T. R. Feldpausch

    2011-05-01

    Full Text Available Tropical tree height-diameter (H:D relationships may vary by forest type and region making large-scale estimates of above-ground biomass subject to bias if they ignore these differences in stem allometry. We have therefore developed a new global tropical forest database consisting of 39 955 concurrent H and D measurements encompassing 283 sites in 22 tropical countries. Utilising this database, our objectives were:

    1. to determine if H:D relationships differ by geographic region and forest type (wet to dry forests, including zones of tension where forest and savanna overlap.

    2. to ascertain if the H:D relationship is modulated by climate and/or forest structural characteristics (e.g. stand-level basal area, A.

    3. to develop H:D allometric equations and evaluate biases to reduce error in future local-to-global estimates of tropical forest biomass.

    Annual precipitation coefficient of variation (PV, dry season length (SD, and mean annual air temperature (TA emerged as key drivers of variation in H:D relationships at the pantropical and region scales. Vegetation structure also played a role with trees in forests of a high A being, on average, taller at any given D. After the effects of environment and forest structure are taken into account, two main regional groups can be identified. Forests in Asia, Africa and the Guyana Shield all have, on average, similar H:D relationships, but with trees in the forests of much of the Amazon Basin and tropical Australia typically being shorter at any given D than their counterparts elsewhere. The region-environment-structure model with the lowest Akaike's information criterion and lowest deviation estimated stand-level H across all plots to within amedian −2.7 to 0.9% of the true value. Some of the plot-to-plot variability in

  10. Height-diameter allometry of tropical forest trees

    Directory of Open Access Journals (Sweden)

    T. R. Feldpausch

    2010-10-01

    Full Text Available Tropical tree height-diameter (H:D relationships may vary by forest type and region making large-scale estimates of above-ground biomass subject to bias if they ignore these differences in stem allometry. We have therefore developed a new global tropical forest database consisting of 39 955 concurrent H and D measurements encompassing 283 sites in 22 tropical countries. Utilising this database, our objectives were:

      1. to determine if H:D relationships differ by geographic region and forest type (wet to dry forests, including zones of tension where forest and savanna overlap.

      2. to ascertain if the H:D relationship is modulated by climate and/or forest structural characteristics (e.g. stand-level basal area, A.

      3. to develop H:D allometric equations and evaluate biases to reduce error in future local-to-global estimates of tropical forest biomass.

    Annual precipitation coefficient of variation (PV, dry season length (SD, and mean annual air temperature (TA emerged as key drivers of variation in H:D relationships at the pantropical and region scales. Vegetation structure also played a role with trees in forests of a high A being, on average, taller at any given D. After the effects of environment and forest structure are taken into account, two main regional groups can be identified. Forests in Asia, Africa and the Guyana Shield all have, on average, similar H:D relationships, but with trees in the forests of much of the Amazon Basin and tropical Australia typically being shorter at any given D than their counterparts elsewhere.

    The region-environment-structure model with the lowest Akaike's information criterion and lowest deviation estimated stand-level H across all plots to within a median –2.7 to 0.9% of the true value. Some of the plot

  11. BAAD: a Biomass And Allometry Database for woody plants

    Energy Technology Data Exchange (ETDEWEB)

    Falster, Daniel; Duursma, Remko; Ishihara, Masae; Barneche, Diego; Fitzjohn, Richard; Varhammar, Angelica; Aiba, Masahiro; Ando, M.; Anten, Niels; Aspinwall, Michael J.; Baltzer, Jennifer; Baraloto, Christopher; Battaglia, Michael; Battles, John; Bond-Lamberty, Benjamin; van Breugel, Michiel; Camac, James; Claveau, Yves; Coll Mir, Llus; Dannoura, Dannoura; Delagrange, Sylvain; Domec, Jean-Cristophe; Fatemi, Farrah; Feng, Wang; Gargaglione, Veronica; Goto, Yoshiaki; Hagihara, Akio; Hall, Jefferson S.; Hamilton, Steve; Harja, Degi; Hiura, Tsutom; Holdaway, Robert; Hutley, L. B.; Ichie, Tomoaki; Jokela, Eric; Kantola, Anu; Kelly, Jeffery W.; Kenzo, Tanaka; King, David A.; Kloeppel, Brian; Kohyama, Takashi; Komiyama, Akira; Laclau, Jean-Paul; Lusk, Christopher; Maguire, Doug; le Maire, Guerric; Makela, Annikki; Markesteijn, Lars; Marshall, John; McCulloh, Kate; Miyata, Itsuo; Mokany, Karen; Mori, Shigeta; Myster, Randall; Nagano, Masahiro; Naidu, Shawna; Nouvellon, Yann; O' Grady, Anthony; O' Hara, Kevin; Ohtsuka, Toshiyuki; Osada, Noriyuki; Osunkoya, Olusegun O.; Luis Peri, Pablo; Petritan, Mary; Poorter, Lourens; Portsmuth, Angelika; Potvin, Catherine; Ransijn, Johannes; Reid, Douglas; Ribeiro, Sabina C.; Roberts, Scott; Rodriguez, Rolando; Saldana-Acosta, Angela; Santa-Regina, Ignacio; Sasa, Kaichiro; Gailia Selaya, Nadezhda; Sillett, Stephen; Sterck, Frank; Takagi, Kentaro; Tange, Takeshi; Tanouchi, Hiroyuki; Tissue, David; Umehara, Tohru; Utsugi, Hajime; Vadeboncoeur, Matthew; Valladares, Fernando; Vanninen, Petteri; Wang, Jian; Wenk, Elizabeth; Williams, Dick; Ximenes, Fabiano de Aquino; Yamaba, Atsushi; Yamada, Toshihiro; Yamakura, Takuo; Yanai, Ruth; York, Robert

    2015-05-07

    Quantifying the amount of mass or energy invested in plant tissues is of fundamental interest across a range of disciplines, including ecology, forestry, ecosystem science, and climate change science (Niklas, 1994; Chave et al. 2005; Falster et al. 2011). The allocation of net primary production into different plant components is an important process affecting the lifetime of carbon in ecosystems, and resource use and productivity by plants (Cannell & Dewar, 1994; Litton et al. 2007; Poorter et al. 2012). While many studies in have destructively harvested woody plants in the name of science, most of these data have only been made available in the form of summary tables or figures included in publications. Until now, the raw data has resided piecemeal on the hard drives of individual scientists spread around the world. Several studies have gathered together the fitted (allometric) equations for separate datasets (Ter-Mikaelian & Korzukhin, 1997; Jenkins et al. 2003; Zianis et al. 2005; Henry et al. 2013), but none have previously attempted to organize and share the raw individual plant data underpinning these equations on a large scale. Gathered together, such data would represent an important resource for the community, meeting a widely recognised need for rich, open data resources to solve ecological problems (Costello et al. 2013; Fady et al. 2014; Harfoot & Roberts, 2014; Costello et al. 2013). We (D.S. Falster and R.A. Duursma, with the help of D.R. Barneche, R.G. FitzJohn and A. Vårhammar) set out to create such a resource, by asking authors directly whether they would be willing to make their raw data files freely available. The response was overwhelming: nearly everyone we contacted was interested to contribute their raw data. Moreover, we were invited to incorporate another compilation led by M. Ishihara and focussing on Japanese literature. As a result, we present BAAD: a Biomass And Allometry Database for woody plants, comprising data collected in 174

  12. Allometry of the duration of flight feather molt in birds.

    Directory of Open Access Journals (Sweden)

    Sievert Rohwer

    2009-06-01

    Full Text Available We used allometric scaling to explain why the regular replacement of the primary flight feathers requires disproportionately more time for large birds. Primary growth rate scales to mass (M as M(0.171, whereas the summed length of the primaries scales almost twice as fast (M(0.316. The ratio of length (mm to rate (mm/day, which would be the time needed to replace all the primaries one by one, increases as the 0.14 power of mass (M(0.316/M(0.171 = M(0.145, illustrating why the time required to replace the primaries is so important to life history evolution in large birds. Smaller birds generally replace all their flight feathers annually, but larger birds that fly while renewing their primaries often extend the primary molt over two or more years. Most flying birds exhibit one of three fundamentally different modes of primary replacement, and the size distributions of birds associated with these replacement modes suggest that birds that replace their primaries in a single wave of molt cannot approach the size of the largest flying birds without first transitioning to a more complex mode of primary replacement. Finally, we propose two models that could account for the 1/6 power allometry between feather growth rate and body mass, both based on a length-to-surface relationship that transforms the linear, cylindrical growing region responsible for producing feather tissue into an essentially two-dimensional structure. These allometric relationships offer a general explanation for flight feather replacement requiring disproportionately more time for large birds.

  13. Evaluating the Importance of Local Environment on Tree Structural Allometries

    Science.gov (United States)

    Duncanson, L.; Cook, B. D.; Rourke, O.; Hurtt, G. C.; Dubayah, R.

    2013-12-01

    Allometric relationships relating various forest structural properties such as DBH, tree height and aboveground biomass have been developed through detailed field data collection both in the United States, and globally. However, there has been limited attention to explaining observed variability in these relationships. Often, a single relationship is developed for a single species, and is applied irrespective of environment. In this research, we attempt to explain allometry as a function of environment by focusing on the relationship between DBH, crown radius and tree height. Two primary datasets are used to conduct this research. First, the Forest Inventory Analysis (FIA) dataset, including tree DBH and height information for the United States, are used to investigate variability in the relationship between DBH and tree height. Second, high-resolution airborne lidar datasets were collected from areas across the US, Canada and Costa Rica and are applied to investigate variability in the relationship between crown radius and height. The lidar datasets are run through a generalized canopy delineation algorithm to produce multilayered estimates of individual tree location, height, and crown radius. Power law functions are fit to the relationships between DBH and tree height, and crown radius and tree height. The mean and standard deviation of the power law exponents are compared to environmental attributes including precipitation, temperature, topography, and age since disturbance. This research demonstrates that although universal tendencies are observed in average power law exponents, considerable local variability exists that can be partially attributed to local environment. Therefore local environment, as well as tree species, should be accounted for in the development and application of allometric equations for forest studies.

  14. Accounting robustly for instantaneous chemical equilibriums in reactive transport: A numerical method and its application to liquid-liquid extraction modeling

    International Nuclear Information System (INIS)

    Reactive transport equations are used in numerous application fields: CO2 or nuclear waste storage monitoring, separation processes in chemical engineering. We present a general method to account robustly for instantaneous chemical equilibriums in reactive transport. This method is adapted to all kinds of hydraulic transport models including 1D to 3D convection-diffusion equations. This leads to the resolution of a bound constrained system of Differential Algebraic Equations (DAEs). The algebraic constraints come from the adjunction of mass action laws related to the equilibriums, whereas the bounds account for the positivity of the computed quantities. In order to solve the numerical system associated with our method, we use an adaptation of the DASSL solver, CDASSL, that can handle the resolution of bound constrained DAE systems. We present an application of this method to liquid-liquid extraction modeling. Numerical experiments demonstrate the interest of using the CDASSL solver to ensure the bound constraints are satisfied. (authors)

  15. 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

  16. Candidates Profile in FUVEST Exams from 2004 to 2013: Private and Public School Distribution, FUVEST Average Performance and Chemical Equilibrium Tasks Performance

    Directory of Open Access Journals (Sweden)

    R.S.A.P. Oliveira

    2014-08-01

    Full Text Available INTRODUCTION. Chemical equilibrium is recognized as a topic of several misconceptions. Its origins must be tracked from previous scholarship. Its impact on biochemistry learning is not fully described. A possible bulk of data is the FUVEST exam. OBJECTIVES: Identify students’ errors profile on chemical equilibrium tasks using public data from FUVEST exam. MATERIAL AND METHODS: Data analysis from FUVEST were: i Private and Public school distribution in Elementary and Middle School, and High School candidates of Pharmacy-Biochemistry course and total USP careers until the last call for enrollment (2004-2013; ii Average performance in 1st and 2nd parts of FUVEST exam of Pharmacy-Biochemistry, Chemistry, Engineering, Biological Sciences, Languages and Medicine courses and total enrolled candidates until 1st call for enrollment (2008- 2013; iii Performance of candidates of Pharmacy-Biochemistry, Chemistry, Engineering, Biological Sciences, Languages and Medicine courses and total USP careers in chemical equilibrium issues from 1st part of FUVEST (2011-2013. RESULTS AND DISCUSSION: i 66.2% of candidates came from private Elementary-Middle School courses and 71.8%, came from High School courses; ii Average grade over the period for 1st and 2nd FUVEST parts are respectively (in 100 points: Pharmacy-Biochemistry 66.7 and 61.2, Chemistry 65.9 and 58.9, Engineering 75.9 and 71.9, Biological Sciences 65.6 and 54.6, Languages 49.9 and 43.3, Medicine 83.5 and 79.5, total enrolled candidates 51,5 and 48.9; iii Four chemical equilibrium issues were found during 2011-2013 and the analysis of multiplechoice percentage distribution over the courses showed that there was a similar performance of students among them, except for Engineering and Medicine with higher grades, but the same proportional distribution among choices. CONCLUSION: Approved students came majorly from private schools. There was a different average performance among courses and similar on

  17. Estimation of FPs solubility in glass melt states by method of multi-phase chemical equilibrium calculation

    International Nuclear Information System (INIS)

    In order to study the segregation or phase-separation of fission products in alkaline borosilicate glasses, the experiments for MoO3 and RuO2 have been done. In this paper, the primary theoretical approach to the inhomogeneity has been attempted, based on multi-phase equilibrium theory

  18. Equilibrium sampling of environmental pollutants in fish: Comparison with lipid- normalized concentrations and homogenization effects on chemical activity

    DEFF Research Database (Denmark)

    Jahnke, Annika; Mayer, Philipp; Adolfsson-Erici, Margaretha;

    2011-01-01

    Equilibrium sampling of organic pollutants into the silicone polydimethylsiloxane (PDMS) has recently been applied in biological tissues including fish. Pollutant concentrations in PDMS can then be multiplied with lipid/PDMS distribution coefficients (DLipid,PDMS) to obtain concentrations in fish...

  19. An approximate method for solving the problem of the establishment of chemical equilibrium in the products of explosion of gas mixture

    Science.gov (United States)

    Shargatov, V. A.; Gubin, S. A.; Okunev, D. Yu

    2015-11-01

    Based on the assumption of the existence of the partial chemical equilibrium in the detonation products, an approximate method for calculating composition of the detonation products is developed. The method uses the assumption of the existence of extremum of Helmholtz free energy for a given density, temperature, and molecular weight of the detonation products mixture. Without significant loss of accuracy to the solution of stiff differential equations, detailed kinetic mechanism can be replaced by one differential equation and a system of algebraic equations. This method is always consistent with the detailed mechanism and can be used separately or in conjunction with the decision of a stiff system, replacing it when bimolecular reactions are near equilibrium.

  20. Ontogenetic allometry, heterochrony, and interspecific differences in the skull of African apes, using tridimensional Procrustes analysis.

    Science.gov (United States)

    Berge, Christine; Penin, Xavier

    2004-06-01

    Ontogenetic studies of African ape skulls lead to an analysis of morphological differences in terms of allometry, heterochrony, and sexual dimorphism. The use of geometric morphometrics allows us 1) to define size and shape variations as independent factors (an essential but seldom respected condition for heterochrony), and 2) to calculate in percentage of shape changes and to graphically represent the parts of shape variation which are related to various biological phenomena: common allometry, intraspecific allometry, and allometric and nonallometric shape discrimination. Three tridimensional Procrustes analyses and the calculation of multivariate allometries, discriminant functions, and statistical tests are used to compare the skulls of 50 Pan troglodytes, and 50 Gorilla gorilla of different dental stages. The results both complement and modify classical results obtained from similar material but with different methods. Size and Scaling in Primate Morphology, New York: Plenum, p. 175-205). As previously described by Shea, the common growth allometric pattern is very important (64% of total shape variation). It corresponds to a larger increase of facial volume than of neurocranial volume, a more obliquely oriented foramen magnum, and a noticeable reshaping of the nuchal region (higher inion). However, the heterochronic interpretation based on common allometry is rather different from Shea. Gorillas differ from chimpanzees not only with a larger magnitude of allometric change (rate peramorphosis), as is classically said, but also grow more in size than in shape (size acceleration). In other words, for a similar stage of growth, gorillas have the size and shape corresponding to older chimpanzees, and for a similar shape, gorillas have a larger size than chimpanzees. In contrast, sexual dimorphism actually corresponds to allometric changes only, as classically demonstrated (time hypermorphosis). Sexual dimorphism is here significant in adult gorillas alone, and

  1. Computational non-chemically equilibrium model on the current zero simulation in a model N2 circuit breaker under the free recovery condition

    International Nuclear Information System (INIS)

    A non-chemically equilibrium (non-CE) model was established to investigate the N2 arc plasma in the decaying phase during the arc interruption, and was validated by comparison with the experimental results based on laser Thomson scattering. Unlike the conventional model assuming the local thermodynamic equilibrium (LTE), in this non-CE model, the magneto-hydro-dynamics (MHD) method was coupled with the reaction kinetics to obtain the time-dependent species compositions and properties. The current calculation took into account five species in hot gas and 22 chemical reactions in total. The time-dependent species compositions of hot N2 were derived from the mass conservation equation for each species, considering the effect of the convection, diffusion and the chemical reaction. The influence of the non-CE compositions on the arc decaying behavior was realized by updating the thermodynamic and transport properties at each iterative step. The results indicate that the non-CE model can result in the departure of the arc decaying behavior from the LTE model, because it alters the time evolution of the species composition and consequently changes the thermodynamic and transport properties. At the edge of the arc, the time evolutions of the species are dominant by both the diffusion and the chemical reactions while at the center of the arc they are mainly influenced by the chemical reactions. Generally, the non-CE effect can lead to the delay of all the particles’ variations, particularly the electron decay, so that the arc interruption performance will be reduced compared with that in the LTE model. (paper)

  2. Computational non-chemically equilibrium model on the current zero simulation in a model N2 circuit breaker under the free recovery condition

    Science.gov (United States)

    Sun, Hao; Tanaka, Yasunori; Tomita, Kentaro; Wu, Yi; Rong, Mingzhe; Uesugi, Yoshihiko; Ishijima, Tatsuo

    2016-02-01

    A non-chemically equilibrium (non-CE) model was established to investigate the N2 arc plasma in the decaying phase during the arc interruption, and was validated by comparison with the experimental results based on laser Thomson scattering. Unlike the conventional model assuming the local thermodynamic equilibrium (LTE), in this non-CE model, the magneto-hydro-dynamics (MHD) method was coupled with the reaction kinetics to obtain the time-dependent species compositions and properties. The current calculation took into account five species in hot gas and 22 chemical reactions in total. The time-dependent species compositions of hot N2 were derived from the mass conservation equation for each species, considering the effect of the convection, diffusion and the chemical reaction. The influence of the non-CE compositions on the arc decaying behavior was realized by updating the thermodynamic and transport properties at each iterative step. The results indicate that the non-CE model can result in the departure of the arc decaying behavior from the LTE model, because it alters the time evolution of the species composition and consequently changes the thermodynamic and transport properties. At the edge of the arc, the time evolutions of the species are dominant by both the diffusion and the chemical reactions while at the center of the arc they are mainly influenced by the chemical reactions. Generally, the non-CE effect can lead to the delay of all the particles’ variations, particularly the electron decay, so that the arc interruption performance will be reduced compared with that in the LTE model.

  3. GENERAL EQUILIBRIUM

    Directory of Open Access Journals (Sweden)

    Monique Florenzano

    2008-09-01

    Full Text Available General equilibrium is a central concept of economic theory. Unlike partial equilibrium analysis which study the equilibrium of a particular market under the clause “ceteris paribus” that revenues and prices on the other markets stay approximately unaffected, the ambition of a general equilibrium model is to analyze the simultaneous equilibrium in all markets of a competitive economy. Definition of the abstract model, some of its basic results and insights are presented. The important issues of uniqueness and local uniqueness of equilibrium are sketched; they are the condition for a predictive power of the theory and its ability to allow for statics comparisons. Finally, we review the main extensions of the general equilibrium model. Besides the natural extensions to infinitely many commodities and to a continuum of agents, some examples show how economic theory can accommodate the main ideas in order to study some contexts which were not thought of by the initial model

  4. Passive dosing of polycyclic aromatic hydrocarbon (PAH) mixtures to terrestrial springtails: Linking mixture toxicity to chemical activities, equilibrium lipid concentrations, and toxic units

    DEFF Research Database (Denmark)

    Schmidt, Stine Nørgaard; Holmstrup, Martin; Smith, Kilian E. C.; Mayer, Philipp

    2013-01-01

    treatments, containing the polycyclic aromatic hydrocarbons (PAHs) naphthalene, phenanthrene, and pyrene. Springtail lethality was then linked to sum chemical activities (∑a), sum equilibrium lipid concentrations (∑Clipid eq.), and sum toxic units (∑TU). In each case, the effects of all 12 mixture treatments...... could be fitted to one sigmoidal exposure-response relationship. The effective lethal chemical activity (La50) of 0.027 was well within the expected range for baseline toxicity of 0.01-0.1. Linking the effects to the lipid-based exposure parameter yielded an effective lethal concentration (LClipid eq....... 50) of 133 mmol kg-1 lipid in good correspondence with the lethal membrane burden for baseline toxicity (40-160 mmol kg-1 lipid). Finally, the effective lethal toxic unit (LTU50) of 1.20 was rather close to the expected value of 1. Altogether, passive dosing provided tightly controlled mixture...

  5. Empirical analysis on the connection between power-law distributions and allometries for urban indicators

    CERN Document Server

    Alves, Luiz G A; Lenzi, Ervin K; Mendes, Renio S

    2014-01-01

    We report on the existing connection between power-law distributions and allometries. As it was first reported in [PLoS ONE 7, e40393 (2012)] for the relationship between homicides and population, when these urban indicators present asymptotic power-law distributions, they can also display specific allometries among themselves. Here, we present an extensive characterization of this connection when considering all possible pairs of relationships from twelve urban indicators of Brazilian cities (such as child labour, illiteracy, income, sanitation and unemployment). Our analysis reveal that all our urban indicators are asymptotically distributed as power laws and that the proposed connection also holds for our data when the allometric relationship displays enough correlations. We have also found that not all allometric relationships are independent and that they can be understood as a consequence of the allometric relationship between the urban indicator and the population size. We further show that the residua...

  6. Does allometry account for shape variability in Ephedrus persicae Froggatt (Hymenoptera: Braconidae: Aphidiinae) parasitic wasps?

    Czech Academy of Sciences Publication Activity Database

    Žikić, V.; Tomanović, Ž.; Kavallieratos, N. G.; Starý, Petr; Ivanović, A.

    2010-01-01

    Roč. 10, č. 5 (2010), s. 373-380. ISSN 1439-6092 R&D Projects: GA AV ČR IBS5007102 Grant ostatní: The Ministry of Science and Technological Development of the Republic of Serbia(SR) 143006B Institutional research plan: CEZ:AV0Z50070508 Keywords : allometry * morphometric variability * geometric morphometrics Subject RIV: EA - Cell Biology Impact factor: 1.581, year: 2010

  7. Maximin equilibrium

    OpenAIRE

    Ismail M.S

    2014-01-01

    We introduce a new concept which extends von Neumann and Morgensterns maximin strategy solution by incorporating individual rationality of the players. Maximin equilibrium, extending Nashs value approach, is based on the evaluation of the strategic uncertainty of the whole game. We show that maximin equilibrium is invariant under strictly increasing transformations of the payoffs. Notably, every finite game possesses a maximin equilibrium in pure strategies. Considering the games in von Neuma...

  8. Unusual allometry for sexual size dimorphism in a cichlid where males are extremely larger than females

    Indian Academy of Sciences (India)

    Kazutaka Ota; Masanori Kohda; Tetsu Sato

    2010-06-01

    When males are the larger sex, a positive allometric relationship between male and female sizes is often found across populations of a single species (i.e. Rensch’s rule). This pattern is typically explained by a sexual selection pressure on males. Here, we report that the allometric relationship was negative across populations of a shell-brooding cichlid fish Lamprologus callipterus, although males are extremely larger than females. Male L. callipterus collect and defend empty snail shells in each of which a female breeds. We found that, across six populations, male and female sizes are positively correlated with not only sexual and fecundity selection indices, but also with shell sizes. Given their different reproductive behaviours, these correlations mean that males are required to be more powerful, and thus larger, to transport larger shells, while female bodies are reduced to the shell size to enable them to enter the shells. Among the three size selections (sexual selection, fecundity selection and shell size), shell size explained the allometry, suggesting that females are more strongly subject to size selection associated with shell size availability than males. However, the allometry was violated when considering an additional population where size-selection regimes of males differed from that of other populations. Therefore, sexual size allometry will be violated by body size divergence induced by multiple selection regimes.

  9. Empirical analysis on the connection between power-law distributions and allometries for urban indicators

    Science.gov (United States)

    Alves, L. G. A.; Ribeiro, H. V.; Lenzi, E. K.; Mendes, R. S.

    2014-09-01

    We report on the existing connection between power-law distributions and allometries. As it was first reported in Gomez-Lievano et al. (2012) for the relationship between homicides and population, when these urban indicators present asymptotic power-law distributions, they can also display specific allometries among themselves. Here, we present an extensive characterization of this connection when considering all possible pairs of relationships from twelve urban indicators of Brazilian cities (such as child labor, illiteracy, income, sanitation and unemployment). Our analysis reveals that all our urban indicators are asymptotically distributed as power laws and that the proposed connection also holds for our data when the allometric relationship displays enough correlations. We have also found that not all allometric relationships are independent and that they can be understood as a consequence of the allometric relationship between the urban indicator and the population size. We further show that the residuals fluctuations surrounding the allometries are characterized by an almost constant variance and log-normal distributions.

  10. Equilibrium statistical mechanics

    CERN Document Server

    Mayer, J E

    1968-01-01

    The International Encyclopedia of Physical Chemistry and Chemical Physics, Volume 1: Equilibrium Statistical Mechanics covers the fundamental principles and the development of theoretical aspects of equilibrium statistical mechanics. Statistical mechanical is the study of the connection between the macroscopic behavior of bulk matter and the microscopic properties of its constituent atoms and molecules. This book contains eight chapters, and begins with a presentation of the master equation used for the calculation of the fundamental thermodynamic functions. The succeeding chapters highlight t

  11. Partition Equilibrium

    Science.gov (United States)

    Feldman, Michal; Tennenholtz, Moshe

    We introduce partition equilibrium and study its existence in resource selection games (RSG). In partition equilibrium the agents are partitioned into coalitions, and only deviations by the prescribed coalitions are considered. This is in difference to the classical concept of strong equilibrium according to which any subset of the agents may deviate. In resource selection games, each agent selects a resource from a set of resources, and its payoff is an increasing (or non-decreasing) function of the number of agents selecting its resource. While it has been shown that strong equilibrium exists in resource selection games, these games do not possess super-strong equilibrium, in which a fruitful deviation benefits at least one deviator without hurting any other deviator, even in the case of two identical resources with increasing cost functions. Similarly, strong equilibrium does not exist for that restricted two identical resources setting when the game is played repeatedly. We prove that for any given partition there exists a super-strong equilibrium for resource selection games of identical resources with increasing cost functions; we also show similar existence results for a variety of other classes of resource selection games. For the case of repeated games we identify partitions that guarantee the existence of strong equilibrium. Together, our work introduces a natural concept, which turns out to lead to positive and applicable results in one of the basic domains studied in the literature.

  12. ADSORPTION CHARACTERIZATION OF CO(II) IONS ONTO CHEMICALLY TREATED QUERCUS COCCIFERA SHELL: EQUILIBRIUM, KINETIC AND THERMODYNAMIC STUDIES

    OpenAIRE

    M. Hamdi Karaoglu; Mehmet Uğurlu; İbrahim Kula

    2011-01-01

    Quercus coccifera shell (QCS), a relatively abundant and inexpensive material, is currently being investigated as an adsorbent to remove cobalt(II) from water. Before the adsorption experiments, QCS was subjected to chemical treatment to provide maximum surface area. Then, the kinetics and adsorption mechanism of Co(II) ions on QCS were studied using different parameters such as adsorbent dosage, initial concentration, temperature, contact time, and solution pH. The loaded metals could be des...

  13. Physico-chemical investigation of cement carbonation in aqueous solution in equilibrium with calcite and with a controlled CO2 partial pressure at 25 and 50 deg. C

    International Nuclear Information System (INIS)

    In the framework of radioactive waste geological disposal, structural concretes have to be adapted to underground chemical conditions. For concrete in water saturated medium, it is believed that carbonation will have a major impact on the interaction between concrete and the geological medium. So, to understand the complex degradation of the cement paste in that context, it is interesting to study a simplified system such as degradation in carbonated water solution. This solution must be at equilibrium with a CO2 partial pressure 30 times higher than the atmospheric pCO2, to reproduce underground natural conditions of Callovo-Oxfordian clayey rock of Bure (France). In this study, the behaviour of a new low pH material (CEM I + silica fume + fly ashes) is compared with a CEM I cement paste, both of them being submitted to carbonation in aqueous solution in equilibrium with calcite and with a pCO2 equal to 1.32 kPa (1.3 10-2 atm). Two different temperatures, 25 and 50 C, are considered. To realize these experiments, two different original types of devices were developed

  14. Helical equilibrium

    International Nuclear Information System (INIS)

    A straight, helical plasma equilibrium equation is solved numerically for a plasma with a helical magnetic axis. As is expected, by a suitable choice of the plasma boundary, the vacuum configuration is made line ∫ dl/B stable. As the plasma pressure increases, the line ∫ dl/B criterion will improve (again as expected). There is apparently no limit on the plasma β from the equilibrium consideration. Thus helical-axis stellarator β will presumably be limited by MHD stability β, and not by equilibrium β

  15. Using the chemical equilibrium partitioning space to explore factors influencing the phase distribution of compounds involved in secondary organic aerosol formation

    Directory of Open Access Journals (Sweden)

    F. Wania

    2014-10-01

    Full Text Available Many atmospheric and chemical variables influence the partitioning equilibrium between gas phase and condensed phases of compounds implicated in the formation of secondary organic aerosol (SOA. The large number of factors and their interaction makes it often difficult to assess their relative importance and concerted impact. Here we introduce a two-dimensional space, which maps regions of dominant atmospheric phase distribution within a coordinate system defined by equilibrium partitioning coefficients between the gas phase, an aqueous phase and a water insoluble organic matter (WIOM phase. Placing compounds formed from the oxidation of n-alkanes, terpenes and mono-aromatic hydrocarbons on the maps based on their predicted partitioning properties allows for a simple graphical assessment of their equilibrium phase distribution behaviour. Specifically, it allows for the simultaneous visualization and quantitative comparison of the impact on phase distribution of changes in atmospheric parameters (such as temperature, salinity, WIOM phase polarity, organic aerosol load, and liquid water content, and chemical properties (such as oxidation state, molecular size, functionalization, and dimerisation. The graphical analysis reveals that the addition of hydroxyl, carbonyl and carboxyl groups increases the affinity of aliphatic, alicyclic and aromatic hydrocarbons for the aqueous phase more rapidly than their affinity for WIOM, suggesting that the aqueous phase may often be relevant even for substances that are considerably larger than the C2 and C3 compounds that are typically believed to be associated with aqueous SOA. In particular, the maps identify some compounds that contribute to SOA formation if partitioning to both WIOM and aqueous phase is considered, but would remain in the gas phase if either condensed phase were neglected. For example, many semi-volatile α-pinene oxidation products will contribute to aqueous SOA under the high liquid water

  16. The development of flux-split algorithms for flows with non-equilibrium thermodynamics and chemical reactions

    Science.gov (United States)

    Grossman, B.; Cinella, P.

    1988-01-01

    A finite-volume method for the numerical computation of flows with nonequilibrium thermodynamics and chemistry is presented. A thermodynamic model is described which simplifies the coupling between the chemistry and thermodynamics and also results in the retention of the homogeneity property of the Euler equations (including all the species continuity and vibrational energy conservation equations). Flux-splitting procedures are developed for the fully coupled equations involving fluid dynamics, chemical production and thermodynamic relaxation processes. New forms of flux-vector split and flux-difference split algorithms are embodied in a fully coupled, implicit, large-block structure, including all the species conservation and energy production equations. Several numerical examples are presented, including high-temperature shock tube and nozzle flows. The methodology is compared to other existing techniques, including spectral and central-differenced procedures, and favorable comparisons are shown regarding accuracy, shock-capturing and convergence rates.

  17. Uptake of gaseous formaldehyde by soil surfaces: a combination of adsorption/desorption equilibrium and chemical reactions

    Science.gov (United States)

    Li, Guo; Su, Hang; Li, Xin; Kuhn, Uwe; Meusel, Hannah; Hoffmann, Thorsten; Ammann, Markus; Pöschl, Ulrich; Shao, Min; Cheng, Yafang

    2016-08-01

    Gaseous formaldehyde (HCHO) is an important precursor of OH radicals and a key intermediate molecule in the oxidation of atmospheric volatile organic compounds (VOCs). Budget analyses reveal large discrepancies between modeled and observed HCHO concentrations in the atmosphere. Here, we investigate the interactions of gaseous HCHO with soil surfaces through coated-wall flow tube experiments applying atmospherically relevant HCHO concentrations of ˜ 10 to 40 ppbv. For the determination of uptake coefficients (γ), we provide a Matlab code to account for the diffusion correction under laminar flow conditions. Under dry conditions (relative humidity = 0 %), an initial γ of (1.1 ± 0.05) × 10-4 is determined, which gradually drops to (5.5 ± 0.4) × 10-5 after 8 h experiments. Experiments under wet conditions show a smaller γ that drops faster over time until reaching a plateau. The drop of γ with increasing relative humidity as well as the drop over time can be explained by the adsorption theory in which high surface coverage leads to a reduced uptake rate. The fact that γ stabilizes at a non-zero plateau suggests the involvement of irreversible chemical reactions. Further back-flushing experiments show that two-thirds of the adsorbed HCHO can be re-emitted into the gas phase while the residual is retained by the soil. This partial reversibility confirms that HCHO uptake by soil is a complex process involving both adsorption/desorption and chemical reactions which must be considered in trace gas exchange (emission or deposition) at the atmosphere-soil interface. Our results suggest that soil and soil-derived airborne particles can either act as a source or a sink for HCHO, depending on ambient conditions and HCHO concentrations.

  18. Caudal fin allometry in the white shark Carcharodon carcharias: implications for locomotory performance and ecology

    Science.gov (United States)

    Lingham-Soliar, Theagarten

    2005-05-01

    Allometric scaling analysis was employed to investigate the consequences of size evolution on hydrodynamic performance and ecology in the white shark Carcharodon carcharias. Discriminant analysis using the power equation y=axb was negative for caudal fin span (S) versus fork length (FL) in C. carcharias. In contrast in two delphinid species, Delphinus capensis and Tursiops aduncus, the span of the flukes versus fork length rises in positive allometric fashion, and strong positive allometry of S versus √A (area) was also recorded. The latter reflects a high lift/drag ratio. S versus √A in C. carcharias displays negative allometry and consequently a lower lift/drag ratio. A lower aspect ratio (AR) caudal fin in C. carcharias compared to that of the delphinids (mean 3.33 and 4.1, respectively) and other thunniform swimmers provides the potential for better maneuverability and acceleration. The liver in sharks is frequently associated with a buoyancy function and was found to be positively allometric in C. carcharias. The overall findings suggest that the negatively allometric caudal fin morphometrics in C. carcharias are unlikely to have deleterious evolutionary fitness consequences for predation. On the contrary, when considered in the context of positive liver allometry in C. carcharias it is hereby suggested that buoyancy may play a dominant role in larger white sharks in permitting slow swimming while minimizing energy demands needed to prevent sinking. In contrast hydrodynamic lift is considered more important in smaller white sharks. Larger caudal fin spans and higher lift/drag ratio in smaller C. carcharias indicate greater potential for prolonged, intermediate swimming speeds and for feeding predominantly on fast-moving fish, in contrast to slow-swimming search patterns of larger individuals for predominantly large mammalian prey. Such data may provide some answers to the lifestyle and widespread habitat capabilities of this still largely mysterious animal.

  19. Stepwise substitution of Μ3-Te ligands in octahedral cluster core (Re6Te8)2+: NMR spectroscopic evidence of equilibrium between chemical forms

    International Nuclear Information System (INIS)

    High-temperature reactions of the (Re6Te8)Te7 rhenium telluride with elementary sulfur and selenium, leading to formation of substitution solid solutions of the (Re6Te8-xYx)Te7 type, where by Y=S, Se,; 0≤x≤8, are studied. Complex salts of the K4(Re6Te8-xYx)(CN)6 compositions, preserving the cluster nucleus of the source compounds, are synthesized through interaction of the (Re6Te8-xYx)Te7 solid phases with the KCN melt. The salts water solutions are studied through the NMR spectroscopy method on 77Se and 125Te nuclei. Complex spectra for various composition samples are obtained. The additive model applied adequately describes the NMP spectra for all studied samples. The conclusion is made on the basis of the data obtained that the (Re6Te8-xYx)Te7 phases with certain x-values contain practically the set of different chemical forms (with different values), whereby quantitative ratios between them are determined by corresponding equilibrium constants

  20. A Lakatosian Conceptual Change Teaching Strategy Based on Student Ability to Build Models with Varying Degrees of Conceptual Understanding of Chemical Equilibrium

    Science.gov (United States)

    Niaz, M.

    The main objective of this study is to construct a Lakatosian teaching strategy that can facilitate conceptual change in students'' understanding of chemical equilibrium. The strategy is based on the premise that cognitive conflicts must have been engendered by the students themselves in trying to cope with different problem solving strategies. Results obtained (based on Venezuelan freshman students) show that the performance of the experimental group of students was generally better (especially on the immediate post tests) than that of the control group. It is concluded that a conceptual change teaching strategy must take into consideration the following aspects: a) core beliefs of the students in the topic (cf. ''hard core'', Lakatos 1970); b) exploration of the relationship between core beliefs and student alternative conceptions (misconceptions); c) cognitive complexity of the core belief can be broken down into a series of related and probing questions; d) students resist changes in their core beliefs by postulating ''auxiliary hypotheses'' in order to resolve their contradictions; e) students'' responses based on their alternative conceptions must be considered not as wrong, but rather as models, perhaps in the same sense as used by scientists to break the complexity of a problem; and f) students'' misconceptions be considered as alternative conceptions (theories) that compete with the present scientific theories and at times recapitulate theories scientists held in the past.

  1. Effect of the relative time of emergence on the growth allometry of Galium aparine in competition with Triticum aestivum

    Czech Academy of Sciences Publication Activity Database

    Klem, Karel; Rajsnerová, Petra; Novotná, Kateřina; Urban, Otmar; Marek, Michal V.

    2014-01-01

    Roč. 14, č. 4 (2014), s. 262-270. ISSN 1444-6162 R&D Projects: GA MZe QI111A133; GA TA ČR TA02010780 Institutional support: RVO:67179843 Keywords : cleaver * competition * growth allometry * relative time of emergence * wheat Subject RIV: GC - Agronomy Impact factor: 0.537, year: 2014

  2. Methanol synthesis beyond chemical equilibrium

    NARCIS (Netherlands)

    van Bennekom, J. G.; Venderbosch, R. H.; Winkelman, J. G. M.; Wilbers, E.; Assink, D.; Lemmens, K. P. J.; Heeres, H. J.

    2013-01-01

    In commercial methanol production from syngas, the conversion is thermodynamically limited to 0.3-0.7 leading to large recycles of non-converted syngas. This problem can be overcome to a significant extent by in situ condensation of methanol during its synthesis which is possible nowadays due to the

  3. Sweatshop equilibrium

    OpenAIRE

    Chau, Nancy H.

    2009-01-01

    This paper presents a capability-augmented model of on the job search, in which sweatshop conditions stifle the capability of the working poor to search for a job while on the job. The augmented setting unveils a sweatshop equilibrium in an otherwise archetypal Burdett-Mortensen economy, and reconciles a number of oft noted yet perplexing features of sweatshop economies. We demonstrate existence of multiple rational expectation equilibria, graduation pathways out of sweatshops in complete abs...

  4. Kinetics and equilibrium studies on biosorption of cadmium, lead, and nickel ions from aqueous solutions by intact and chemically modified brown algae

    International Nuclear Information System (INIS)

    Research highlights: → The present study deals with the evaluation of biosorptive removal of Cd (II), Ni (II) and Pb (II) ions by both intact and pre-treated brown marine algae: Cystoseira indica, Sargassum glaucescens, Nizimuddinia zanardini and Padina australis treated with formaldehyde (FA), glutaraldehyde (GA), polyethylene imine (PEI), calcium chloride (CaCl2) and hydrochloric acid (HCl). From the results obtained, chemically modification leads to higher capacity of biosorption. → The equilibrium experimental data were tested using the most common isotherms. The results are best fitted by the Freundlich model among two-parameter models and the Toth, Khan and Radke-Prausnitz models among three-parameter isotherm models for Cd (II), Ni (II) and Pb (II), respectively. → One-way ANOVA and one sample t-tests were performed on experimental data to evaluate the statistical significance of biosorption capacities after five cycles of sorption and desorption. → The kinetic data were fitted by models including pseudo-first-order and pseudo-second-order. From the results obtained, the pseudo-second-order kinetic model describes best the biosorption of cadmium, nickel and lead ions. - Abstract: The present study deals with the evaluation of biosorptive removal of Cd (II), Ni (II) and Pb (II) ions by both intact and pre-treated brown marine algae: Cystoseira indica, Sargassum glaucescens, Nizimuddinia zanardini and Padina australis treated with formaldehyde (FA), glutaraldehyde (GA), polyethylene imine (PEI), calcium chloride (CaCl2) and hydrochloric acid (HCl). Batch shaking adsorption experiments were performed in order to examine the effects of pH, contact time, biomass concentration, biomass treatment and initial metal concentration on the removal process. The optimum sorption conditions for each heavy metal are presented. One-way ANOVA and one sample t-tests were performed on experimental data to evaluate the statistical significance of biosorption capacities

  5. Kinetics and equilibrium studies on biosorption of cadmium, lead, and nickel ions from aqueous solutions by intact and chemically modified brown algae

    Energy Technology Data Exchange (ETDEWEB)

    Montazer-Rahmati, Mohammad Mehdi, E-mail: mrahmati@ut.ac.ir [School of Chemical Engineering, College of Engineering, University of Tehran, P.O. Box: 11155-4563, Tehran 4563 (Iran, Islamic Republic of); Rabbani, Parisa; Abdolali, Atefeh [School of Chemical Engineering, College of Engineering, University of Tehran, P.O. Box: 11155-4563, Tehran 4563 (Iran, Islamic Republic of); Keshtkar, Ali Reza [Nuclear Science and Technology Research Institute, Atomic Energy Organization of Iran, P.O. Box: 11365-8486, Tehran (Iran, Islamic Republic of)

    2011-01-15

    Research highlights: {yields} The present study deals with the evaluation of biosorptive removal of Cd (II), Ni (II) and Pb (II) ions by both intact and pre-treated brown marine algae: Cystoseira indica, Sargassum glaucescens, Nizimuddinia zanardini and Padina australis treated with formaldehyde (FA), glutaraldehyde (GA), polyethylene imine (PEI), calcium chloride (CaCl{sub 2}) and hydrochloric acid (HCl). From the results obtained, chemically modification leads to higher capacity of biosorption. {yields} The equilibrium experimental data were tested using the most common isotherms. The results are best fitted by the Freundlich model among two-parameter models and the Toth, Khan and Radke-Prausnitz models among three-parameter isotherm models for Cd (II), Ni (II) and Pb (II), respectively. {yields} One-way ANOVA and one sample t-tests were performed on experimental data to evaluate the statistical significance of biosorption capacities after five cycles of sorption and desorption. {yields} The kinetic data were fitted by models including pseudo-first-order and pseudo-second-order. From the results obtained, the pseudo-second-order kinetic model describes best the biosorption of cadmium, nickel and lead ions. - Abstract: The present study deals with the evaluation of biosorptive removal of Cd (II), Ni (II) and Pb (II) ions by both intact and pre-treated brown marine algae: Cystoseira indica, Sargassum glaucescens, Nizimuddinia zanardini and Padina australis treated with formaldehyde (FA), glutaraldehyde (GA), polyethylene imine (PEI), calcium chloride (CaCl{sub 2}) and hydrochloric acid (HCl). Batch shaking adsorption experiments were performed in order to examine the effects of pH, contact time, biomass concentration, biomass treatment and initial metal concentration on the removal process. The optimum sorption conditions for each heavy metal are presented. One-way ANOVA and one sample t-tests were performed on experimental data to evaluate the statistical

  6. Temporal assessment of copper speciation, bioavailability and toxicity in UK freshwaters using chemical equilibrium and biotic ligand models: Implications for compliance with copper environmental quality standards.

    Science.gov (United States)

    Lathouri, Maria; Korre, Anna

    2015-12-15

    Although significant progress has been made in understanding how environmental factors modify the speciation, bioavailability and toxicity of metals such as copper in aquatic environments, the current methods used to establish water quality standards do not necessarily consider the different geological and geochemical characteristics of a given site and the factors that affect copper fate, bioavailability potential and toxicity. In addition, the temporal variation in the concentration and bioavailable metal fraction is also important in freshwater systems. The work presented in this paper illustrates the temporal and seasonal variability of a range of water quality parameters, and Cu speciation, bioavailability and toxicity at four freshwaters sites in the UK. Rivers Coquet, Cree, Lower Clyde and Eden (Kent) were selected to cover a broad range of different geochemical environments and site characteristics. The monitoring data used covered a period of around six years at almost monthly intervals. Chemical equilibrium modelling was used to study temporal variations in Cu speciation and was combined with acute toxicity modelling to assess Cu bioavailability for two aquatic species, Daphnia magna and Daphnia pulex. The estimated copper bioavailability, toxicity levels and the corresponding ecosystem risks were analysed in relation to key water quality parameters (alkalinity, pH and DOC). Although copper concentrations did not vary much during the sampling period or between the seasons at the different sites; copper bioavailability varied markedly. In addition, through the chronic-Cu BLM-based on the voluntary risk assessment approach, the potential environmental risk in terms of the chronic toxicity was assessed. A much higher likelihood of toxicity effects was found during the cold period at all sites. It is suggested that besides the metal (copper) concentration in the surface water environment, the variability and seasonality of other important water quality

  7. Extreme positive allometry of animal adhesive pads and the size limits of adhesion-based climbing.

    Science.gov (United States)

    Labonte, David; Clemente, Christofer J; Dittrich, Alex; Kuo, Chi-Yun; Crosby, Alfred J; Irschick, Duncan J; Federle, Walter

    2016-02-01

    Organismal functions are size-dependent whenever body surfaces supply body volumes. Larger organisms can develop strongly folded internal surfaces for enhanced diffusion, but in many cases areas cannot be folded so that their enlargement is constrained by anatomy, presenting a problem for larger animals. Here, we study the allometry of adhesive pad area in 225 climbing animal species, covering more than seven orders of magnitude in weight. Across all taxa, adhesive pad area showed extreme positive allometry and scaled with weight, implying a 200-fold increase of relative pad area from mites to geckos. However, allometric scaling coefficients for pad area systematically decreased with taxonomic level and were close to isometry when evolutionary history was accounted for, indicating that the substantial anatomical changes required to achieve this increase in relative pad area are limited by phylogenetic constraints. Using a comparative phylogenetic approach, we found that the departure from isometry is almost exclusively caused by large differences in size-corrected pad area between arthropods and vertebrates. To mitigate the expected decrease of weight-specific adhesion within closely related taxa where pad area scaled close to isometry, data for several taxa suggest that the pads' adhesive strength increased for larger animals. The combination of adjustments in relative pad area for distantly related taxa and changes in adhesive strength for closely related groups helps explain how climbing with adhesive pads has evolved in animals varying over seven orders of magnitude in body weight. Our results illustrate the size limits of adhesion-based climbing, with profound implications for large-scale bio-inspired adhesives. PMID:26787862

  8. Allometry of animal–microbe interactions and global census of animal-associated microbes

    Science.gov (United States)

    Kieft, Thomas L.; Simmons, Karen A.

    2015-01-01

    Animals live in close association with microorganisms, mostly prokaryotes, living in or on them as commensals, mutualists or parasites, and profoundly affecting host fitness. Most animal–microbe studies focus on microbial community structure; for this project, allometry (scaling of animal attributes with animal size) was applied to animal–microbe relationships across a range of species spanning 12 orders of magnitude in animal mass, from nematodes to whales. Microbial abundances per individual animal were gleaned from published literature and also microscopically counted in three species. Abundance of prokaryotes/individual versus animal mass scales as a nearly linear power function (exponent = 1.07, R2 = 0.94). Combining this power function with allometry of animal abundance indicates that macrofauna have an outsized share of animal-associated microorganisms. The total number of animal-associated prokaryotes in Earth's land animals was calculated to be 1.3–1.4 × 1025 cells and the total of marine animal-associated microbes was calculated to be 8.6–9.0 × 1024 cells. Animal-associated microbes thus total 2.1–2.3 × 1025 of the approximately 1030 prokaryotes on the Earth. Microbes associated with humans comprise 3.3–3.5% of Earth's animal-associated microbes, and domestic animals harbour 14–20% of all animal-associated microbes, adding a new dimension to the scale of human impact on the biosphere. This novel allometric power function may reflect underlying mechanisms involving the transfer of energy and materials between microorganisms and their animal hosts. Microbial diversity indices of animal gut communities and gut microbial species richness for 60 mammals did not indicate significant scaling relationships with animal body mass; however, further research in this area is warranted. PMID:26108631

  9. Allometry of animal-microbe interactions and global census of animal-associated microbes.

    Science.gov (United States)

    Kieft, Thomas L; Simmons, Karen A

    2015-07-01

    Animals live in close association with microorganisms, mostly prokaryotes, living in or on them as commensals, mutualists or parasites, and profoundly affecting host fitness. Most animal-microbe studies focus on microbial community structure; for this project, allometry (scaling of animal attributes with animal size) was applied to animal-microbe relationships across a range of species spanning 12 orders of magnitude in animal mass, from nematodes to whales. Microbial abundances per individual animal were gleaned from published literature and also microscopically counted in three species. Abundance of prokaryotes/individual versus animal mass scales as a nearly linear power function (exponent = 1.07, R(2) = 0.94). Combining this power function with allometry of animal abundance indicates that macrofauna have an outsized share of animal-associated microorganisms. The total number of animal-associated prokaryotes in Earth's land animals was calculated to be 1.3-1.4 × 10(25) cells and the total of marine animal-associated microbes was calculated to be 8.6-9.0 × 10(24) cells. Animal-associated microbes thus total 2.1-2.3 × 10(25) of the approximately 10(30) prokaryotes on the Earth. Microbes associated with humans comprise 3.3-3.5% of Earth's animal-associated microbes, and domestic animals harbour 14-20% of all animal-associated microbes, adding a new dimension to the scale of human impact on the biosphere. This novel allometric power function may reflect underlying mechanisms involving the transfer of energy and materials between microorganisms and their animal hosts. Microbial diversity indices of animal gut communities and gut microbial species richness for 60 mammals did not indicate significant scaling relationships with animal body mass; however, further research in this area is warranted. PMID:26108631

  10. Para-equilibrium phase diagrams

    International Nuclear Information System (INIS)

    Highlights: • A rapidly cooled system may attain a state of para-equilibrium. • In this state rapidly diffusing elements reach equilibrium but others are immobile. • Application of the Phase Rule to para-equilibrium phase diagrams is discussed. • A general algorithm to calculate para-equilibrium phase diagrams is described. - Abstract: If an initially homogeneous system at high temperature is rapidly cooled, a temporary para-equilibrium state may result in which rapidly diffusing elements have reached equilibrium but more slowly diffusing elements have remained essentially immobile. The best known example occurs when homogeneous austenite is quenched. A para-equilibrium phase assemblage may be calculated thermodynamically by Gibbs free energy minimization under the constraint that the ratios of the slowly diffusing elements are the same in all phases. Several examples of calculated para-equilibrium phase diagram sections are presented and the application of the Phase Rule is discussed. Although the rules governing the geometry of these diagrams may appear at first to be somewhat different from those for full equilibrium phase diagrams, it is shown that in fact they obey exactly the same rules with the following provision. Since the molar ratios of non-diffusing elements are the same in all phases at para-equilibrium, these ratios act, as far as the geometry of the diagram is concerned, like “potential” variables (such as T, pressure or chemical potentials) rather than like “normal” composition variables which need not be the same in all phases. A general algorithm to calculate para-equilibrium phase diagrams is presented. In the limit, if a para-equilibrium calculation is performed under the constraint that no elements diffuse, then the resultant phase diagram shows the single phase with the minimum Gibbs free energy at any point on the diagram; such calculations are of interest in physical vapor deposition when deposition is so rapid that phase

  11. Chemically treated kola nut pod as low-cost natural adsorbent for the removal of 2,4-dinitrophenol from synthetic wastewater: batch equilibrium, kinetic, and thermodynamic modelling studies

    OpenAIRE

    AGARRY, Samuel; OGUNLEYE, Oladipupo

    2014-01-01

    The feasibility of using chemically treated kola nut pod to remove 2,4-dinitrophenol from its aqueous solutions under batch mode was investigated. The results showed that biosorption of 2,4-dinitrophenol was dependent on initial concentration, contact time, pH, biosorbent particle size, biosorbent dosage, and temperature. The batch equilibrium biosorption data were analyzed by 2 two-parameter (Langmuir and Freundlich) and 2 three-parameter (Redlich--Peterson and Sips) adsorption isother...

  12. Exoplanet Equilibrium Chemistry Calculations

    Science.gov (United States)

    Blumenthal, Sarah; Harrington, J.; Bowman, M.; Blecic, J.

    2013-10-01

    Recently, Agundez et al. (2012, A&A 548, A73) used a chemical kinetics code to study a model HD 209458b (equilibrium temperature of 1450 K, assuming full redistribution and 0 albedo). They found that thermochemistry dominates most of the dayside, but that significant compositional gradients may exist across the dayside. We calculate equilibrium-chemistry molecular abundances for several model exoplanets, using NASA's open-source Chemical Equilibrium Abundances code (McBride and Gordon 1996). We vary the degree of radiation redistribution to the dark side, ranging from total redistribution to instantaneous reradiation. Atomically, both the solar abundance multiple and the carbon fraction vary. Planet substellar temperatures range from just above 1200 K, where photochemistry should no longer be important, to those of hot planets (3000 K). We present synthetic abundance images for the key spectroscopic molecules CO, CH4, and H2O for several hot-Jupiter model planets. This work was supported by the NASA Planetary Atmospheres grant NNX12AI69G.

  13. Chromatographic speciation of Cr(III)-species, inter-species equilibrium isotope fractionation and improved chemical purification strategies for high-precision isotope analysis.

    Science.gov (United States)

    Larsen, K K; Wielandt, D; Schiller, M; Bizzarro, M

    2016-04-22

    Chromatographic purification of chromium (Cr), which is required for high-precision isotope analysis, is complicated by the presence of multiple Cr-species with different effective charges in the acid digested sample aliquots. The differing ion exchange selectivity and sluggish reaction rates of these species can result in incomplete Cr recovery during chromatographic purification. Because of large mass-dependent inter-species isotope fractionation, incomplete recovery can affect the accuracy of high-precision Cr isotope analysis. Here, we demonstrate widely differing cation distribution coefficients of Cr(III)-species (Cr(3+), CrCl(2+) and CrCl2(+)) with equilibrium mass-dependent isotope fractionation spanning a range of ∼1‰/amu and consistent with theory. The heaviest isotopes partition into Cr(3+), intermediates in CrCl(2+) and the lightest in CrCl2(+)/CrCl3°. Thus, for a typical reported loss of ∼25% Cr (in the form of Cr(3+)) through chromatographic purification, this translates into 185ppm/amu offset in the stable Cr isotope ratio of the residual sample. Depending on the validity of the mass-bias correction during isotope analysis, this further results in artificial mass-independent effects in the mass-bias corrected (53)Cr/(52)Cr (μ(53)Cr* of 5.2ppm) and (54)Cr/(52)Cr (μ(54)Cr* of 13.5ppm) components used to infer chronometric and nucleosynthetic information in meteorites. To mitigate these fractionation effects, we developed strategic chemical sample pre-treatment procedures that ensure high and reproducible Cr recovery. This is achieved either through 1) effective promotion of Cr(3+) by >5 days exposure to HNO3H2O2 solutions at room temperature, resulting in >∼98% Cr recovery for most types of sample matrices tested using a cationic chromatographic retention strategy, or 2) formation of Cr(III)-Cl complexes through exposure to concentrated HCl at high temperature (>120°C) for several hours, resulting in >97.5% Cr recovery using a

  14. Foraging and vulnerability traits modify predator-prey body mass allometry: freshwater macroinvertebrates as a case study

    Czech Academy of Sciences Publication Activity Database

    Klečka, Jan; Boukal S., David

    2013-01-01

    Roč. 82, č. 5 (2013), s. 1031-1041. ISSN 0021-8790 Grant ostatní: AquaMod(CZ) PERG04-GA-2008-239543; GA JU(CZ) GAJU 145/2010/P; MŠMT(CZ) 7947/2010 30 Institutional support: RVO:60077344 Keywords : allometry * aquatic insects * Dytiscidae Subject RIV: EH - Ecology, Behaviour Impact factor: 4.726, year: 2013 http://onlinelibrary.wiley.com/doi/10.1111/1365-2656.12078/full

  15. Allometry in carcasses of lambs of the Pantaneiro genetic group slaughtered with different subcutaneous fat thickness

    Directory of Open Access Journals (Sweden)

    Natália Holtz Alves Pedroso Mora

    2014-09-01

    Full Text Available Twenty-four female lambs of the Pantaneiro genetic group, with approximately 100 days of age, average body of 16.24 ± 1.78 kg, were slaughtered with 2.0, 3.0 and 4.0 mmof subcutaneous fat thickness, measured by ultrasound in the Longissimus, to evaluate the allometric growth. Lambs fed a complete pelleted diet calculated to ensure a daily weight gain of0.30 kg. Slaughtering was performed as the female lambs reached the pre-established fat thickness. After 24 hours in a cold chamber at 4ºC, chilled carcasses were cut in half and weighed. The right side was separated into five sections to determine the allometry of carcasses and cuts. Neck and rib showed isogonic growth in all treatments. Loin has remained late growth to 2.0 and3.0 mm. Shoulder and leg were isogonic growth in the treatments 3.0 and4.0 mm. The leg in relation to half carcass showed the greatest correlation. The cuts exhibited differentiated development in the growth rates of tissues. It is recommended to slaughter female lambs when they reach3.0 mm of subcutaneous fat thickness, since the carcass has already reached physiological maturity. Shoulder and leg cuts are best suited for dissection for presenting the highest correlation with the carcass in females of the Pantaneiro group.

  16. Inter-site variation in allometry and wood density of Goupia glabra Aubl. in Amazonia.

    Science.gov (United States)

    Siliprandi, N C; Nogueira, E M; Toledo, J J; Fearnside, P M; Nascimento, H E M

    2016-02-01

    The present study aims to compare the allometry and wood density of Goupia glabra Aubl. (Goupiaceae) in two different terra-firme sites in Amazonian forest. A total of 65 trees ≥ 10 cm DBH was sampled in both sites, with 39 trees in Nova Olinda do Norte (NOlinda, near the Amazon River) and 29 trees in Apuí (near the southern edge of the Amazon forest). Except for the relationship between DBH (diameter at breast height) and Ht (total height), allometric relationships for G.glabra differed significantly between sites. Apuí had lower intercept and greater slope for log10 (DBH) versus log10 (Hs - stem height), and, conversely, greater intercept and lower slope for log10 (DBH) versus log10 (Ch - crown height). The slope differed significantly between the sites for DBH versus Cd (crown diameter), with greater slope found for NOlinda. Mean basic wood density in Apuí was 8.8% lower than in NOlinda. Our findings highlight the variation in adaptive strategy of G. glabra due to environmental differences between sites. This is probably because of different canopy-understory light gradients, which result in differentiation of resource allocation between vertical and horizontal growth, which, in turn, affects mechanical support related to wood density. We also hypothesize that differences in soil fertility and disturbance regimes between sites may act concomitantly with light. PMID:26909641

  17. Transesterification of canola, palm, peanut, soybean and sunflower oil with methanol, ethanol, isopropanol, butanol and tert-butanol to biodiesel: Modelling of chemical equilibrium, reaction kinetics and mass transfer based on fatty acid composition

    International Nuclear Information System (INIS)

    Graphical abstract: Modelling of chemical equilibrium, reaction kinetics and mass transfer for triglyceride transesterification with different alcohols based on fatty acid composition. - Highlights: • Catalysed transesterification to biodiesel with various oils, alcohols and catalysts. • Analysis of components and reactivity based on fatty acid composition of all species. • Simultaneous modelling of mass transfer, reaction kinetics and chemical equilibrium. • Diffusivities, distribution and mass transfer coefficients for individual components. • Correlation of kinetic parameters with molecular structure of reactants and products. - Abstract: Mechanism of alcoholysis (e.g. methanolysis) using different oils, alcohols and homogeneous base catalysts was utilized to devise chemical kinetics and thermodynamics based on fatty acid composition, differentiating among triglycerides, diglycerides, monoglycerides and fatty acid alkyl esters (e.g. fatty acid alkyl esters, FAME) with bonded gadoleic, linoleic, linolenic, oleic, palmitic and stearic acid-originating substituents. Their concentrations were measured using an optimized high-performance liquid chromatography (HPLC) method. Hydrodynamics and diffusion limitations in emulsion were considered in overall model by determining diffusivities, distribution coefficients, molar volumes, boiling points and viscosities of individual components. Pre-exponential factors and activation energies were related with structure of reactants, intermediates and products acknowledging number of carbons, double bonds and alkyl branches by linear and mixed response surface methodology. Developed model may be used with batch and continuous flow reactors, e.g. for novel micro-structured or industrial-scale process intensification, different vegetable or non-edible oils (waste cooking Jatropha or microalgae lipids)

  18. Robust Learning Equilibrium

    OpenAIRE

    Ashlagi, Itai; Monderer, Dov; Tennenholtz, Moshe

    2012-01-01

    We introduce robust learning equilibrium. The idea of learning equilibrium is that learning algorithms in multi-agent systems should themselves be in equilibrium rather than only lead to equilibrium. That is, learning equilibrium is immune to strategic deviations: Every agent is better off using its prescribed learning algorithm, if all other agents follow their algorithms, regardless of the unknown state of the environment. However, a learning equilibrium may not be immune to non strategic m...

  19. Neutral zinc(II) O,O-di-alkyldithiopho- sphates-variable temperature 31P NMR and quantum chemical study of the ZDDP monomer-dimer equilibrium.

    Science.gov (United States)

    Harrison, J J; Chan, C Y; Onopchenko, A; Pradhan, A R; Petersen, M

    2008-02-01

    A full line-shape analysis of the VT 31P NMR spectra was carried out for the monomer-dimer equilibrium of neutral ZDDP. The energy surface and the energetics of the monomer-dimer equilibrium (DeltaH degrees , DeltaG degrees , Ea, DeltaH(not equal), and DeltaG(not equal)) are reported for three variants wherein the alkyl groups in the ZDDP are 2-ethylhexyl, isopropyl, and isobutyl. We explored a reaction pathway between the monomer and dimer form by means of density functional theory (DFT). The linear combination of atomic orbitals (LCAO) code DMol3 was used together with a synchronous transient method to effectively locate transition states. Vibrational eigenmodes of all intermediates were computed to capture finite temperature effects. Methyl and ethyl were considered as alkyl groups. Two novel intermediates were located-a four-membered ring and a six-membered ring intermediate along the reaction coordinate. Comparison of the experimentally derived and computed energy surfaces was carried out. PMID:18098153

  20. Allometry of a neotropical palm, Euterpe edulis Mart. Alometria de uma palmeira Neotropical, Euterpe edulis Mart

    Directory of Open Access Journals (Sweden)

    Luciana F. Alves

    2004-06-01

    Full Text Available The stem allometry (stem diameter vs. tree height of a Neotropical palm (Euterpe edulis found in rain and seasonal forest of Southeastern Brazil was examined. Observed height-diameter relationships along the stem (diameter at ground level, (dgl, and diameter at breast height (dbh were compared to three theoretical stability mechanical models: elastic similarity, stress similarity and geometric similarity. Slopes of log-transformed height-diameter relationships did not lie near those predicted by any stability mechanical models. Significant differences in stem allometry were found when comparing dgl to dbh, suggesting greater increase in dbh with height. The relationship between stability safety factor (SSF and palm height showed that both dgl and dbh were found to be above McMahon's theoretical buckling limit for dicotyledonous trees, but some individuals approached this limit in relation to dbh. Despite displaying a similar decreasing pattern of SSF with height, differences found in SSF along the stem - greater SSF for dgl when compared to dbh - indicate that the risk of mechanism failure in palms depends upon the size and varies along the stem. Distinct allometric relationships along the stem obtained for Euterpe edulis may be reflecting possible differences in stem design and growth strategies.Neste trabalho foram analisadas as relações entre o diâmetro e a altura de uma palmeira Neotropical (Euterpe edulis comum na Floresta Atlântica do SE do Brasil. As relações observadas entre a altura e o diâmetro ao longo do estipe (diâmetro ao nível do solo (DAS, e diâmetro ao nível do peito (DAP foram comparadas a três modelos teóricos de estabilidade mecânica: similaridade elástica, similaridade de estresse e similaridade geométrica. As inclinações das regressões altura-diâmetro não se ajustaram a nenhum dos modelos de estabilidade mecânica. Diferenças significativas na alometria do estipe foram encontradas comparando-se as rela

  1. Long-Bone Allometry of Terrestrial Mammals and the Geometric-Shape and Elastic-Force Constraints of Bone Evolution

    CERN Document Server

    Kokshenev, V B; García, G J M

    2003-01-01

    A natural similarity in body dimensions of terrestrial animals noticed by ancient philosophers remains the main key to the problem of mammalian skeletal evolution with body mass explored in theoretical and experimental biology and tested by comparative zoologists. We discuss the long-standing problem of mammalian bone allometry commonly studied in terms of the so-called ''geometric'', ''elastic'', and ''static stress'' similarities by McMahon (1973, 1975a, 1975b). We revise the fundamental assumptions underlying these similarities and give new physical insights into geometric-shape and elastic-force constraints imposed on spatial evolution of mammalian long bones.

  2. Allometry and proximate mechanisms of sexual selection in photinus fireflies, and some other beetles.

    Science.gov (United States)

    Vencl, Fredric V

    2004-06-01

    Ever since Darwin identified it as the force responsible for the evolution of exaggerated male characters, sexual selection has been the focus of research aimed at understanding the most bizarre and intriguing morphologies and behaviors in Nature. Two congeneric species in the firefly genus Photinus, P. pyralis and P. macdermotti, afford a unique opportunity to examine the interaction between sexual and countervailing natural selection that act to shape the evolution of mating behavior and body size in closely related species with very different courtship strategies. Photinus pyralis males emit very bright flashes during their extended patrolling flights and form 'love knots' of competing suitors, while P. macdermotti males, whose courtships seldom exceed two competing males, produce weaker flashes during a shorter patrolling period.Possibly as a consequence of their scramble competition and long flights, not only is there an extremely wide range of body sizes in P. pyralis males, but they also exhibit wing allometric slopes greater than one, and lantern allometries less than one. In contrast, P. macdermotti males do not have allometric slopes significantly different from one. Small males, when tested in an artificial scramble situation move faster than large males, an advantage in the intense competition that ensues once a female is located. Females answer several males in alternation and fail to respond to all male flashes, with the evident consequence that love knots frequently develop around such fickle females. Allometric relationships in two non-luminescent beetle species with non-visual courtship protocols are compared. Visual, sexually selected characters showed positive allometric slopes, while non-visual characters showed isometry or negative slopes. Data presented here support the existence of distinct patterns in modality-specific sexual selection. PMID:21676703

  3. Influence of shade tolerance and development stage on the allometry of ten temperate tree species.

    Science.gov (United States)

    Franceschini, Tony; Schneider, Robert

    2014-11-01

    Allometry studies the change in scale between two dimensions of an organism. The metabolic theory of ecology predicts invariant allometric scaling exponents, while empirical studies evidenced inter- and intra-specific variations. This work aimed at identifying the sources of variations of the allometric exponents at both inter- and intra-specific levels using stem analysis from 9,363 trees for ten Eastern Canada species with a large shade-tolerance gradient. Specifically, the yearly allometric exponents, α(v,DBH) [volume (v) and diameter at breast height (DBH)], β(v,h) [v and height (h)], and γ(h,DBH) (h and DBH) were modelled as a function of tree age for each species. α(v,DBH), and γ(h,DBH) increased with tree age and then reached a plateau ranging from 2.45 to 3.12 for α(v,DBH), and 0.874-1.48 for γ(h,DBH). Pine species presented a local maximum. No effect of tree age on β(v,h) was found for conifers, while it increased until a plateau ranging from 3.71 to 5.16 for broadleaves. The influence of shade tolerance on the growth trajectories was then explored. In the juvenile stage, α(v,DBH), and γ(h,DBH) increased with shade tolerance while β(v,h) was shade-tolerance independent. In the mature stage, β(v,h) increased with shade tolerance, whereas γ(h,DBH) decreased and α(v,DBH) was shade-tolerance independent. The interaction between development stage and shade tolerance for allometric exponents demonstrates the importance of the changing functional requirements of trees for resource allocation at both the inter- and intra-specific level. These results indicate the need to also integrate specific functional traits, growth strategies and allocation, in allometric theoretical frameworks. PMID:25168006

  4. Dynamics of the Developing Chick Chorioallantoic Membrane Assessed by Stereology, Allometry, Immunohistochemistry and Molecular Analysis

    Science.gov (United States)

    Makanya, Andrew Ndegwa; Dimova, Ivanka; Koller, Tobias; Styp-Rekowska, Beata; Djonov, Valentin

    2016-01-01

    The chick chorioallantoic membrane (CAM) is a widely used model for the study of angiogenesis, tumour growth, as well as drug efficacy. In spite of this, little is known about the developmental alteration from its appearance to the time of hatching. In the current study the CAM has been studied by classical stereology and allometry. Expression levels of selected angiogenesis-related molecules were estimated by RT-PCR and cell dynamics assessed by proliferation and apoptosis assays. Absolute CAM volume increased from a low of 0.47 ± 0.11 cm3 at embryonic day 8 (E8) to a high of 2.05 ± 0.27 cm3 at E18, and then decreased to 1.6 ± 0.47 cm3 at E20. On allometric analysis, three growth phases were identifiable. Between E8-13 (phase I), the CAM grew fastest; moderately in phase II (E13-18) but was regressing in phase III (E18-20). The chorion, the mesenchyme and the allantoic layers grew fastest in phase I, but moderately in phase II. The mesenchyme grew slowly in phase III while the chorion and allantois were regressing. Chorionic cell volume increased fastest in phase I and was regressing in phase III. Chorionic capillaries grew steadily in phase I and II but regressed in phase III. Both the chorion and the allantois grew by intrinsic cell proliferation as well as recruitment of cells from the mesenchyme. Cell proliferation was prominent in the allantois and chorion early during development, declined after E17 and apoptosis started mainly in the chorion from E14. VEGFR2 expression peaked at E11 and declined steadily towards E20, VEGF peaked at E13 and E20 while HIF 1α had a peak at E11 and E20. Studies targeting CAM growth and angiogenesis need to take these growth phases into consideration PMID:27046154

  5. Vision in semi-aquatic snakes: Intraocular morphology, accommodation, and eye: Body allometry

    Science.gov (United States)

    Plylar, Helen Bond

    Vision in vertebrates generally relies on the refractive power of the cornea and crystalline lens to facilitate vision. Light from the environment enters the eye and is refracted by the cornea and lens onto the retina for production of an image. When an animal with a system designed for air submerges underwater, the refractive power of the cornea is lost. Semi-aquatic animals (e.g., water snakes, turtles, aquatic mammals) must overcome this loss of corneal refractive power through visual accommodation. Accommodation relies on change of the position or shape of the lens to change the focal length of the optical system. Intraocular muscles and fibers facilitate lenticular displacement and deformation. Snakes, in general, are largely unstudied in terms of visual acuity and intraocular morphology. I used light microscopy and scanning electron microscopy to examine differences in eye anatomy between five sympatric colubrid snake species (Nerodia cyclopion, N. fasciata, N. rhombifer, Pantherophis obsoletus, and Thamnophis proximus) from Southeast Louisiana. I discovered previously undescribed structures associated with the lens in semi-aquatic species. Photorefractive methods were used to assess refractive error. While all species overcame the expected hyperopia imposed by submergence, there was interspecific variation in refractive error. To assess scaling of eye size with body size, I measure of eye size, head size, and body size in Nerodia cyclopion and N. fasciata from the SLU Vertebrate Museum. In both species, body size increases at a significantly faster rate than head size and eye size (negative allometry). Small snakes have large eyes relative to body size, and large snakes have relatively small eyes. There were interspecific differences in scaling of eye size with body size, where N. fasciata had larger eye diameter, but N. cyclopion had longer eyes (axial length).

  6. "Equilibrium" states of non equilibrium system

    OpenAIRE

    Lev, Bohdan

    2008-01-01

    A possible approach to description of the non equilibrium system has been proposed. Based on the Fokker-Plank equation in term of energy for non equilibrium distribution function of macroscopical system was obtained the stationary solution which can be interpreted as the equilibrium distribution function for new energetic state. The proposed approach takes into account the possible motion between different states of system, induced by dissipation of energy and influence of environment which d...

  7. Cu2Te synthesis and in-vacuum thermal decomposition: Chemical-kinetics analysis and comparison to equilibrium vapor-pressure measurements

    International Nuclear Information System (INIS)

    In this study, polycrystalline Cu-foil substrates are exposed to elemental Te vapor at substrate temperatures below 373 K. Auger electron spectroscopy measurements indicate that copper-telluride films are formed at the substrate surface that have a 2:1 Cu-to-Te ratio, as predicted by the Cu-Te phase diagram. When these films are annealed above about 700 K in vacuum, Te desorbs from the substrate with zero-order kinetics. An analysis of Te-desorption traces that assumes the reaction Cu2Te(s) → 2Cu(s) + αTe(ν) + 1/2(1 - α)Te2(ν) finds a thermal-decomposition activation energy of 217 ± 3 kJ mol-1. These Te-desorption data are compared to the Te impingement rate calculated from Cu2Te equilibrium vapor-pressure data from the literature and found to be in excellent agreement

  8. Honest signaling in domestic piglets (Sus scrofa domesticus): vocal allometry and the information content of grunt calls.

    Science.gov (United States)

    Garcia, Maxime; Wondrak, Marianne; Huber, Ludwig; Fitch, W Tecumseh

    2016-06-15

    The information conveyed in acoustic signals is a central topic in mammal vocal communication research. Body size is one form of information that can be encoded in calls. Acoustic allometry aims to identify the specific acoustic correlates of body size within the vocalizations of a given species, and formants are often a useful acoustic cue in this context. We conducted a longitudinal investigation of acoustic allometry in domestic piglets (Sus scrofa domesticus), asking whether formants of grunt vocalizations provide information concerning the caller's body size over time. On four occasions, we recorded grunts from 20 kunekune piglets, measured their vocal tract length by means of radiographs (X-rays) and weighed them. Controlling for effects of age and sex, we found that body weight strongly predicts vocal tract length, which in turn determines formant frequencies. We conclude that grunt formant frequencies could allow domestic pigs to assess a signaler's body size as it grows. Further research using playback experiments is needed to determine the perceptual role of formants in domestic pig communication. PMID:27059064

  9. Chromatographic speciation of Cr(III)-species, inter-species equilibrium isotope fractionation and improved chemical purification strategies for high-precision isotope analysis

    DEFF Research Database (Denmark)

    Larsen, Kirsten Kolbjørn; Wielandt, Daniel Kim Peel; Schiller, Martin;

    2016-01-01

    in the mass-bias corrected 53Cr/52Cr (μ53Cr* of 5.2ppm) and 54Cr/52Cr (μ54Cr* of 13.5ppm) components used to infer chronometric and nucleosynthetic information in meteorites. To mitigate these fractionation effects, we developed strategic chemical sample pre-treatment procedures that ensure high and...

  10. Isothermal Vapour-Liquid Equilibrium with Chemical Reaction in the Quaternary Water + Methanol + Acetic Acid + Methyl Acetate System, and in Five Binary Subsystems.

    Czech Academy of Sciences Publication Activity Database

    Bernatová, Svatoslava; Aim, Karel; Wichterle, Ivan

    2006-01-01

    Roč. 247, 1-2 (2006) , s. 96-101. ISSN 0378-3812 R&D Projects: GA ČR(CZ) GA203/03/1588 Institutional research plan: CEZ:AV0Z40720504 Keywords : esterification * chemical equilibria * phase equilibria Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.680, year: 2006

  11. Non-equilibrium thermo-chemical heat storage in porous media: Part 2 – A 1D computational model for a calcium hydroxide reaction system

    International Nuclear Information System (INIS)

    Thermal energy storage technologies can facilitate the transition to an energy system based largely on renewable sources and enable efficiency gains for industrial processes in general. Due to their specific advantages, various concepts of thermo-chemical storage systems are being developed. They share characteristic features of mass and heat transport that are strongly coupled through a variety of physical and chemical phenomena. To facilitate the understanding of the coupled multi-physics processes inside such systems, a versatile conceptual model for directly permeated reactive beds was developed in part 1 of this work. It was based on thermodynamic principles and the Theory of Porous Media. The model was then implemented into OpenGeoSys, a scientific finite element simulation software. In this article, the model is specified to the well-studied calcium hydroxide reaction system to illustrate its practical applicability. Sensitivity analyses reveal the influence of particle diameter, porosity, permeability, mass flux, and reaction rate. Two distinct “reaction waves” are identified to migrate through the reactor. The power required to pump the gas stream was decomposed into parts related to the classical mechanical pressure drop and to the chemical reaction. The results can be used for the optimization of thermochemical heat storage systems. - Highlights: • Detailed investigation of coupled multiphysics in thermochemical heat storage. • Thermodynamically consistent model for thermochemical heat storage systems. • Analysis of thermal power depending on material and process parameters. • Two reaction waves are identified that traverse the reactor. • Mechanical pumping power splits into mechanically and chemically induced parts

  12. Conformational plasticity of DM43, a metalloproteinase inhibitor from Didelphis marsupialis: chemical and pressure-induced equilibrium (un)folding studies.

    Science.gov (United States)

    Chapeaurouge, Alex; Martins, Samantha M; Holub, Oliver; Rocha, Surza L G; Valente, Richard H; Neves-Ferreira, Ana G C; Ferreira, Sérgio T; Domont, Gilberto B; Perales, Jonas

    2009-10-01

    We have investigated the folding of DM43, a homodimeric metalloproteinase inhibitor isolated from the serum of the South American opossum Didelphis marsupialis. Denaturation of the protein induced by GdnHCl (guanidine hydrochloride) was monitored by extrinsic and intrinsic fluorescence spectroscopy. While the equilibrium (un)folding of DM43 followed by tryptophan fluorescence was well described by a cooperative two-state transition, bis-ANS (4,4'-dianilino-1,1'-binaphthyl-5,5'-disulfonic acid) fluorescence measurements revealed an intensity maximum at the midpoint of the unfolding transition (2 M GdnHCl), indicating a partially folded intermediate state. We further investigated the DM43 intermediate stabilized at 2 M GdnHCl using size exclusion chromatography. This analysis revealed that the folding intermediate can be best described as partially folded DM43 monomers. Thermodynamic analysis of the GdnHCl-induced denaturation of DM43 revealed Gibbs free-energy changes of 13.57 kcal/mol for dimer dissociation and 1.86 kcal/mol for monomer unfolding, pointing to a critical role of dimerization as a determinant of the structure and stability of this protein. In addition, by using hydrostatic pressure (up to 3.5 kbar) we were able to stabilize partially folded states different from those stabilized in the presence of GdnHCl. Taken together, these results indicate that the conformational plasticity of DM43 could provide this protein with the ability to adapt its conformation to a variety of different environments and biological partners during its biological lifetime. PMID:19332153

  13. Ion exchange equilibrium constants

    CERN Document Server

    Marcus, Y

    2013-01-01

    Ion Exchange Equilibrium Constants focuses on the test-compilation of equilibrium constants for ion exchange reactions. The book first underscores the scope of the compilation, equilibrium constants, symbols used, and arrangement of the table. The manuscript then presents the table of equilibrium constants, including polystyrene sulfonate cation exchanger, polyacrylate cation exchanger, polymethacrylate cation exchanger, polysterene phosphate cation exchanger, and zirconium phosphate cation exchanger. The text highlights zirconium oxide anion exchanger, zeolite type 13Y cation exchanger, and

  14. CHEMICALS

    CERN Multimedia

    Medical Service

    2002-01-01

    It is reminded that all persons who use chemicals must inform CERN's Chemistry Service (TIS-GS-GC) and the CERN Medical Service (TIS-ME). Information concerning their toxicity or other hazards as well as the necessary individual and collective protection measures will be provided by these two services. Users must be in possession of a material safety data sheet (MSDS) for each chemical used. These can be obtained by one of several means : the manufacturer of the chemical (legally obliged to supply an MSDS for each chemical delivered) ; CERN's Chemistry Service of the General Safety Group of TIS ; for chemicals and gases available in the CERN Stores the MSDS has been made available via EDH either in pdf format or else via a link to the supplier's web site. Training courses in chemical safety are available for registration via HR-TD. CERN Medical Service : TIS-ME :73186 or service.medical@cern.ch Chemistry Service : TIS-GS-GC : 78546

  15. Application of a coupled ecosystem-chemical equilibrium model, DayCent-Chem, to stream and soil chemistry in a Rocky Mountain watershed

    Science.gov (United States)

    Hartman, M.D.; Baron, J.S.; Ojima, D.S.

    2007-01-01

    Atmospheric deposition of sulfur and nitrogen species have the potential to acidify terrestrial and aquatic ecosystems, but nitrate and ammonium are also critical nutrients for plant and microbial productivity. Both the ecological response and the hydrochemical response to atmospheric deposition are of interest to regulatory and land management agencies. We developed a non-spatial biogeochemical model to simulate soil and surface water chemistry by linking the daily version of the CENTURY ecosystem model (DayCent) with a low temperature aqueous geochemical model, PHREEQC. The coupled model, DayCent-Chem, simulates the daily dynamics of plant production, soil organic matter, cation exchange, mineral weathering, elution, stream discharge, and solute concentrations in soil water and stream flow. By aerially weighting the contributions of separate bedrock/talus and tundra simulations, the model was able to replicate the measured seasonal and annual stream chemistry for most solutes for Andrews Creek in Loch Vale watershed, Rocky Mountain National Park. Simulated soil chemistry, net primary production, live biomass, and soil organic matter for forest and tundra matched well with measurements. This model is appropriate for accurately describing ecosystem and surface water chemical response to atmospheric deposition and climate change. ?? 2006 Elsevier B.V. All rights reserved.

  16. Ontogenetic allometry constrains cranial shape of the head-first burrowing worm lizard Cynisca leucura (Squamata: Amphisbaenidae).

    Science.gov (United States)

    Hipsley, Christy A; Rentinck, Marc-Nicolas; Rödel, Mark-Oliver; Müller, Johannes

    2016-09-01

    Amphisbaenians are fossorial, predominantly limbless squamate reptiles with distinct cranial shapes corresponding to specific burrowing behaviors. Due to their cryptic lifestyles and the scarcity of museum specimens, little is known of their intraspecific variation, particularly regarding cranial osteology. This represents a critical lack of information, because the majority of morphological investigations of squamate relationships are based on cranial characters. We investigated cranial variation in the West African Coast Worm Lizard Cynisca leucura, a round-headed member of the Amphisbaenidae. Using geometric morphometric analyses of three-dimensional computed tomographic scans, we found that cranial osteology of C. leucura is highly conserved, with the majority of shape changes occurring during growth as the cranium becomes more slender and elongate, accompanied by increasing interdigitation among the dermal roofing bones. Elements of the ventral portion of the cranium remain loosely connected in adults, possibly as a protective mechanism against repeated compression and torsion during burrow excavation. Intraspecific variation was strongly correlated with size change from juveniles to adults, indicating a dominant role of ontogenetic allometry in determining cranial shape. We found no evidence of sexual dimorphism, either during growth or among adults. Given the fossorial habits of C. leucura, we hypothesize that cranial allometry is under strong stabilizing selection to maintain adequate proportions for head-first digging, thereby constraining the ability of individuals to respond to differing selection pressures, including sexual selection and variation in diet or microhabitat. For species in which digging imposes less mechanical stress (e.g., in softer sand), allometric associations during growth may be weakened, allowing changes to the ontogenetic trajectory and subsequent morphological traits. Such developmental dissociation between size and shape, known

  17. ON VECTOR NETWORK EQUILIBRIUM PROBLEMS

    Institute of Scientific and Technical Information of China (English)

    Guangya CHEN

    2005-01-01

    In this paper we define a concept of weak equilibrium for vector network equilibrium problems.We obtain sufficient conditions of weak equilibrium points and establish relation with vector network equilibrium problems and vector variational inequalities.

  18. Equilibrium and generators

    International Nuclear Information System (INIS)

    This work studies the behaviour of radionuclides when it produce a desintegration activity,decay and the isotopes stable creation. It gives definitions about the equilibrium between activity of parent and activity of the daughter, radioactive decay,isotope stable and transient equilibrium and maxim activity time. Some considerations had been given to generators that permit a disgregation of two radioisotopes in equilibrium and its good performance. Tabs

  19. "allometry" Deterministic Approaches in Cell Size, Cell Number and Crude Fiber Content Related to the Physical Quality of Kangkong (Ipomoea reptans) Grown Under Different Plant Density Pressures

    Science.gov (United States)

    Selamat, A.; Atiman, S. A.; Puteh, A.; Abdullah, N. A. P.; Mohamed, M. T. M.; Zulkeefli, A. A.; Othman, S.

    Kangkong, especially the upland type (Ipomoea reptans) is popularly consumed as a vegetable dish in the South East Asian countries for its quality related to Vitamins (A and C) and crude fiber contents. Higher fiber contents would prevent from the occurrence of colon cancer and diverticular disease. With young stem edible portion, its cell number and size contribute to the stem crude fiber content. The mathematical approach of allometry of cell size, number, and fiber content of stem could be used in determining the 'best' plant density pressure in producing the quality young stem to be consumed. Basically, allometry is the ratio of relative increment (growth or change) rates of two parameters, or the change rate associated to the log of measured variables relationship. Kangkog grown equal or lower than 55 plants m-2 produced bigger individual plant and good quality (physical) kangkong leafy vegetable, but with lower total yield per unit area as compared to those grown at higher densities.

  20. Shoot allometry and biomass productivity in poplar and willow varieties grown as short rotation coppice. Summary of results 1995-2000

    Energy Technology Data Exchange (ETDEWEB)

    Matthews, R.; Henshall, P.; Tubby, I.

    2003-07-01

    This report summarises the results of a 4 year study assessing shoot diameters and lengths using non-destructive measurements in order to establish allometric relationships between biomass and non-destructive measurements and also to provide estimates of increments for the development of a model of short rotation cultivation growth and yield. Details are given of the basic methodology and measurement conventions; the data preparation, quality assurance classification and storage; and shoot diameter and length assessments and allometry analyses.

  1. DIAGNOSIS OF FINANCIAL EQUILIBRIUM

    Directory of Open Access Journals (Sweden)

    SUCIU GHEORGHE

    2013-04-01

    Full Text Available The analysis based on the balance sheet tries to identify the state of equilibrium (disequilibrium that exists in a company. The easiest way to determine the state of equilibrium is by looking at the balance sheet and at the information it offers. Because in the balance sheet there are elements that do not reflect their real value, the one established on the market, they must be readjusted, and those elements which are not related to the ordinary operating activities must be eliminated. The diagnosis of financial equilibrium takes into account 2 components: financing sources (ownership equity, loaned, temporarily attracted. An efficient financial equilibrium must respect 2 fundamental requirements: permanent sources represented by ownership equity and loans for more than 1 year should finance permanent needs, and temporary resources should finance the operating cycle.

  2. Non-equilibrium Economics

    Directory of Open Access Journals (Sweden)

    Katalin Martinás

    2007-02-01

    Full Text Available A microeconomic, agent based framework to dynamic economics is formulated in a materialist approach. An axiomatic foundation of a non-equilibrium microeconomics is outlined. Economic activity is modelled as transformation and transport of commodities (materials owned by the agents. Rate of transformations (production intensity, and the rate of transport (trade are defined by the agents. Economic decision rules are derived from the observed economic behaviour. The non-linear equations are solved numerically for a model economy. Numerical solutions for simple model economies suggest that the some of the results of general equilibrium economics are consequences only of the equilibrium hypothesis. We show that perfect competition of selfish agents does not guarantee the stability of economic equilibrium, but cooperativity is needed, too.

  3. Stochastic approach to equilibrium and nonequilibrium thermodynamics.

    Science.gov (United States)

    Tomé, Tânia; de Oliveira, Mário J

    2015-04-01

    We develop the stochastic approach to thermodynamics based on stochastic dynamics, which can be discrete (master equation) and continuous (Fokker-Planck equation), and on two assumptions concerning entropy. The first is the definition of entropy itself and the second the definition of entropy production rate, which is non-negative and vanishes in thermodynamic equilibrium. Based on these assumptions, we study interacting systems with many degrees of freedom in equilibrium or out of thermodynamic equilibrium and how the macroscopic laws are derived from the stochastic dynamics. These studies include the quasiequilibrium processes; the convexity of the equilibrium surface; the monotonic time behavior of thermodynamic potentials, including entropy; the bilinear form of the entropy production rate; the Onsager coefficients and reciprocal relations; and the nonequilibrium steady states of chemical reactions. PMID:25974471

  4. Affine General Equilibrium Models

    OpenAIRE

    Bjørn Eraker

    2008-01-01

    No-arbitrage models are extremely flexible modelling tools but often lack economic motivation. This paper describes an equilibrium consumption-based CAPM framework based on Epstein-Zin preferences, which produces analytic pricing formulas for stocks and bonds under the assumption that macro growth rates follow affine processes. This allows the construction of equilibrium pricing formulas while maintaining the same flexibility of state dynamics as in no-arbitrage models. In demonstrating the a...

  5. Perfect Regular Equilibrium

    OpenAIRE

    hanjoon michael, jung/j

    2010-01-01

    We propose a revised version of the perfect Bayesian equilibrium in general multi-period games with observed actions. In finite games, perfect Bayesian equilibria are weakly consistent and subgame perfect Nash equilibria. In general games that allow a continuum of types and strategies, however, perfect Bayesian equilibria might not satisfy these criteria of rational solution concepts. To solve this problem, we revise the definition of the perfect Bayesian equilibrium by replacing Bayes' rule ...

  6. Intersexual allometry differences and ontogenetic shifts of coloration patterns in two aquatic turtles, Graptemys oculifera and Graptemys flavimaculata.

    Science.gov (United States)

    Ennen, Joshua R; Lindeman, Peter V; Lovich, Jeffrey E

    2015-06-01

    Coloration can play critical roles in a species' biology. The allometry of color patterns may be useful for elucidating the evolutionary mechanisms responsible for shaping the traits. We measured characteristics relating to eight aspects of color patterns from Graptemys oculifera and G. flavimaculata to investigate the allometric differences among male, female, and unsexed juvenile specimens. Additionally, we investigated ontogenetic shifts by incorporating the unsexed juveniles into the male and female datasets. In general, male color traits were isometric (i.e., color scaled with body size), while females and juvenile color traits were hypoallometric, growing in size more slowly than the increase in body size. When we included unsexed juveniles in our male and female datasets, our linear regression analyses found all relationships to be hypoallometric and our model selection analysis found support for nonlinear models describing the relationship between body size and color patterns, suggestive of an ontogenetic shift in coloration traits for both sexes at maturity. Although color is critical for many species' biology and therefore under strong selective pressure in many other species, our results are likely explained by an epiphenomenon related to the different selection pressures on body size and growth rates between juveniles and adults and less attributable to the evolution of color patterns themselves. PMID:26078863

  7. Chemical Equilibrium and Mineral Saturation in Waters from Oil Wells of the Activo Luna Field, Tabasco, Mexico; Equilibrio quimico y grado de saturacion de minerales en aguas de pozos petroleros de Activo Luna, Tabasco, Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Barragan R, Rosa Maria; Arellano G, Victor M.; Portugal M, Enrique; Torres R, Vicente [Instituto de Investigaciones Electricas (Mexico); Torres Alvarado, Ignacio [Universidad Nacional Autonoma de Mexico (Mexico); Ascencio C, Fernando; Martinez A; Ana E [Petroleos Mexicanos (Mexico)

    2001-09-01

    Chemical equilibrium of formation waters from seven oil wells of the Activo Luna field (Tabasco, Mexico) was modelled. Saturation indices of characteristic hydrothermal minerals were calculated at ambient and reservoir conditions in order to predict scaling potential of deep and surface installations. The salinity of waters was found to be in the range from 43,000 (well Escuintle 2) to 250,000 (well Lune 3B) mg/kg as total dissolved solids. The water samples were classified as sodium-chioride type. Ionic strength for the solutions was found to be between 0.75 and 6.5. Activity coefficients were estimated by virial (Pitzer equations) methods using the GEOCHEMIST WORKENCH (GWB) software. Minerals such as anhydrite, halite, alunite, fluorite and barite were found to be supersaturated at reservoir conditions. A solid scale sample obtained from well Luna-3B was analysed. Analysis indicate the presence of calcite, anhydrite, fluorite and sphalerite which suggest the occurrence of temperatures of at least 180 Celcius degrees with acidic conditions and high chemical corrosion potential. [Spanish] Se modelo el equilibrio quimico de aguas de formacion producidas por siete pozos petroleros pertenecientes al Activo Luna, en el estado de Tabasco, Mexico, se calcularon los indices de saturacion de minerales caracteristicos tanto en las condiciones ambiente como en las de yacimiento, con el proposito de apoyar el control de incrustaciones en las instalaciones superficiales y profundas. La salinidad de las salmueras se encontro en el rango de 43,000 (pozos Escuintle 2) a 250,000 (pozos Luna 3B) mg/kg de solidos disueltos totales y las muestras se clasificaron como del tipo clorurado-sodico. La fuerza ionica de las soluciones varia entre 0.75 y 6.5 molar, por lo que los coeficientes de actividad de la modelacion de equilibrio quimico se estimaron por metodos viriales empleando las ecuaciones de Pitzer mediante el programa GEOCHEMIST WORKBENCH (GWB). Minerales como anhidrita, halita

  8. Non-Equilibrium Thermodynamics in Conformal Field Theory

    CERN Document Server

    Hollands, Stephan

    2016-01-01

    We present a model independent, operator algebraic approach to non-equilibrium quantum thermodynamics within the framework of two-dimensional Conformal Field Theory. Two infinite reservoirs in equilibrium at their own temperatures and chemical potentials are put in contact through a defect line, possibly by inserting a probe. As time evolves, the composite system then approaches a non-equilibrium steady state that we describe. In particular, we re-obtain recent formulas of Bernard and Doyon.

  9. Non-Equilibrium Thermodynamics of Self-Replicating Protocells

    OpenAIRE

    Fellermann, Harold; Corominas-Murtra, Bernat; Hansen, Per Lyngs; Ipsen, John Hjort; Solé, Ricard; Rasmussen, Steen

    2015-01-01

    We provide a non-equilibrium thermodynamic description of the life-cycle of a droplet based, chemically feasible, system of protocells. By coupling the protocells metabolic kinetics with its thermodynamics, we demonstrate how the system can be driven out of equilibrium to ensure protocell growth and replication. This coupling allows us to derive the equations of evolution and to rigorously demonstrate how growth and replication life-cycle can be understood as a non-equilibrium thermodynamic c...

  10. Determination of nonaxisymmetric equilibrium

    International Nuclear Information System (INIS)

    The Princeton Equilibrium Code is modified to determine the equilibrium surfaces for a large aspect ratio toroidal system with helical magnetic fields. The code may easily be made to include any variety of modes. Verification of the code is made by comparison with an analytic solution for l = 3. Previously observed shifting of the magnetic axis with increasing pressure or with a changed externally applied vertical field is obtained. The case l = 0, a bumpy torus, gives convergence only for the lenient convergence tolerance of epsilon/sub b/ = 1.0 x 10-2

  11. New insights into non-avian dinosaur reproduction and their evolutionary and ecological implications: linking fossil evidence to allometries of extant close relatives.

    Directory of Open Access Journals (Sweden)

    Jan Werner

    Full Text Available It has been hypothesized that a high reproductive output contributes to the unique gigantism in large dinosaur taxa. In order to infer more information on dinosaur reproduction, we established allometries between body mass and different reproductive traits (egg mass, clutch mass, annual clutch mass for extant phylogenetic brackets (birds, crocodiles and tortoises of extinct non-avian dinosaurs. Allometries were applied to nine non-avian dinosaur taxa (theropods, hadrosaurs, and sauropodomorphs for which fossil estimates on relevant traits are currently available. We found that the reproductive traits of most dinosaurs conformed to similar-sized or scaled-up extant reptiles or birds. The reproductive traits of theropods, which are considered more bird-like, were indeed consistent with birds, while the traits of sauropodomorphs conformed better to reptiles. Reproductive traits of hadrosaurs corresponded to both reptiles and birds. Excluding Massospondyluscarinatus, all dinosaurs studied had an intermediary egg to body mass relationship to reptiles and birds. In contrast, dinosaur clutch masses fitted with either the masses predicted from allometries of birds (theropods or to the masses of reptiles (all other taxa. Theropods studied had probably one clutch per year. For sauropodomorphs and hadrosaurs, more than one clutch per year was predicted. Contrary to current hypotheses, large dinosaurs did not have exceptionally high annual egg numbers (AEN. Independent of the extant model, the estimated dinosaur AEN did not exceed 850 eggs (75,000 kg sauropod for any of the taxa studied. This estimated maximum is probably an overestimation due to unrealistic assumptions. According to most AEN estimations, the dinosaurs studied laid less than 200 eggs per year. Only some AEN estimates obtained for medium to large sized sauropods were higher (200-400 eggs. Our results provide new (testable hypotheses, especially for reproductive traits that are insufficiently

  12. Statistical fluctuations and correlations in hadronic equilibrium systems

    International Nuclear Information System (INIS)

    This thesis is dedicated to the study of fluctuation and correlation observables of hadronic equilibrium systems. The statistical hadronization model of high energy physics, in its ideal, i.e. non-interacting, gas approximation is investigated in different ensemble formulations. The hypothesis of thermal and chemical equilibrium in high energy interaction is tested against qualitative and quantitative predictions. (orig.)

  13. Statistical fluctuations and correlations in hadronic equilibrium systems

    Energy Technology Data Exchange (ETDEWEB)

    Hauer, Michael

    2010-06-17

    This thesis is dedicated to the study of fluctuation and correlation observables of hadronic equilibrium systems. The statistical hadronization model of high energy physics, in its ideal, i.e. non-interacting, gas approximation is investigated in different ensemble formulations. The hypothesis of thermal and chemical equilibrium in high energy interaction is tested against qualitative and quantitative predictions. (orig.)

  14. An Updated Equilibrium Machine

    Science.gov (United States)

    Schultz, Emeric

    2008-01-01

    A device that can demonstrate equilibrium, kinetic, and thermodynamic concepts is described. The device consists of a leaf blower attached to a plastic container divided into two chambers by a barrier of variable size and form. Styrofoam balls can be exchanged across the barrier when the leaf blower is turned on and various air pressures are…

  15. Absence of equilibrium chiral magnetic effect

    CERN Document Server

    Zubkov, M A

    2016-01-01

    We analyse the $3+1$ D equilibrium chiral magnetic effect (CME). We apply derivative expansion to the Wigner transform of the two - point Green function. This technique allows us to express the response of electric current to external electromagnetic field strength through the momentum space topological invariant. We consider the wide class of the lattice regularizations of quantum field theory (that includes, in particular, the regularization with Wilson fermions) and also certain lattice models of solid state physics (including those of Dirac semimetals). It appears, that in these models the mentioned topological invariant vanishes identically at nonzero chiral chemical potential. That means, that the bulk equilibrium CME is absent in those systems.

  16. Far-from-equilibrium kinetic processes

    Science.gov (United States)

    Rubí, J. Miguel; Pérez-Madrid, Agustin

    2015-12-01

    We analyze the kinetics of activated processes that take place under far-from-equilibrium conditions, when the system is subjected to external driving forces or gradients or at high values of affinities. We use mesoscopic non-equilibrium thermodynamics to show that when a force is applied, the reaction rate depends on the force. In the case of a chemical reaction at high affinity values, the reaction rate is no longer constant but depends on affinity, which implies that the law of mass action is no longer valid. This result is in good agreement with the kinetic theory of reacting gases, which uses a Chapman-Enskog expansion of the probability distribution.

  17. Allometric scaling of population variance with mean body size is predicted from Taylor’s law and density-mass allometry

    OpenAIRE

    Cohen, Joel E.; Xu, Meng; Schuster, William S. F.

    2012-01-01

    Two widely tested empirical patterns in ecology are combined here to predict how the variation of population density relates to the average body size of organisms. Taylor’s law (TL) asserts that the variance of the population density of a set of populations is a power-law function of the mean population density. Density–mass allometry (DMA) asserts that the mean population density of a set of populations is a power-law function of the mean individual body mass. Combined, DMA and TL predict th...

  18. Mesoscopic thermodynamics of stationary non-equilibrium states

    International Nuclear Information System (INIS)

    Thermodynamics for systems at non-equilibrium stationary states have been formulated, based on the assumption of the existence of a local equilibrium in phase space which enables one to interpret the probability density and its conjugated non-equilibrium chemical potential as mesoscopic thermodynamic variables. The probability current is obtained from the entropy production related to the probability diffusion process and leads to the formulation of the Fokker-Planck equation. For the case of a gas of Brownian particles under steady flow in the dilute and concentrated regimes, we derive non-equilibrium equations of state

  19. Non-equilibrium quantum heat machines

    Science.gov (United States)

    Alicki, Robert; Gelbwaser-Klimovsky, David

    2015-11-01

    Standard heat machines (engine, heat pump, refrigerator) are composed of a system (working fluid) coupled to at least two equilibrium baths at different temperatures and periodically driven by an external device (piston or rotor) sometimes called the work reservoir. The aim of this paper is to go beyond this scheme by considering environments which are stationary but cannot be decomposed into a few baths at thermal equilibrium. Such situations are important, for example in solar cells, chemical machines in biology, various realizations of laser cooling or nanoscopic machines driven by laser radiation. We classify non-equilibrium baths depending on their thermodynamic behavior and show that the efficiency of heat machines powered by them is limited by the generalized Carnot bound.

  20. Non-Equilibrium Thermodynamics in Multiphase Flows

    CERN Document Server

    Mauri, Roberto

    2013-01-01

    Non-equilibrium thermodynamics is a general framework that allows the macroscopic description of irreversible processes. This book introduces non-equilibrium thermodynamics and its applications to the rheology of multiphase flows. The subject is relevant to graduate students in chemical and mechanical engineering, physics and material science. This book is divided into two parts. The first part presents the theory of non-equilibrium thermodynamics, reviewing its essential features and showing, when possible, some applications. The second part of this book deals with how the general theory can be applied to model multiphase flows and, in particular, how to determine their constitutive relations. Each chapter contains problems at the end, the solutions of which are given at the end of the book. No prior knowledge of statistical mechanics is required; the necessary prerequisites are elements of transport phenomena and on thermodynamics. “The style of the book is mathematical, but nonetheless it remains very re...

  1. Problems in equilibrium theory

    CERN Document Server

    Aliprantis, Charalambos D

    1996-01-01

    In studying General Equilibrium Theory the student must master first the theory and then apply it to solve problems. At the graduate level there is no book devoted exclusively to teaching problem solving. This book teaches for the first time the basic methods of proof and problem solving in General Equilibrium Theory. The problems cover the entire spectrum of difficulty; some are routine, some require a good grasp of the material involved, and some are exceptionally challenging. The book presents complete solutions to two hundred problems. In searching for the basic required techniques, the student will find a wealth of new material incorporated into the solutions. The student is challenged to produce solutions which are different from the ones presented in the book.

  2. TBR-2 MHD equilibrium

    International Nuclear Information System (INIS)

    Determinations of many possible equilibrium configurations in a device is one of the most important phases of the project in the sense that plasma configurations basically determine the details of the machine project. Details as limiters, vacuum vessel configuration and the position of vertical field or shapping field coils. Recent progress of tokamaks with non circular poloidal section in the formation of different plasma shapes compared to traditional circular ones, made the determination of MHD equilibrium and becomes more essential. Tokamak TBR-2, to be constructed at the Institute of Physics of the University of Sao Paulo, is a device with this non-traditional quality. This paper shows the simulation results obtained for the TBR-2. (Author)

  3. Gated equilibrium bloodpool scintigraphy

    International Nuclear Information System (INIS)

    This thesis deals with the clinical applications of gated equilibrium bloodpool scintigraphy, performed with either a gamma camera or a portable detector system, the nuclear stethoscope. The main goal has been to define the value and limitations of noninvasive measurements of left ventricular ejection fraction as a parameter of cardiac performance in various disease states, both for diagnostic purposes as well as during follow-up after medical or surgical intervention. Secondly, it was attempted to extend the use of the equilibrium bloodpool techniques beyond the calculation of ejection fraction alone by considering the feasibility to determine ventricular volumes and by including the possibility of quantifying valvular regurgitation. In both cases, it has been tried to broaden the perspective of the observations by comparing them with results of other, invasive and non-invasive, procedures, in particular cardiac catheterization, M-mode echocardiography and myocardial perfusion scintigraphy. (Auth.)

  4. Equilibrium Cost Overruns

    OpenAIRE

    Yongmin Chen; Ron Smith

    2001-01-01

    Cost overruns are endemic in military procurement projects and pervasive in other areas. This paper studies a model in which the apparent cost overruns arise not as systematic expectational errors but as equilibrium phenomena. The possibility of renegotiating payments when cost overruns occur results in firms bidding below their true estimate of expected project costs. This can cause the initial price for a project to be consistently lower than its expected cost, and hence the persistence of ...

  5. Volatility in Equilibrium

    DEFF Research Database (Denmark)

    Bollerslev, Tim; Sizova, Natalia; Tauchen, George

    Stock market volatility clusters in time, carries a risk premium, is fractionally inte- grated, and exhibits asymmetric leverage effects relative to returns. This paper develops a first internally consistent equilibrium based explanation for these longstanding empirical facts. The model is cast i......, and the dynamic cross-correlations of the volatility measures with the returns calculated from actual high-frequency intra-day data on the S&P 500 aggregate market and VIX volatility indexes....

  6. Bluffing: an equilibrium strategy

    OpenAIRE

    Fabrice Rousseau

    1999-01-01

    The present work studies the behavior of a monopolistic informed trader in a two-period competitive dealer market. We show that the informed trader may engage in stock price manipulation as a result of the exploitation of his informational advantage (sufficient conditions are provided). The informed trader achieves this manipulation by not trading in the first period according to the information received. This trader attempts to jam his signal or to bluff. In equilibrium this behavior is anti...

  7. Equilibrium statistical mechanics

    CERN Document Server

    Jackson, E Atlee

    2000-01-01

    Ideal as an elementary introduction to equilibrium statistical mechanics, this volume covers both classical and quantum methodology for open and closed systems. Introductory chapters familiarize readers with probability and microscopic models of systems, while additional chapters describe the general derivation of the fundamental statistical mechanics relationships. The final chapter contains 16 sections, each dealing with a different application, ordered according to complexity, from classical through degenerate quantum statistical mechanics. Key features include an elementary introduction t

  8. Tourism Equilibrium Price Trends

    Directory of Open Access Journals (Sweden)

    Mohammad Mohebi

    2012-01-01

    Full Text Available Problem statement: A review of the tourism history shows that tourism as an industry was virtually unknown in Malaysia until the late 1960s. Since then, it has developed and grown into a major industry, making an important contribution to the country's economy. By allocating substantial funds to the promotion of tourism and the provision of the necessary infrastructure, the government has played an important role in the impressive progress of the Malaysian tourism industry. One of the important factors which can attract tourists to Malaysia is the tourism price. Has the price of tourism decreased? To answer this question, it is necessary to obtain the equilibrium prices as well as the yearly trend for Malaysia during the sample period as it will be useful for analysis of the infrastructure situation of the tourism industry in this country. The purpose of the study is to identify equilibrium tourism price trends in Malaysian tourism market. Approach: We use hotel room as representative of tourism market. Quarterly data from 1995-2009 are used and a dynamic model of simultaneous equation is employed. Results: Based on the result during the period of 1995 until 2000, the growth rate of the equilibrium price was greater than consumer price index and producer price index. Conclusion: In the Malaysian tourism market, new infrastructure during this period had not been developed to keep pace with tourist arrivals.

  9. Quantifying the Variability of Internode Allometry within and between Trees for Pinus tabulaeformis Carr. Using a Multilevel Nonlinear Mixed-Effect Model

    Directory of Open Access Journals (Sweden)

    Jun Diao

    2014-11-01

    Full Text Available Allometric models of internodes are an important component of Functional-Structural Plant Models (FSPMs, which represent the shape of internodes in tree architecture and help our understanding of resource allocation in organisms. Constant allometry is always assumed in these models. In this paper, multilevel nonlinear mixed-effect models were used to characterize the variability of internode allometry, describing the relationship between the last internode length and biomass of Pinus tabulaeformis Carr. trees within the GreenLab framework. We demonstrated that there is significant variability in allometric relationships at the tree and different-order branch levels, and the variability decreases among levels from trees to first-order branches and, subsequently, to second-order branches. The variability was partially explained by the random effects of site characteristics, stand age, density, and topological position of the internode. Tree- and branch-level-specific allometric models are recommended because they produce unbiased and accurate internode length estimates. The model and method developed in this study are useful for understanding and describing the structure and functioning of trees.

  10. Pitch (F0) and formant profiles of human vowels and vowel-like baboon grunts: The role of vocalizer body size and voice-acoustic allometry

    Science.gov (United States)

    Rendall, Drew; Kollias, Sophie; Ney, Christina; Lloyd, Peter

    2005-02-01

    Key voice features-fundamental frequency (F0) and formant frequencies-can vary extensively between individuals. Much of the variation can be traced to differences in the size of the larynx and vocal-tract cavities, but whether these differences in turn simply reflect differences in speaker body size (i.e., neutral vocal allometry) remains unclear. Quantitative analyses were therefore undertaken to test the relationship between speaker body size and voice F0 and formant frequencies for human vowels. To test the taxonomic generality of the relationships, the same analyses were conducted on the vowel-like grunts of baboons, whose phylogenetic proximity to humans and similar vocal production biology and voice acoustic patterns recommend them for such comparative research. For adults of both species, males were larger than females and had lower mean voice F0 and formant frequencies. However, beyond this, F0 variation did not track body-size variation between the sexes in either species, nor within sexes in humans. In humans, formant variation correlated significantly with speaker height but only in males and not in females. Implications for general vocal allometry are discussed as are implications for speech origins theories, and challenges to them, related to laryngeal position and vocal tract length. .

  11. Equilibrium Gold Nanoclusters Quenched with Biodegradable Polymers

    OpenAIRE

    Murthy, Avinash K.; Stover, Robert J.; Borwankar, Ameya U.; Nie, Golay D.; Gourisankar, Sai; Truskett, Thomas M.; Konstantin V. Sokolov; Johnston, Keith P.

    2012-01-01

    Although sub-100 nm nanoclusters of metal nanoparticles are of interest in many fields including biomedical imaging, sensors and catalysis, it has been challenging to control their morphologies and chemical properties. Herein, a new concept is presented to assemble equilibrium Au nanoclusters of controlled size by tuning the colloidal interactions with a polymeric stabilizer, PLA(1k)-b-PEG(10k)-b-PLA(1k). The nanoclusters form upon mixing a dispersion of ~5 nm Au nanospheres with a polymer so...

  12. Non-equilibrium thermodynamics

    CERN Document Server

    Groot, S R De

    2011-01-01

    The study of thermodynamics is especially timely today, as its concepts are being applied to problems in biology, biochemistry, electrochemistry, and engineering. This book treats irreversible processes and phenomena - non-equilibrium thermodynamics.S. R. de Groot and P. Mazur, Professors of Theoretical Physics, present a comprehensive and insightful survey of the foundations of the field, providing the only complete discussion of the fluctuating linear theory of irreversible thermodynamics. The application covers a wide range of topics: the theory of diffusion and heat conduction, fluid dyn

  13. Money in search equilibrium, in competitive equilibrium, and in competitive search equilibrium

    OpenAIRE

    Randall Wright; Guillame Rocheteau

    2004-01-01

    We compare three pricing mechanisms for monetary economies: bargaining (search equilibrium); price taking (competitive equilibrium); and price posting (competitive search equilibrium). We do this in a framework that, in addition to considering different mechanisms, extends existing work on the microfoundations of money by allowing a general matching technology and endogenous entry. We study how the nature of equilibrium and effects of policy depend on the mechanism. Under bargaining, trades a...

  14. Statistical physics ""Beyond equilibrium

    Energy Technology Data Exchange (ETDEWEB)

    Ecke, Robert E [Los Alamos National Laboratory

    2009-01-01

    The scientific challenges of the 21st century will increasingly involve competing interactions, geometric frustration, spatial and temporal intrinsic inhomogeneity, nanoscale structures, and interactions spanning many scales. We will focus on a broad class of emerging problems that will require new tools in non-equilibrium statistical physics and that will find application in new material functionality, in predicting complex spatial dynamics, and in understanding novel states of matter. Our work will encompass materials under extreme conditions involving elastic/plastic deformation, competing interactions, intrinsic inhomogeneity, frustration in condensed matter systems, scaling phenomena in disordered materials from glasses to granular matter, quantum chemistry applied to nano-scale materials, soft-matter materials, and spatio-temporal properties of both ordinary and complex fluids.

  15. Non-equilibrium chemistry in the atmospheres of brown dwarfs

    CERN Document Server

    Saumon, D S; Freedman, R S; Lodders, K

    2002-01-01

    Carbon monoxide and ammonia have been detected in the spectrum of Gl 229B at abundances that differ substantially from those obtained from chemical equilibrium. Vertical mixing in the atmosphere is a mechanism that can drive slowly reacting species out of chemical equilibrium. We explore the effects of vertical mixing as a function of mixing efficiency and effective temperature on the chemical abundances in the atmospheres of brown dwarfs and on their spectra. The models compare favorably with the observational evidence and indicate that vertical mixing plays an important role in brown dwarf atmospheres.

  16. Exploring Equilibrium Chemistry for Hot Exoplanets

    Science.gov (United States)

    Blumenthal, Sarah; Harrington, Joseph; Mandell, Avi; Hébrard, Eric; Venot, Olivia; Cubillos, Patricio; Challener, Ryan

    2015-11-01

    It has been established that equilibrium chemistry is usually achieved deep in the atmosphere of hot Jovians where timescales are short (Line and Young 2013). Thus, equilibrium chemistry has been used as a starting point (setting initial conditions) for evaluating disequilibrium processes. We explore parameters of setting these initial conditions including departures from solar metallicity, the number of species allowed in a system, the types of species allowed in a system, and different thermodynamic libraries in an attempt to create a standard for evaluating equilibrium chemistry. NASA's open source code Chemical Equilibrium and Applications (CEA) is used to calculate model planet abundances by varying the metallicity, in the pressure regime of 0.1 to 1 bar. These results are compared to a variety of exoplanets (Teq between 600 and 2100K) qualitatively by color maps of the dayside with different temperature redistributions. Additionally, CEA (with an updated thermodynamic library) is validated with the thermochemical model presented in Venot et al. (2012) for HD 209458b and HD 189733b. This same analysis has then been extended to the cooler planet HD 97658b. Spectra are generated from both models’ abundances using the open source code transit (https://github.com/exosports/transit) using the opacities of 15 molecules. We make the updated CEA thermodyanamic library and supporting Python scripts to do the CEA analyses available open source. This work was supported by NASA Planetary Atmospheres grant NNX12AI69G.

  17. Control of the Accumulation of Non-Process Elements in Pulp Mills with Bleach Filtrate Reuse: A Chemical Equilibrium Approach to Predicting the Partitioning of Metals in Pulp Mill and Bleach Plant Streams

    Energy Technology Data Exchange (ETDEWEB)

    Frederick, W.J. Jr.; Rudie, A.W.; Schmidl, G.W.; Sinquefield, S.A.; Rorrer, G.L.; Laver, M.L.; Yantasee, W.; Ming, D.

    2000-08-01

    The overall goal of this project was to develop fundamental, experimentally based methods for predicting the solubility or organic and inorganic matter and their interactions in recycled effluent from kraft pulp mills and bleach plants. This included: characterizing the capacity of wood pulp and dissolved organic matter to bind metal ions, developing a thermodynamic database of properties needed to describe the solubility of inorganic matter in pulp mill streams, incorporation of the database into equilibrium calculation software for predicting the solubility of the metals of interest, and evaluating its capability to predict the distribution of the metals between pulp fibers, inorganic precipitates, and solution.

  18. Ontogenetic Tooth Reduction in Stenopterygius quadriscissus (Reptilia: Ichthyosauria): Negative Allometry, Changes in Growth Rate, and Early Senescence of the Dental Lamina

    Science.gov (United States)

    Dick, Daniel G.; Maxwell, Erin E.

    2015-01-01

    We explore the functional, developmental, and evolutionary processes which are argued to produce tooth reduction in the extinct marine reptile Stenopterygius quadriscissus (Reptilia: Ichthyosauria). We analyze the relationship between mandible growth and tooth size, shape, and count, to establish an ontogenetic trend. The pattern in S. quadriscissus is consistent with hypotheses of tooth size reduction by neutral selection, and this unusual morphology (a functionally edentulous rostrum) was produced by a series of different evolutionary developmental changes that are known for other taxa showing tooth reduction and loss. Specifically, this species evolved functional edentulism by evolutionary changes in the growth allometry of the dentition and by altering growth rates through ontogeny. This observation supports previous hypotheses that S. quadriscissus underwent ontogenetic tooth reduction. Tooth reduction in S. quadriscissus may be caused by unique selective pressures resulting from prey choice and feeding behavior, expanding our current understanding of the mechanisms producing tooth reduction. PMID:26579712

  19. Ontogenetic Tooth Reduction in Stenopterygius quadriscissus (Reptilia: Ichthyosauria: Negative Allometry, Changes in Growth Rate, and Early Senescence of the Dental Lamina.

    Directory of Open Access Journals (Sweden)

    Daniel G Dick

    Full Text Available We explore the functional, developmental, and evolutionary processes which are argued to produce tooth reduction in the extinct marine reptile Stenopterygius quadriscissus (Reptilia: Ichthyosauria. We analyze the relationship between mandible growth and tooth size, shape, and count, to establish an ontogenetic trend. The pattern in S. quadriscissus is consistent with hypotheses of tooth size reduction by neutral selection, and this unusual morphology (a functionally edentulous rostrum was produced by a series of different evolutionary developmental changes that are known for other taxa showing tooth reduction and loss. Specifically, this species evolved functional edentulism by evolutionary changes in the growth allometry of the dentition and by altering growth rates through ontogeny. This observation supports previous hypotheses that S. quadriscissus underwent ontogenetic tooth reduction. Tooth reduction in S. quadriscissus may be caused by unique selective pressures resulting from prey choice and feeding behavior, expanding our current understanding of the mechanisms producing tooth reduction.

  20. Ontogenetic Tooth Reduction in Stenopterygius quadriscissus (Reptilia: Ichthyosauria): Negative Allometry, Changes in Growth Rate, and Early Senescence of the Dental Lamina.

    Science.gov (United States)

    Dick, Daniel G; Maxwell, Erin E

    2015-01-01

    We explore the functional, developmental, and evolutionary processes which are argued to produce tooth reduction in the extinct marine reptile Stenopterygius quadriscissus (Reptilia: Ichthyosauria). We analyze the relationship between mandible growth and tooth size, shape, and count, to establish an ontogenetic trend. The pattern in S. quadriscissus is consistent with hypotheses of tooth size reduction by neutral selection, and this unusual morphology (a functionally edentulous rostrum) was produced by a series of different evolutionary developmental changes that are known for other taxa showing tooth reduction and loss. Specifically, this species evolved functional edentulism by evolutionary changes in the growth allometry of the dentition and by altering growth rates through ontogeny. This observation supports previous hypotheses that S. quadriscissus underwent ontogenetic tooth reduction. Tooth reduction in S. quadriscissus may be caused by unique selective pressures resulting from prey choice and feeding behavior, expanding our current understanding of the mechanisms producing tooth reduction. PMID:26579712

  1. Non-Equilibrium Thermodynamics of Self-Replicating Protocells

    DEFF Research Database (Denmark)

    Fellermann, Harold; Corominas-Murtra, Bernat; Hansen, Per Lyngs;

    2016-01-01

    We provide a non-equilibrium thermodynamic description of the life-cycle of a droplet based, chemically feasible, system of protocells. By coupling the protocells metabolic kinetics with its thermodynamics, we demonstrate how the system can be driven out of equilibrium to ensure protocell growth...... and replication. This coupling allows us to derive the equations of evolution and to rigorously demonstrate how growth and replication life-cycle can be understood as a non-equilibrium thermodynamic cycle. The process does not appeal to genetic information or inheritance, and is based only on non......-equilibrium physics considerations. Our non-equilibrium thermodynamic description of simple, yet realistic, processes of protocell growth and replication, represents an advance in our physical understanding of a central biological phenomenon both in connection to the origin of life and for modern biology....

  2. Equilibrium models and variational inequalities

    CERN Document Server

    Konnov, Igor

    2007-01-01

    The concept of equilibrium plays a central role in various applied sciences, such as physics (especially, mechanics), economics, engineering, transportation, sociology, chemistry, biology and other fields. If one can formulate the equilibrium problem in the form of a mathematical model, solutions of the corresponding problem can be used for forecasting the future behavior of very complex systems and, also, for correcting the the current state of the system under control. This book presents a unifying look on different equilibrium concepts in economics, including several models from related sciences.- Presents a unifying look on different equilibrium concepts and also the present state of investigations in this field- Describes static and dynamic input-output models, Walras, Cassel-Wald, spatial price, auction market, oligopolistic equilibrium models, transportation and migration equilibrium models- Covers the basics of theory and solution methods both for the complementarity and variational inequality probl...

  3. Nash equilibrium with Sugeno payoff

    OpenAIRE

    Radul, Taras

    2015-01-01

    This paper is devoted to Nash equilibrium for games in capacities. Such games with payoff expressed by Choquet integral were considered by Kozhan and Zarichnyi (Nash equilibria for games in capacities, Econ. Theory {\\bf 35} (2008) 321--331) and existence of Nash equilibrium was proved. We also consider games in capacities but with expected payoff expressed by Sugeno integral. We prove existence of Nash equilibrium using categorical methods and abstract convexity theory.

  4. Models for Equilibrium BEC Superradiance

    CERN Document Server

    Pulé, J V; Zagrebnov, V A; Pule, Joseph V.; Verbeure, Andre; Zagrebnov, Valentin A.

    2004-01-01

    Motivated by recent experiments with superradiant Bose-Einstein Condensate (BEC) we consider simple microscopic models describing rigorously the interference of the two cooperative phenomena, BEC and radiation, in thermodynamic equilibrium. Our resuts in equilibrium confirm the presence of the observed superradiant light scattering from BEC: (a) the equilibrium superradiance exists only below a certain transition temperature; (b) there is superradiance and matter-wave (BEC) enhancement due to the coherent coupling between light and matter.

  5. Models for Equilibrium BEC Superradiance

    OpenAIRE

    Pule, Joseph V.; Verbeure, Andre; Zagrebnov, Valentin A.

    2004-01-01

    Motivated by recent experiments with superradiant Bose-Einstein Condensate (BEC) we consider simple microscopic models describing rigorously the interference of the two cooperative phenomena, BEC and radiation, in thermodynamic equilibrium. Our resuts in equilibrium confirm the presence of the observed superradiant light scattering from BEC: (a) the equilibrium superradiance exists only below a certain transition temperature; (b) there is superradiance and matter-wave (BEC) enhancement due to...

  6. Models for equilibrium BEC superradiance

    International Nuclear Information System (INIS)

    Motivated by recent experiments with superradiant Bose-Einstein condensate (BEC) we consider simple microscopic models describing rigorously the interference of the two cooperative phenomena, BEC and radiation, in thermodynamic equilibrium. Our results in equilibrium confirm the presence of the observed superradiant light scattering from BEC: (a) the equilibrium superradiance exists only below a certain transition temperature; (b) there is superradiance and matter-wave (BEC) enhancement due to the coherent coupling between light and matter. (letter to the editor)

  7. Equilibrium Electro-osmotic Instability

    OpenAIRE

    Rubinstein, Isaak; Zaltzman, Boris

    2014-01-01

    Since its prediction fifteen years ago, electro-osmotic instability has been attributed to non-equilibrium electro-osmosis related to the extended space charge which develops at the limiting current in the course of concentration polarization at a charge-selective interface. This attribution had a double basis. Firstly, it has been recognized that equilibrium electro-osmosis cannot yield instability for a perfectly charge-selective solid. Secondly, it has been shown that non-equilibrium elect...

  8. Equilibrium Thermodynamics Of Materials At Non-pvt System

    International Nuclear Information System (INIS)

    This book introduces thermodynamic principle, thermodynamic state function and Maxwell equation with Helmholtz's free energy and using case of Maxwell equation, electrochemistry at interface such as conception of electrode, pourbaix's diagram and electrochemical cells, surface phenomenon like definition of surface energy and steam pressure, thermodynamic equilibrium of a magnetometer, and a reversible cell, chemical potential, Gibbs' phase rule in equilibrium and statistical thermodynamics.

  9. Non-equilibrium chemistry in space

    International Nuclear Information System (INIS)

    Chemical processes by accelerated species do not proceed in thermal equilibrium with the target molecules. The hot or suprathermal reactions are characterized by the fact that a kinetic energy ranging from about 1 to few 10 eV is imparted to the collision complex. Reaction rates are by orders of magnitude higher and products are more diversified than in classic thermally controlled reactions. Space is rich in energetic atoms, ions, molecules, fragments, clusters, and grains from cosmic rays, solar or stellar radiation, shock waves and many secondary acceleration processes with energies ranging from a few eV (photodissociation) to some TeV (cosmic rays). Non-equilibrium chemistry is, thus, typical for space. Suprathermal reactions in the solid state can effectively compete with radiolysis or photolysis and ion molecule interactions, particularly in view of the formation of complex organic matter by multicenter reactions in the collision cascades. (orig.)

  10. Line radiative transfer and statistical equilibrium*

    Directory of Open Access Journals (Sweden)

    Kamp Inga

    2015-01-01

    Full Text Available Atomic and molecular line emission from protoplanetary disks contains key information of their detailed physical and chemical structures. To unravel those structures, we need to understand line radiative transfer in dusty media and the statistical equilibrium, especially of molecules. I describe here the basic principles of statistical equilibrium and illustrate them through the two-level atom. In a second part, the fundamentals of line radiative transfer are introduced along with the various broadening mechanisms. I explain general solution methods with their drawbacks and also specific difficulties encountered in solving the line radiative transfer equation in disks (e.g. velocity gradients. I am closing with a few special cases of line emission from disks: Radiative pumping, masers and resonance scattering.

  11. Simplex characterization of equilibrium

    International Nuclear Information System (INIS)

    Minimization of the reaction isotherm absolute value by the sequential simplex method may be used to characterize the equilibrium valence state distribution of plutonium in aqueous solutions. Sequential simplex procedure is an empirical method of locating maxima or minima in the response of a function of several variables. Where the objective function is entirely mathematical, a computer may be used to perform the simplex operations in a rapid and accurate manner, so that maxima and minima can often be located quickly and easily. The disproportionation of tetravalent plutonium is considered to be the consequence of two sequential reactions: 2Pu4+ + 2HOH = Pu3+ + PuO2+ + 4H+ P (1). Pu4+ + PuO2+ = Pu3+ + PuO2+ Q (2). If P is the frequency of occurrence of Eq. (1), and Q is the frequency of occurrence of Eq. (2), then it is assumed, that P=Q, and Eqs (1) and (2) may be added directly. 3Pu4+ + 2HOH = 2Pu3+ + PuO22+ + 4H+ (3). The persistence of pentavalent plutonium in aqueous plutonium solutions suggests that reactions 1 and 2 are not of equal frequency, and that their proportion for purposes of addition is not exactly equal to 1:1. (T.I.)

  12. Kinetic equilibrium and relativistic thermodynamics

    OpenAIRE

    Ván P.

    2011-01-01

    Relativistic thermodynamics is treated from the point of view of kinetic theory. It is shown that the generalized J\\"uttner distribution suggested in [1] is compatible with kinetic equilibrium. The requirement of compatibility of kinetic and thermodynamic equilibrium reveals several generalizations of the Gibbs relation where the velocity field is an independent thermodynamic variable.

  13. Non-equilibrium phase transitions

    CERN Document Server

    Henkel, Malte; Lübeck, Sven

    2009-01-01

    This book describes two main classes of non-equilibrium phase-transitions: (a) static and dynamics of transitions into an absorbing state, and (b) dynamical scaling in far-from-equilibrium relaxation behaviour and ageing. The first volume begins with an introductory chapter which recalls the main concepts of phase-transitions, set for the convenience of the reader in an equilibrium context. The extension to non-equilibrium systems is made by using directed percolation as the main paradigm of absorbing phase transitions and in view of the richness of the known results an entire chapter is devoted to it, including a discussion of recent experimental results. Scaling theories and a large set of both numerical and analytical methods for the study of non-equilibrium phase transitions are thoroughly discussed. The techniques used for directed percolation are then extended to other universality classes and many important results on model parameters are provided for easy reference.

  14. A Multiperiod Equilibrium Pricing Model

    Directory of Open Access Journals (Sweden)

    Minsuk Kwak

    2014-01-01

    Full Text Available We propose an equilibrium pricing model in a dynamic multiperiod stochastic framework with uncertain income. There are one tradable risky asset (stock/commodity, one nontradable underlying (temperature, and also a contingent claim (weather derivative written on the tradable risky asset and the nontradable underlying in the market. The price of the contingent claim is priced in equilibrium by optimal strategies of representative agent and market clearing condition. The risk preferences are of exponential type with a stochastic coefficient of risk aversion. Both subgame perfect strategy and naive strategy are considered and the corresponding equilibrium prices are derived. From the numerical result we examine how the equilibrium prices vary in response to changes in model parameters and highlight the importance of our equilibrium pricing principle.

  15. Hot nuclear matter and thermodynamical equilibrium

    International Nuclear Information System (INIS)

    Quasi-complete events from collisions between 36Ar and 58Ni corresponding to vaporized sources have been detected with the multidetector INDRA over the excitation energy range 10 - 28 AMeV. For the first time complete information concerning kinematical properties of emitted particles and chemical composition (mean values but also variances) are derived. Despite the very extreme conditions in which such sources are produced (binary collisions with short reaction times and source life-times), their properties are in agreement with the results of a statistical model including a final state excluded volume interaction and describing a gas of fermions and bosons in thermodynamical equilibrium. (authors)

  16. Multivariate allometry and myocardium abnormalities during experimental systemic nitric oxide blockage Alometria multivariada e anormalidades do miocárdio durante bloqueio sistêmico da síntese de óxido nítrico

    OpenAIRE

    Ricardo Xavier-Vidal; Santiago Segundo Ramirez Carvajal; Sônia Baptista da Cunha; Kalil Madi

    2004-01-01

    Using allometry to evaluate numerical data from normal and experimental hypertensive rats' myocardium, thirteen normotensive Wistar male young rats were examined. Hearts were processed using histological routine methods. For myocardial quantification we utilized an M-42 Test-System. Fifteen fields were randomly considered. Parameters utilized: volumetric density (Vv %); volume (V µm³) and cardiac weight. The chi2 proposed by Anderson and the F proposed by Jolicoeur were utilized to test the i...

  17. TEA: A Code Calculating Thermochemical Equilibrium Abundances

    Science.gov (United States)

    Blecic, Jasmina; Harrington, Joseph; Bowman, M. Oliver

    2016-07-01

    We present an open-source Thermochemical Equilibrium Abundances (TEA) code that calculates the abundances of gaseous molecular species. The code is based on the methodology of White et al. and Eriksson. It applies Gibbs free-energy minimization using an iterative, Lagrangian optimization scheme. Given elemental abundances, TEA calculates molecular abundances for a particular temperature and pressure or a list of temperature–pressure pairs. We tested the code against the method of Burrows & Sharp, the free thermochemical equilibrium code Chemical Equilibrium with Applications (CEA), and the example given by Burrows & Sharp. Using their thermodynamic data, TEA reproduces their final abundances, but with higher precision. We also applied the TEA abundance calculations to models of several hot-Jupiter exoplanets, producing expected results. TEA is written in Python in a modular format. There is a start guide, a user manual, and a code document in addition to this theory paper. TEA is available under a reproducible-research, open-source license via https://github.com/dzesmin/TEA.

  18. Equilibrium gold nanoclusters quenched with biodegradable polymers.

    Science.gov (United States)

    Murthy, Avinash K; Stover, Robert J; Borwankar, Ameya U; Nie, Golay D; Gourisankar, Sai; Truskett, Thomas M; Sokolov, Konstantin V; Johnston, Keith P

    2013-01-22

    Although sub-100 nm nanoclusters of metal nanoparticles are of interest in many fields including biomedical imaging, sensors, and catalysis, it has been challenging to control their morphologies and chemical properties. Herein, a new concept is presented to assemble equilibrium Au nanoclusters of controlled size by tuning the colloidal interactions with a polymeric stabilizer, PLA(1k)-b-PEG(10k)-b-PLA(1k). The nanoclusters form upon mixing a dispersion of ~5 nm Au nanospheres with a polymer solution followed by partial solvent evaporation. A weakly adsorbed polymer quenches the equilibrium nanocluster size and provides steric stabilization. Nanocluster size is tuned from ~20 to ~40 nm by experimentally varying the final Au nanoparticle concentration and the polymer/Au ratio, along with the charge on the initial Au nanoparticle surface. Upon biodegradation of the quencher, the nanoclusters reversibly and fully dissociate to individual ~5 nm primary particles. Equilibrium cluster size is predicted semiquantitatively with a free energy model that balances short-ranged depletion and van der Waals attractions with longer-ranged electrostatic repulsion, as a function of the Au and polymer concentrations. The close spacings of the Au nanoparticles in the clusters produce strong NIR extinction over a broad range of wavelengths from 650 to 900 nm, which is of practical interest in biomedical imaging. PMID:23230905

  19. Interspecies scaling of excretory amounts using allometry - retrospective analysis with rifapentine, aztreonam, carumonam, pefloxacin, miloxacin, trovafloxacin, doripenem, imipenem, cefozopran, ceftazidime, linezolid for urinary excretion and rifapentine, cabotegravir, and dolutegravir for fecal excretion.

    Science.gov (United States)

    Srinivas, Nuggehally R

    2016-09-01

    1. Interspecies allometry scaling for prediction of human excretory amounts in urine or feces was performed for numerous antibacterials. Antibacterials used for urinary scaling were: rifapentine, pefloxacin, trovafloxacin (Gr1/low; 50%). Rifapentine, cabotegravir, and dolutegravir was used for fecal scaling (high; >50%). 2. The employment of allometry equation: Y = aW(b) enabled scaling of urine/fecal amounts from animal species. Corresponding predicted amounts were converted into % recovery by considering the respective human dose. Comparison of predicted/observed values enabled fold difference and error calculations (mean absolute error [MAE] and root mean square error [RMSE]). Comparisons were made for urinary/fecal data; and qualitative assessment was made amongst Gr1/Gr2/Gr3 for urine. 3. Average correlation coefficient for the allometry scaling was >0.995. Excretory amount predictions were largely within 0.75- to 1.5-fold differences. Average MAE and RMSE were within ±22% and 23%, respectively. Although robust predictions were achieved for higher urinary/fecal excretion (>50%), interspecies scaling was applicable for low/medium excretory drugs. 4. Based on the data, interspecies scaling of urine or fecal excretory amounts may be potentially used as a tool to understand the significance of either urinary or fecal routes of elimination in humans in early development. PMID:26711252

  20. Helical axis stellarator equilibrium model

    International Nuclear Information System (INIS)

    An asymptotic model is developed to study MHD equilibria in toroidal systems with a helical magnetic axis. Using a characteristic coordinate system based on the vacuum field lines, the equilibrium problem is reduced to a two-dimensional generalized partial differential equation of the Grad-Shafranov type. A stellarator-expansion free-boundary equilibrium code is modified to solve the helical-axis equations. The expansion model is used to predict the equilibrium properties of Asperators NP-3 and NP-4. Numerically determined flux surfaces, magnetic well, transform, and shear are presented. The equilibria show a toroidal Shafranov shift

  1. Equilibrium with arbitrary market structure

    DEFF Research Database (Denmark)

    Grodal, Birgit; Vind, Karl

    2005-01-01

    complete market predicted by this theory is clearly unrealistic, and Radner [10] formulated and proved existence of equilibrium in a multiperiod model with incomplete markets. In this paper the Radner result is extended. Radner assumed a specific structure of markets, independence of preferences......Fifty years ago Arrow [1] introduced contingent commodities and Debreu [4] observed that this reinterpretation of a commodity was enough to apply the existing general equilibrium theory to uncertainty and time. This interpretation of general equilibrium theory is the Arrow-Debreu model. The...

  2. Dissolved and labile concentrations of Cd, Cu, Pb, and Zn in the South Fork Coeur d'Alene River, Idaho: Comparisons among chemical equilibrium models and implications for biotic ligand models

    Science.gov (United States)

    Balistrieri, L.S.; Blank, R.G.

    2008-01-01

    In order to evaluate thermodynamic speciation calculations inherent in biotic ligand models, the speciation of dissolved Cd, Cu, Pb, and Zn in aquatic systems influenced by historical mining activities is examined using equilibrium computer models and the diffusive gradients in thin films (DGT) technique. Several metal/organic-matter complexation models, including WHAM VI, NICA-Donnan, and Stockholm Humic model (SHM), are used in combination with inorganic speciation models to calculate the thermodynamic speciation of dissolved metals and concentrations of metal associated with biotic ligands (e.g., fish gills). Maximum dynamic metal concentrations, determined from total dissolved metal concentrations and thermodynamic speciation calculations, are compared with labile metal concentrations measured by DGT to assess which metal/organic-matter complexation model best describes metal speciation and, thereby, biotic ligand speciation, in the studied systems. Results indicate that the choice of model that defines metal/organic-matter interactions does not affect calculated concentrations of Cd and Zn associated with biotic ligands for geochemical conditions in the study area, whereas concentrations of Cu and Pb associated with biotic ligands depend on whether the speciation calculations use WHAM VI, NICA-Donnan, or SHM. Agreement between labile metal concentrations and dynamic metal concentrations occurs when WHAM VI is used to calculate Cu speciation and SHM is used to calculate Pb speciation. Additional work in systems that contain wide ranges in concentrations of multiple metals should incorporate analytical speciation methods, such as DGT, to constrain the speciation component of biotic ligand models. ?? 2008 Elsevier Ltd.

  3. On Generalized Vector Equilibrium Problems

    Institute of Scientific and Technical Information of China (English)

    An-hua Wan; Jun-yi Fu; Wei-hua Mao

    2006-01-01

    A new generalized vector equilibrium problem involving set-valued mappings and the proper quasi-concavity of set-valued mappings in topological vector spaces are introduced; its existence theorems and the convexity of the solution sets are established.

  4. On the local equilibrium condition

    International Nuclear Information System (INIS)

    A physical system is in local equilibrium if it cannot be distinguished from a global equilibrium by ''infinitesimally localized measurements''. This should be a natural characterization of local equilibrium, but the problem is to give a precise meaning to the qualitative phrase ''infinitesimally localized measurements''. A solution is suggested in form of a Local Equilibrium Condition (LEC), which can be applied to linear relativistic quantum field theories but not directly to selfinteracting quantum fields. The concept of local temperature resulting from LEC is compared to an old approach to local temperature based on the principle of maximal entropy. It is shown that the principle of maximal entropy does not always lead to physical states if it is applied to relativistic quantum field theories. (orig.)

  5. Equilibrium Electro-osmotic Instability

    CERN Document Server

    Rubinstein, Isaak

    2014-01-01

    Since its prediction fifteen years ago, electro-osmotic instability has been attributed to non-equilibrium electro-osmosis related to the extended space charge which develops at the limiting current in the course of concentration polarization at a charge-selective interface. This attribution had a double basis. Firstly, it has been recognized that equilibrium electro-osmosis cannot yield instability for a perfectly charge-selective solid. Secondly, it has been shown that non-equilibrium electro-osmosis can. First theoretical studies in which electro-osmotic instability was predicted and analyzed employed the assumption of perfect charge-selectivity for the sake of simplicity and so did the subsequent numerical studies of various time-dependent and nonlinear features of electro-osmotic instability. In this letter, we show that relaxing the assumption of perfect charge-selectivity (tantamount to fixing the electrochemical potential in the solid) allows for equilibrium electro-osmotic instability. Moreover, we s...

  6. Equilibrium Distribution of Labor Productivity

    OpenAIRE

    Aoyama, Hideaki; Iyetomi, Hiroshi; Yoshikawa, Hiroshi

    2012-01-01

    We construct a theoretical model for equilibrium distribution of workers across sectors with different labor productivity, assuming that a sector can accommodate a limited number of workers which depends only on its productivity. A general formula for such distribution of productivity is obtained, using the detail-balance condition necessary for equilibrium in the Ehrenfest-Brillouin model. We also carry out an empirical analysis on the average number of workers in given productivity sectors ...

  7. Conformity, Equity and Correlated Equilibrium

    OpenAIRE

    Edward Cartwright; Myrna Wooders

    2008-01-01

    We explore the potential for correlated equilibrium to capture conformity to norms and the coordination of behavior within social groups. Given a partition of players into social groups we propose three properties one may expect of a correlated equilibrium: within-group anonymity, group independence and stereotyped beliefs. Within-group anonymity requires that players within the same social group have equal opportunities and equal payoffs. Group independence requires that there be no correlat...

  8. Equilibrium wage-tenure contracts

    OpenAIRE

    Burdett, K.; Coles, Melvin G.

    2003-01-01

    In this study we consider a labor market matching model where firms post wage-tenure contracts and workers, both employed and unemployed, search for new job opportunities. Given workers are risk averse, we establish there is a unique equilibrium in the environment considered. Although firms in the market make different offers in equilibrium, all post a wage-tenure contract that implies a worker's wage increases smoothly with tenure at the firm. As firms make different offers, there is job tur...

  9. The Alternative to Equilibrium Existence

    OpenAIRE

    David Rahman

    2008-01-01

    This paper establishes and interprets a necessary and sucient condition for existence of (countably additive) correlated equilibrium in n-person games, assuming only that utility functions are bounded, measurable. A sequence of deviation profiles is consistent if there exists a correlated strategy that makes every profile in the sequence unprofitable with respect to the sum of utilities. An equilibrium exists if and only if every sequence of deviation profiles has a consistent subsequence. Th...

  10. Generalized Market Equilibrium: "Stable" CAPM

    OpenAIRE

    Belkacem, Lotfi; Lévy Véhel, Jacques; Walter, Christian

    1995-01-01

    Our main purpose in this paper is to derive the generalized equilibrium relationship between risk and return under the assumption that the asset returns follow a joint symmetric stable distribution. We show that equilibrium rates of return on all risky assets are functions of their covariation with the market portfolio. The "stable" CAPM highlights a new measure of the quantity of risk which may be interpreted as a "generalized beta coefficient".

  11. A Communication Proof Equilibrium Concept

    OpenAIRE

    Ferreira, José Luis

    1996-01-01

    This paper proposes an equilibrium concept for the classes of environments in which players can cornmunicate with each other but cannot rnake binding agreernents. This Cornmunication-proof equilibrium is intended to be regarded as an extension of both Coalition and Renegotiation-proof equilibria. Conceptual foundations for this particular definition are widely discussed as it is confronted with other definitions in this class of environments. The definition is extended to in...

  12. Multicomponent Equilibrium Models for Testing Geothermometry Approaches

    Energy Technology Data Exchange (ETDEWEB)

    Carl D. Palmer; Robert W. Smith; Travis L. McLing

    2013-02-01

    Geothermometry is an important tool for estimating deep reservoir temperature from the geochemical composition of shallower and cooler waters. The underlying assumption of geothermometry is that the waters collected from shallow wells and seeps maintain a chemical signature that reflects equilibrium in the deeper reservoir. Many of the geothermometers used in practice are based on correlation between water temperatures and composition or using thermodynamic calculations based a subset (typically silica, cations or cation ratios) of the dissolved constituents. An alternative approach is to use complete water compositions and equilibrium geochemical modeling to calculate the degree of disequilibrium (saturation index) for large number of potential reservoir minerals as a function of temperature. We have constructed several “forward” geochemical models using The Geochemist’s Workbench to simulate the change in chemical composition of reservoir fluids as they migrate toward the surface. These models explicitly account for the formation (mass and composition) of a steam phase and equilibrium partitioning of volatile components (e.g., CO2, H2S, and H2) into the steam as a result of pressure decreases associated with upward fluid migration from depth. We use the synthetic data generated from these simulations to determine the advantages and limitations of various geothermometry and optimization approaches for estimating the likely conditions (e.g., temperature, pCO2) to which the water was exposed in the deep subsurface. We demonstrate the magnitude of errors that can result from boiling, loss of volatiles, and analytical error from sampling and instrumental analysis. The estimated reservoir temperatures for these scenarios are also compared to conventional geothermometers. These results can help improve estimation of geothermal resource temperature during exploration and early development.

  13. The prediction of mineral solubilities in natural waters: A chemical equilibrium model for the NaKCaMgClSO 4H 2O system at temperatures below 25°C

    Science.gov (United States)

    Spencer, Ronald J.; Møller, Nancy; Weare, John H.

    1990-03-01

    A low temperature thermochemical model for the system NaKCaMgClSO 4H 2O is presented. Aqueous species and standard chemical potentials of solid-solution reactions are modeled from published data for binary and ternary solutions. The temperature range below 25°C (to near -60°C) is emphasized, although the model parameters are fitted to merge smoothly with those of higher temperature models at temperatures between 25 and 100°C. Binary and ternary specific ion interaction terms vary independently with temperature and are modeled using freezing point depression and mineral solubility measurements. The standard chemical potential of the ice-water reaction is fitted independent of the model (from vapor pressure and free energy data). Remaining standard chemical potentials of solidsolution reactions are fitted along with the specific ion interaction terms. Model predictions are tested against published data for minerals formed and brine compositions obtained by chilling seawater to the eutectic (about -54°C). The model predicts the sequence of solid phases observed to precipitate from chilled seawater (mice-mirabilite-hydrohalite-sylvite-MgCl 2 · 12H 2Oantarcticite). For all but mirabilite model temperatures are within the uncertainty of the measured temperature. The compositions of brines predicted by the model also closely follow the observed compositions. The model allows accurate predictions of the freezing points of simple and complex solutions in the system. Low temperature phase equilibria and mineral solubilities may also be predicted. The model may be used to determine the composition of brines in fluid inclusions in the multicomponent system based on low temperature phase equilibria.

  14. Shape characteristics of equilibrium and non-equilibrium fractal clusters

    Science.gov (United States)

    Mansfield, Marc L.; Douglas, Jack F.

    2013-07-01

    It is often difficult in practice to discriminate between equilibrium and non-equilibrium nanoparticle or colloidal-particle clusters that form through aggregation in gas or solution phases. Scattering studies often permit the determination of an apparent fractal dimension, but both equilibrium and non-equilibrium clusters in three dimensions frequently have fractal dimensions near 2, so that it is often not possible to discriminate on the basis of this geometrical property. A survey of the anisotropy of a wide variety of polymeric structures (linear and ring random and self-avoiding random walks, percolation clusters, lattice animals, diffusion-limited aggregates, and Eden clusters) based on the principal components of both the radius of gyration and electric polarizability tensor indicates, perhaps counter-intuitively, that self-similar equilibrium clusters tend to be intrinsically anisotropic at all sizes, while non-equilibrium processes such as diffusion-limited aggregation or Eden growth tend to be isotropic in the large-mass limit, providing a potential means of discriminating these clusters experimentally if anisotropy could be determined along with the fractal dimension. Equilibrium polymer structures, such as flexible polymer chains, are normally self-similar due to the existence of only a single relevant length scale, and are thus anisotropic at all length scales, while non-equilibrium polymer structures that grow irreversibly in time eventually become isotropic if there is no difference in the average growth rates in different directions. There is apparently no proof of these general trends and little theoretical insight into what controls the universal anisotropy in equilibrium polymer structures of various kinds. This is an obvious topic of theoretical investigation, as well as a matter of practical interest. To address this general problem, we consider two experimentally accessible ratios, one between the hydrodynamic and gyration radii, the other

  15. Quantum Statistical Mechanics. III. Equilibrium Probability

    OpenAIRE

    Attard, Phil

    2014-01-01

    Given are a first principles derivation and formulation of the probabilistic concepts that underly equilibrium quantum statistical mechanics. The transition to non-equilibrium probability is traversed briefly.

  16. Spacecraft Sterilization Using Non-Equilibrium Atmospheric Pressure Plasma

    Science.gov (United States)

    Cooper, Moogega; Vaze, Nachiket; Anderson, Shawn; Fridman, Gregory; Vasilets, Victor N.; Gutsol, Alexander; Tsapin, Alexander; Fridman, Alexander

    2007-01-01

    As a solution to chemically and thermally destructive sterilization methods currently used for spacecraft, non-equilibrium atmospheric pressure plasmas are used to treat surfaces inoculated with Bacillus subtilis and Deinococcus radiodurans. Evidence of significant morphological changes and reduction in viability due to plasma exposure will be presented, including a 4-log reduction of B. subtilis after 2 minutes of dielectric barrier discharge treatment.

  17. A Unified Kinetics and Equilibrium Experiment: Rate Law, Activation Energy, and Equilibrium Constant for the Dissociation of Ferroin

    Science.gov (United States)

    Sattar, Simeen

    2011-01-01

    Tris(1,10-phenanthroline)iron(II) is the basis of a suite of four experiments spanning 5 weeks. Students determine the rate law, activation energy, and equilibrium constant for the dissociation of the complex ion in acid solution and base dissociation constant for phenanthroline. The focus on one chemical system simplifies a daunting set of…

  18. Physicochemical Perturbations of Phase Equilibriums

    CERN Document Server

    Dobruskin, Vladimir Kh

    2010-01-01

    The alternative approach to the displacement of gas/liquid equilibrium is developed on the basis of the Clapeyron equation. The phase transition in the system with well-established properties is taken as a reference process to search for the parameters of phase transition in the perturbed equilibrium system. The main equation, derived in the framework of both classical thermodynamics and statistical mechanics, establishes a correlation between variations of enthalpies of evaporation, \\Delta (\\Delta H), which is induced by perturbations, and the equilibrium vapor pressures. The dissolution of a solute, changing the surface shape, and the effect of the external field of adsorbents are considered as the perturbing actions on the liquid phase. The model provides the unified method for studying (1) solutions, (2) membrane separations (3) surface phenomena, and (4) effect of the adsorption field; it leads to the useful relations between \\Delta (\\Delta H), on the one hand, and the osmotic pressures, the Donnan poten...

  19. Equilibrium in a Production Economy

    Energy Technology Data Exchange (ETDEWEB)

    Chiarolla, Maria B., E-mail: maria.chiarolla@uniroma1.it [Universita di Roma ' La Sapienza' , Dipartimento di Metodi e Modelli per l' Economia, il Territorio e la Finanza, Facolta di Economia (Italy); Haussmann, Ulrich G., E-mail: uhaus@math.ubc.ca [University of British Columbia, Department of Mathematics (Canada)

    2011-06-15

    Consider a closed production-consumption economy with multiple agents and multiple resources. The resources are used to produce the consumption good. The agents derive utility from holding resources as well as consuming the good produced. They aim to maximize their utility while the manager of the production facility aims to maximize profits. With the aid of a representative agent (who has a multivariable utility function) it is shown that an Arrow-Debreu equilibrium exists. In so doing we establish technical results that will be used to solve the stochastic dynamic problem (a case with infinite dimensional commodity space so the General Equilibrium Theory does not apply) elsewhere.

  20. Equilibrium in a Production Economy

    International Nuclear Information System (INIS)

    Consider a closed production-consumption economy with multiple agents and multiple resources. The resources are used to produce the consumption good. The agents derive utility from holding resources as well as consuming the good produced. They aim to maximize their utility while the manager of the production facility aims to maximize profits. With the aid of a representative agent (who has a multivariable utility function) it is shown that an Arrow-Debreu equilibrium exists. In so doing we establish technical results that will be used to solve the stochastic dynamic problem (a case with infinite dimensional commodity space so the General Equilibrium Theory does not apply) elsewhere.

  1. Torsatron equilibrium and stability studies

    International Nuclear Information System (INIS)

    Equilibrium and stability results are presented for the Advanced Toroidal Facility (ATF) device. The results of three-dimensional equilibrium calculations and free boundary average method calculations are shown to be in good agreement with previous fixed boundary average method results. These favorable comparisons serve as a valuable validation of the simple and computationally efficient fixed boundary average method. Stability calculations for the free boundary average method equilibria are also in good agreement with fixed boundary calculations, showing instability only when the plasma is shifted inward with an applied vertical field

  2. Methane on Mars: Thermodynamic Equilibrium and Photochemical Calculations

    Science.gov (United States)

    Levine, J. S.; Summers, M. E.; Ewell, M.

    2010-01-01

    The detection of methane (CH4) in the atmosphere of Mars by Mars Express and Earth-based spectroscopy is very surprising, very puzzling, and very intriguing. On Earth, about 90% of atmospheric ozone is produced by living systems. A major question concerning methane on Mars is its origin - biological or geological. Thermodynamic equilibrium calculations indicated that methane cannot be produced by atmospheric chemical/photochemical reactions. Thermodynamic equilibrium calculations for three gases, methane, ammonia (NH3) and nitrous oxide (N2O) in the Earth s atmosphere are summarized in Table 1. The calculations indicate that these three gases should not exist in the Earth s atmosphere. Yet they do, with methane, ammonia and nitrous oxide enhanced 139, 50 and 12 orders of magnitude above their calculated thermodynamic equilibrium concentration due to the impact of life! Thermodynamic equilibrium calculations have been performed for the same three gases in the atmosphere of Mars based on the assumed composition of the Mars atmosphere shown in Table 2. The calculated thermodynamic equilibrium concentrations of the same three gases in the atmosphere of Mars is shown in Table 3. Clearly, based on thermodynamic equilibrium calculations, methane should not be present in the atmosphere of Mars, but it is in concentrations approaching 30 ppbv from three distinct regions on Mars.

  3. Non-Stationary Search Equilibrium

    OpenAIRE

    Fabien Postel-Vinay; Giuseppe Moscarini

    2009-01-01

    We study aggregate equilibrium dynamics of a frictional labor market where firms post employment contracts and workers search randomly on and off the job for such contracts, while the economy is hit by aggregate productivity shocks. Our exercise provides the first analysis of aggregate dynamics of a popular class of search wage-posting models with undirected job search.

  4. Incentives in Supply Function Equilibrium

    DEFF Research Database (Denmark)

    Vetter, Henrik

    2014-01-01

    The author analyses delegation in homogenous duopoly under the assumption that the firm-managers compete in supply functions. In supply function equilibrium, managers’ decisions are strategic complements. This reverses earlier findings in that the author finds that owners give managers incentives...

  5. Financial equilibrium with career concerns

    Directory of Open Access Journals (Sweden)

    Amil Dasgupta

    2006-03-01

    Full Text Available What are the equilibrium features of a financial market where a sizeable proportion of traders face reputational concerns? This question is central to our understanding of financial markets, which are increasingly dominated by institutional investors. We construct a model of delegated portfolio management that captures key features of the US mutual fund industry and embed it in an asset pricing framework. We thus provide a formal model of financial equilibrium with career concerned agents. Fund managers differ in their ability to understand market fundamentals, and in every period investors choose a fund. In equilibrium, the presence of career concerns induces uninformed fund managers to churn, i.e., to engage in trading even when they face a negative expected return. Churners act as noise traders and enhance the level of trading volume. The equilibrium relationship between fund return and net fund flows displays a skewed shape that is consistent with stylized facts. The robustness of our core results is probed from several angles.

  6. Critical evaluation of some equilibrium constants involving organophosphorus extractants

    CERN Document Server

    Marcus, Y

    2013-01-01

    Critical Evaluation of Some Equilibrium Constants Involving Organophosphorus Extractants is a supplementary text to the compilation ""Equilibrium Constants of Liquid-Liquid Distribution Reactions (Introduction, and Part I: Organophosphorus Extractants).The book contains a number of well documented chemical reactions that are critically evaluated. The reactions evaluated comprise those from List 1 for which data are available. There are, however, a great variety of reactions that cannot be critically evaluated due to lack of experimental data and unverifiable results.Chemists will find this com

  7. The concept of equilibrium in organization theory

    OpenAIRE

    Gazendam, Henk W.M.

    1997-01-01

    Many organization theories consist of an interpretation frame and an idea about the ideal equilibrium state. This article explains how the equilibrium concept is used in four organization theories: the theories of Fayol, Mintzberg, Morgan, and Volberda. Equilibrium can be defined as balance, fit or requisite variety. Equilibrium is related to observables dependent on the definition of organization as work organization, formal organization or artifact organization. Equilibrium can be explicitl...

  8. The equilibrium crystal shape of nickel

    International Nuclear Information System (INIS)

    Highlights: → The ECS of pure Ni is completely facetted with both dense and high-index planes. → The partial pressure of oxygen has a significant effect on the surface anisotropy. → The addition of Fe decreased the anisotropy and de-stabilized high-index planes. → During solid dewetting nucleation barriers prevent equilibration of the top facet. - Abstract: The crystal shape of Ni particles, dewetted in the solid state on sapphire substrates, was examined as a function of the partial pressure of oxygen (P(O2)) and iron content using scanning and transmission electron microscopy. The chemical composition of the surface was characterized by atom-probe tomography. Unlike other face-centered cubic (fcc) equilibrium crystal shapes, the Ni crystals containing little or no impurities exhibited a faceted shape, indicating large surface anisotropy. In addition to the {1 1 1}, {1 0 0} and {1 1 0} facets, which are usually present in the equilibrium crystal shape of fcc metals, high-index facets were identified such as {1 3 5} and {1 3 8} at low P(O2), and {0 1 2} and {0 1 3} at higher P(O2). The presence of iron altered the crystal shape into a truncated sphere with only facets parallel to denser planes. The issue of particle equilibration is discussed specifically for the case of solid-state dewetting.

  9. Chemical cosmology

    CERN Document Server

    Boeyens, Jan CA

    2010-01-01

    The composition of the most remote objects brought into view by the Hubble telescope can no longer be reconciled with the nucleogenesis of standard cosmology and the alternative explanation, in terms of the LAMBDA-Cold-Dark-Matter model, has no recognizable chemical basis. A more rational scheme, based on the chemistry and periodicity of atomic matter, opens up an exciting new interpretation of the cosmos in terms of projective geometry and general relativity. The response of atomic structure to environmental pressure predicts non-Doppler cosmical redshifts and equilibrium nucleogenesis by alp

  10. Evaluating equilibrium and non-equilibrium transport of bromide and isoproturon in disturbed and undisturbed soil columns.

    Science.gov (United States)

    Dousset, S; Thevenot, M; Pot, V; Simunek, J; Andreux, F

    2007-12-01

    In this study, displacement experiments of isoproturon were conducted in disturbed and undisturbed columns of a silty clay loam soil under similar rainfall intensities. Solute transport occurred under saturated conditions in the undisturbed soil and under unsaturated conditions in the sieved soil because of a greater bulk density of the compacted undisturbed soil compared to the sieved soil. The objective of this work was to determine transport characteristics of isoproturon relative to bromide tracer. Triplicate column experiments were performed with sieved (structure partially destroyed to simulate conventional tillage) and undisturbed (structure preserved) soils. Bromide experimental breakthrough curves were analyzed using convective-dispersive and dual-permeability (DP) models (HYDRUS-1D). Isoproturon breakthrough curves (BTCs) were analyzed using the DP model that considered either chemical equilibrium or non-equilibrium transport. The DP model described the bromide elution curves of the sieved soil columns well, whereas it overestimated the tailing of the bromide BTCs of the undisturbed soil columns. A higher degree of physical non-equilibrium was found in the undisturbed soil, where 56% of total water was contained in the slow-flow matrix, compared to 26% in the sieved soil. Isoproturon BTCs were best described in both sieved and undisturbed soil columns using the DP model combined with the chemical non-equilibrium. Higher degradation rates were obtained in the transport experiments than in batch studies, for both soils. This was likely caused by hysteresis in sorption of isoproturon. However, it cannot be ruled out that higher degradation rates were due, at least in part, to the adopted first-order model. Results showed that for similar rainfall intensity, physical and chemical non-equilibrium were greater in the saturated undisturbed soil than in the unsaturated sieved soil. Results also suggested faster transport of isoproturon in the undisturbed soil due

  11. Competitive equilibrium with search frictions : a general equilibrium approach

    OpenAIRE

    Jerez, Belén

    2012-01-01

    When the trading process is characterized by search frictions, traders may be rationed so markets need not clear. We build a general equilibrium model with transferable utility where the uncertainty arising from rationing is incorporated in the definition of a commodity, in the spirit of the Arrow-Debreu theory. Prices of commodities then depend not only on their physical characteristics, but also on the probability that their trade is rationed. The standard definition of competitive equilibr...

  12. Non-Equilibrium Properties from Equilibrium Free Energy Calculations

    Science.gov (United States)

    Pohorille, Andrew; Wilson, Michael A.

    2012-01-01

    Calculating free energy in computer simulations is of central importance in statistical mechanics of condensed media and its applications to chemistry and biology not only because it is the most comprehensive and informative quantity that characterizes the eqUilibrium state, but also because it often provides an efficient route to access dynamic and kinetic properties of a system. Most of applications of equilibrium free energy calculations to non-equilibrium processes rely on a description in which a molecule or an ion diffuses in the potential of mean force. In general case this description is a simplification, but it might be satisfactorily accurate in many instances of practical interest. This hypothesis has been tested in the example of the electrodiffusion equation . Conductance of model ion channels has been calculated directly through counting the number of ion crossing events observed during long molecular dynamics simulations and has been compared with the conductance obtained from solving the generalized Nernst-Plank equation. It has been shown that under relatively modest conditions the agreement between these two approaches is excellent, thus demonstrating the assumptions underlying the diffusion equation are fulfilled. Under these conditions the electrodiffusion equation provides an efficient approach to calculating the full voltage-current dependence routinely measured in electrophysiological experiments.

  13. On the geometry and allometry of big-buttressed trees - a challenge for forest monitoring: new insights from 3D-modeling with terrestrial laser scanning

    Directory of Open Access Journals (Sweden)

    Nölke N

    2015-10-01

    Full Text Available In many old-growth natural and close-to-natural forest types, notably in humid tropical forests, a relatively small number of very tall trees contribute considerably to stand basal area and biomass. Such trees often show distinct buttress roots with irregular non-convex shapes. Buttresses are complex structures in the lowest stem section, where most tree biomass is located. The methods used to assess the diameter of buttressed trees have a large impact on the determination of volume and biomass, as well as on the resulting estimates of the aboveground carbon stock in tropical forests. As the measurement of diameter at breast height (DBH at 1.3 m is not feasible in such conditions, the diameter above buttress (DAB, where the cylindrical bole of the tree begins, is usually measured and included as an independent variable in biomass models. We conducted a methodological study aimed at determining the volume and biomass of individual buttressed trees belonging to several tropical species by the application of terrestrial laser scanning (TLS. The geometry and allometry of the buttresses, as well as the change with height along the stem in buttress volume and cross-sectional area were analyzed. Our results suggest that the relationship between cross-sectional areas at DAB height (ADAB and the actual tree basal area measured at 1.3 m height is relatively strong (R² = 0.87 across a range of different species, buttress morphologies and tree dimensions. Furthermore, the change in stem cross-sectional area with tree height was surprisingly similar and smooth. Despite the small number of trees sampled, the methodological approach used in this study provided new insights on the very irregular geometry of buttressed trees. Our results may help improving the volume and biomass models for buttressed trees, that are crucial contributors to carbon stocks in tropical forests.

  14. Neutrino Emissivity of Non-equilibrium beta processes With Nucleon Superfluidity

    OpenAIRE

    Pi, Chun-Mei; Zheng, Xiao-Ping; Yang, Shu-Hua

    2009-01-01

    We investigate the influence of nucleon superfluidity on the neutrino emissivity of non-equilibrium beta processes. Calculations are performed of the reduction factors for direct and modified Urca processes with three types of nucleon superfluidity in $npe$ matter. The numerical results are given since the analytical solution is impossible. We find that the behavior of the superfluid influence is closely related to the chemical departure from beta equilibrium. For small chemical departure, th...

  15. Measurement of vapor-liquid-liquid phase equilibrium-Equipment and results

    DEFF Research Database (Denmark)

    Frost, Michael Grynnerup; von Solms, Nicolas; Richon, Dominique;

    2015-01-01

    -water-gas hydrate inhibitor systems, at temperatures ranging from 283 to 353 K and at pressures up to 40 MPa. The core of the equipment is an equilibrium cell, equipped with sapphire windows and connected to an analytical system by capillary samplers.New vapor-liquid-liquid equilibrium data are reported for methane...... optimization is dependent on phase equilibrium data.The objective of this work is to provide experimental data for hydrocarbon systems with polar chemicals such as alcohols, glycols and water. A new experimental equipment was designed and constructed for measurement of multi-phase equilibrium in hydrocarbon...

  16. TEA: A Code for Calculating Thermochemical Equilibrium Abundances

    CERN Document Server

    Blecic, Jasmina; Bowman, M Oliver

    2015-01-01

    We present an open-source Thermochemical Equilibrium Abundances (TEA) code that calculates the abundances of gaseous molecular species. The code is based on the methodology of White et al. (1958) and Eriksson (1971). It applies Gibbs free-energy minimization using an iterative, Lagrangian optimization scheme. Given elemental abundances, TEA calculates molecular abundances for a particular temperature and pressure or a list of temperature-pressure pairs. We tested the code against the method of Burrows & Sharp (1999), the free thermochemical equilibrium code CEA (Chemical Equilibrium with Applications), and the example given by White et al. (1958). Using their thermodynamic data, TEA reproduces their final abundances, but with higher precision. We also applied the TEA abundance calculations to models of several hot-Jupiter exoplanets, producing expected results. TEA is written in Python in a modular format. There is a start guide, a user manual, and a code document in addition to this theory paper. TEA is ...

  17. Protonation Equilibrium of Linear Homopolyacids

    Directory of Open Access Journals (Sweden)

    Požar J.

    2015-07-01

    Full Text Available The paper presents a short summary of investigations dealing with protonation equilibrium of linear homopolyacids, in particularly those of high charge density. Apart from the review of experimental results which can be found in the literature, a brief description of theoretical models used in processing the dependence of protonation constants on monomer dissociation degree and ionic strength is given (cylindrical model based on Poisson-Boltzmann equation, cylindrical Stern model, the models according to Ising, Högfeldt, Mandel and Katchalsky. The applicability of these models regarding the polyion charge density, electrolyte concentration and counterion type is discussed. The results of Monte Carlo simulations of protonation equilibrium are also briefly mentioned. In addition, frequently encountered errors connected with calibration of of glass electrode and the related unreliability of determined protonation constants are pointed out.

  18. Thermal Equilibrium Calorimeters -- An Introduction

    CERN Document Server

    McCammon, D

    2005-01-01

    Near-equilibrium thermal detectors operate as classical calorimeters, with energy deposition and internal equilibration times short compared to the thermal time constant of the device. Advances in fabrication techniques, cryogenics, and electronics have made it practical to measure deposited energy with unprecedented sensitivity and precision. In this chapter we discuss performance considerations for these devices, including optimal filtering and energy resolution calculations. We begin with the basic theory of simple equilibrium calorimeters with ideal resistive thermometers. This provides a starting point for a brief discussion of electrothermal feedback, other noise sources, various non-ideal effects, and nonlinearity. We then describe other types of thermometers and show how they fit into this theoretical framework and why they may require different optimizations and figures of merit. Most of this discussion is applicable also to power detectors, or bolometers, where the detector time constants may be sho...

  19. Equilibrium Corporate Finance and Intermediation

    OpenAIRE

    Bisin, Alberto; Gottardi, Piero; Ruta, Guido

    2014-01-01

    This paper analyzes a class of competitive economies with production, incomplete financial markets, and agency frictions. Firms take their production, financing, and contractual decisions so as to maximize their value under rational conjectures. We show that competitive equilibria exist and that shareholders always unanimously support firms' choices. In addition, equilibrium allocations have well-defined welfare properties: they are constrained efficient when information is symmetric, or when...

  20. Essays on equilibrium policy analysis.

    OpenAIRE

    Gallipoli, G.

    2007-01-01

    This thesis describes and implements a method to carry out policy analysis within an equilibrium framework. This method allows to account for potential effects induced by price adjustments. The analysis is based on overlapping generation, life-cycle models where heterogeneous agents make endogenous decisions regarding their consumption and education as well as labour supply and criminal activity. Some of the agent's optimising decisions (education, crime) are discrete choices. The first part ...

  1. Holding Costs and Equilibrium Arbitrage

    OpenAIRE

    Tuckman, Bruce; Vila, Jean-Luc.

    1993-01-01

    This paper constructs a dynamic model of the equilibrium determination of relative prices when arbitragers face holding costs. The major findings are that 1) models based on riskless arbitrage arguments alone may not provide usefully tight bounds on observed prices, 2) arbitragers are often most effective in eliminating the mispricings of shorter-term assets, 3) arbitrage activity increases the mean reversion of changes in the mispricing process and reduces their conditional volatility, and 4...

  2. Credit segmentation in general equilibrium

    OpenAIRE

    Cea-Echenique, Sebastián; Torres-Martínez, Juan Pablo

    2015-01-01

    We build a general equilibrium model with endogenous borrowing constraints compatible with credit segmentation. There are personalized trading restrictions connecting prices with both portfolio constraints and consumption possibilities, a setting which has not thoroughly been addressed by the literature. Our approach is general enough to be compatible with incomplete market economies where there exist wealth-dependent and/or investment-dependent credit access, borrowing constraints precluding...

  3. On Equilibrium in Monopolistic Competition

    OpenAIRE

    Richard Carson

    2006-01-01

    The price, output, and quality of a monopolistic competitor are determined by maximizing the difference between its revenue and its cost, where cost is measured exclusive of the rent on its product-specialized inputs. It can be argued that such a firm must have unique inputs that are specialized to its unique product—since product differentiation is otherwise compatible with perfect competition—and the uniqueness of these inputs allows them to earn positive rent, even in long-run equilibrium....

  4. Credit Risk in General Equilibrium

    OpenAIRE

    Eichberger, Jürgen; Rheinberger, Klaus; Summer, Martin

    2011-01-01

    Credit risk models used in quantitative risk management treat credit risk analysis conceptually like a single person decision problem. From this perspective an exogenous source of risk drives the fundamental parameters of credit risk: probability of default, exposure at default and the recovery rate. In reality these parameters are the result of the interaction of many market participants: They are endogenous. We develop a general equilibrium model with endogenous credit risk that can be view...

  5. Internal Labor Markets in Equilibrium

    OpenAIRE

    Timothy N. Bond

    2011-01-01

    Traditional models of promotion have difficulty explaining why many firms do not favor internal employees for advancement. I develop a new model to explain this phenomenon. My model generates an equilibrium where some, but not all, ex ante identical firms recruit strictly internally. These firms employ higher quality entry-level workers, since they hire supervisors exclusively from their lower ranks. The scarcity of high-quality workers limits the use of this strategy. I derive several testab...

  6. Essays on equilibrium unemployment dynamics

    OpenAIRE

    Speigner, Bradley James

    2012-01-01

    This thesis is a collection of three essays in which the behaviour of unemployment is studied in different dynamic environments. Throughout, unemployment is understood to be involuntary, arising due to the uncoordinated nature of trade in the labour market as viewed from the perspective of the Diamond-Mortensen-Pissarides equilibrium matching model. It goes without saying that the fundamental motivation for pursuing this line of research is provided by the untold consequences, bot...

  7. An introduction to equilibrium thermodynamics

    CERN Document Server

    Morrill, Bernard; Hartnett, James P; Hughes, William F

    1973-01-01

    An Introduction to Equilibrium Thermodynamics discusses classical thermodynamics and irreversible thermodynamics. It introduces the laws of thermodynamics and the connection between statistical concepts and observable macroscopic properties of a thermodynamic system. Chapter 1 discusses the first law of thermodynamics while Chapters 2 through 4 deal with statistical concepts. The succeeding chapters describe the link between entropy and the reversible heat process concept of entropy; the second law of thermodynamics; Legendre transformations and Jacobian algebra. Finally, Chapter 10 provides a

  8. Residential Segregation in General Equilibrium

    OpenAIRE

    Bayer, Patrick; McMillan, Robert; Rueben, Kim

    2005-01-01

    This paper studies the causes and consequences of racial segregation using a new general equilibrium model that treats neighborhood compositions as endogenous. The model is estimated using unusually detailed restricted Census microdata covering the entire San Francisco Bay Area, and in combination with a rich array of econometric estimates, serves as a powerful tool for carrying out counterfactual simulations that shed light on the causes and consequences of segregation. In terms of causes, a...

  9. Inventories in dynamic general equilibrium

    OpenAIRE

    Shibayama, Katsuyuki

    2010-01-01

    This article investigates a dynamic general equilibrium model with a stockout constraint, which means that no seller can sell more than the inventories that she has. The model successfully explains two inventory facts; (i) inventory investment is procyclical, and (ii) production is more volatile than sales. The key intuition is that, since inventories and demand are complements in generating sales, the optimal level of inventories is increasing in expected demand. Thus, when demand is expecte...

  10. Computational methods for reactive transport modeling: A Gibbs energy minimization approach for multiphase equilibrium calculations

    Science.gov (United States)

    Leal, Allan M. M.; Kulik, Dmitrii A.; Kosakowski, Georg

    2016-02-01

    We present a numerical method for multiphase chemical equilibrium calculations based on a Gibbs energy minimization approach. The method can accurately and efficiently determine the stable phase assemblage at equilibrium independently of the type of phases and species that constitute the chemical system. We have successfully applied our chemical equilibrium algorithm in reactive transport simulations to demonstrate its effective use in computationally intensive applications. We used FEniCS to solve the governing partial differential equations of mass transport in porous media using finite element methods in unstructured meshes. Our equilibrium calculations were benchmarked with GEMS3K, the numerical kernel of the geochemical package GEMS. This allowed us to compare our results with a well-established Gibbs energy minimization algorithm, as well as their performance on every mesh node, at every time step of the transport simulation. The benchmark shows that our novel chemical equilibrium algorithm is accurate, robust, and efficient for reactive transport applications, and it is an improvement over the Gibbs energy minimization algorithm used in GEMS3K. The proposed chemical equilibrium method has been implemented in Reaktoro, a unified framework for modeling chemically reactive systems, which is now used as an alternative numerical kernel of GEMS.

  11. Mesoscopic non-equilibrium thermodynamics

    Directory of Open Access Journals (Sweden)

    Rubi, Jose' Miguel

    2008-02-01

    Full Text Available Basic concepts like energy, heat, and temperature have acquired a precise meaning after the development of thermodynamics. Thermodynamics provides the basis for understanding how heat and work are related and with the general rules that the macroscopic properties of systems at equilibrium follow. Outside equilibrium and away from macroscopic regimes most of those rules cannot be applied directly. In this paper we present recent developments that extend the applicability of thermodynamic concepts deep into mesoscopic and irreversible regimes. We show how the probabilistic interpretation of thermodynamics together with probability conservation laws can be used to obtain kinetic equations describing the evolution of the relevant degrees of freedom. This approach provides a systematic method to obtain the stochastic dynamics of a system directly from the knowledge of its equilibrium properties. A wide variety of situations can be studied in this way, including many that were thought to be out of reach of thermodynamic theories, such as non-linear transport in the presence of potential barriers, activated processes, slow relaxation phenomena, and basic processes in biomolecules, like translocation and stretching.

  12. Vapor-Liquid Equilibrium of Methane with Water and Methanol. Measurements and Modeling

    DEFF Research Database (Denmark)

    Frost, Michael Grynnerup; Karakatsani, Eirini; von Solms, Nicolas;

    2014-01-01

    There is a need for high-quality experimental phase equilibrium data in the petroleum and chemical industries, for example, mixtures of oil and gas with gas hydrate inhibitors (methanol, glycols) and organic acids. This includes a wide range of different systems, which all deal with processes that...... rely on phase equilibrium data for optimization. The objective of this work is to provide experimental data for hydrocarbon systems with polar chemicals such as alcohols, glycols, and water. New vapor-liquid equilibrium data are reported for methane + water, methane + methanol, and methane + methanol...

  13. Phenomenon of life: between equilibrium and non-linearity.

    Science.gov (United States)

    Galimov, E M

    2004-12-01

    A model of ordering applicable to biological evolution is presented. It is shown that a steady state (more precisely approaching to a steady state) system of irreversible processes, under conditions of disproportionation of entropy, produces a lower-entropy product, that is, ordering. The ordering is defined as restricting of degrees of freedom: freedom of motion, interactions etc. The model differs from previous ones in that it relates the ordering to processes running not far from equilibrium, described in the linear field of non-equilibrium thermodynamics. It is shown that a system, which includes adenosine triphosphate (ATP) to adenosine diphosphate (ADP) conversion meets the demands of the physical model: it provides energy maintaining steady state conditions, and hydrolysis of ATP proceeding with consumption of water can be tightly conjugated with the most important reactions of synthesis of organic polymers (peptides, nucleotide chains etc.), which proceed with release of water. For these and other reasons ATP seems to be a key molecule of prebiotic evolution. It is argued that the elementary chemical reaction proceeding under control of an enzyme is not necessarily far from equilibrium. The experimental evidence supporting this idea, is presented. It is based on isotope data. Carbon isotope distribution in biochemical systems reveals regularity, which is inherent to steady state systems of chemical reactions, proceeding not far from equilibrium. In living organisms this feature appears at the statistical level, as many completely irreversible and non-linear processes occur in organisms. However not-far-from-equilibrium reactions are inherent to biochemical systems as a matter of principle. They are reconcilable with biochemical behavior. Extant organisms are highly evolved entities which, however, show in their basis the same features, as the simplest chemical systems must have had been involved in the origin of life. Some consequences following from the

  14. Morphodynamic equilibrium of alluvial estuaries

    Science.gov (United States)

    Tambroni, Nicoletta; Bolla Pittaluga, Michele; Canestrelli, Alberto; Lanzoni, Stefano; Seminara, Giovanni

    2014-05-01

    The evolution of the longitudinal bed profile of an estuary, with given plan-form configuration, subject to given tidal forcing at the mouth and prescribed values of water and sediment supply from the river is investigated numerically. Our main goal is to ascertain whether, starting from some initial condition, the bed evolution tends to reach a unique equilibrium configuration asymptotically in time. Also, we investigate the morphological response of an alluvial estuary to changes in the tidal range and hydrologic forcing (flow and sediment supply). Finally, the solution helps characterizing the transition between the fluvially dominated region and the tidally dominated region of the estuary. All these issues play an important role also in interpreting how the facies changes along the estuary, thus helping to make correct paleo-environmental and sequence-stratigraphic interpretations of sedimentary successions (Dalrymple and Choi, 2007). Results show that the model is able to describe a wide class of settings ranging from tidally dominated estuaries to fluvially dominated estuaries. In the latter case, the solution is found to compare satisfactory with the analytical asymptotic solution recently derived by Seminara et al. (2012), under the hypothesis of fairly 'small' tidal oscillations. Simulations indicate that the system always moves toward an equilibrium configuration in which the net sediment flux in a tidal cycle is constant throughout the estuary and equal to the constant sediment flux discharged from the river. For constant width, the bed equilibrium profile of the estuarine channel is characterized by two distinct regions: a steeper reach seaward, dominated by the tide, and a less steep upstream reach, dominated by the river and characterized by the undisturbed bed slope. Although the latter reach, at equilibrium, is not directly affected by the tidal wave, however starting from an initial uniform stream with the constant 'fluvial' slope, the final

  15. 18F in hot atom chemistry and equilibrium chemical kinetics

    International Nuclear Information System (INIS)

    Superexcited molecules are unusual species that at present can only be investigated using nuclear recoil methods. The thermochemical technique for measuring the excitation energy distributions of superexcited molecules is reviewed and applied to recent studies of CF318F and C2F518F formed from high energy atomic exchange reactions in CF4 and C2F6. The nascent CF318F and C2F518F range in energy from 1.7 to about 45 eV. The average energies of these products range from 15 to 20 eV. The internal excitation that accompanies these reactions is initially localized near the 18F bonding site, and the C2F518F decomposition mechanism is non-statistical. Moderated nuclear recoil experiments yield mechanisms and rates for the reactions of thermal 18F atoms. Under our standard experimental conditions from 3.4 x 104 to 3.4 x 108 labeled product molecules are available for radioassay. This procedure is free from systematic error and the measurements yield exceptional precision and sensitivity because (1) high energy reactions with the thermally active reagents are suppressed. (2) the host environment is rigorously controlled, and (3) the molecular products from many single atom reactions are directly counted. The limitations of this technique are described and results are presented for the reactions of thermal 18F atoms with CH4 and C2H4. (J.P.N.)

  16. Equilibrium Sampling of Persistent and Bioaccumulative Compounds in Soil and Sediment: Comparison of Two Approaches To Determine Equilibrium Partitioning Concentrations in Lipids

    DEFF Research Database (Denmark)

    Mäenpää, Kimmo; Leppänen, Matti T.; Reichenberg, Fredrik; Figueiredo, Kaisa; Mayer, Philipp

    2011-01-01

    The equilibrium sampling in silicone is increasingly applied to measure freely dissolved concentrations and chemical activities within bioaccumulation research of hydrophobic organic chemicals. Two equilibrium methods were applied to PCBcontaminated soil and sediment, and directly calibrated with...... respect to equilibrium partitioning concentrations in lipids (Clipid,partitioning): (i) Solid phase microextraction in the headspace above the sample (HS-SPME) required optimization for its application to PCBs, and it was calibrated above external partitioning standards in olive oil. (ii) Equilibrium...... results of the two methods were in good agreement and thus validated each other. Finally, the coated glass jar method was applied to field sediment containing invertebrates, which lead to Clipid,partitioning thatwereabouttwotimes higher thanmeasuredlipidnormalized concentrations in the organisms...

  17. The Geometry of Finite Equilibrium Datasets

    DEFF Research Database (Denmark)

    Balasko, Yves; Tvede, Mich

    We investigate the geometry of finite datasets defined by equilibrium prices, income distributions, and total resources. We show that the equilibrium condition imposes no restrictions if total resources are collinear, a property that is robust to small perturbations. We also show that the set of...... equilibrium datasets is pathconnected when the equilibrium condition does impose restrictions on datasets, as for example when total resources are widely non collinear....

  18. Accelerating Multiagent Reinforcement Learning by Equilibrium Transfer.

    Science.gov (United States)

    Hu, Yujing; Gao, Yang; An, Bo

    2015-07-01

    An important approach in multiagent reinforcement learning (MARL) is equilibrium-based MARL, which adopts equilibrium solution concepts in game theory and requires agents to play equilibrium strategies at each state. However, most existing equilibrium-based MARL algorithms cannot scale due to a large number of computationally expensive equilibrium computations (e.g., computing Nash equilibria is PPAD-hard) during learning. For the first time, this paper finds that during the learning process of equilibrium-based MARL, the one-shot games corresponding to each state's successive visits often have the same or similar equilibria (for some states more than 90% of games corresponding to successive visits have similar equilibria). Inspired by this observation, this paper proposes to use equilibrium transfer to accelerate equilibrium-based MARL. The key idea of equilibrium transfer is to reuse previously computed equilibria when each agent has a small incentive to deviate. By introducing transfer loss and transfer condition, a novel framework called equilibrium transfer-based MARL is proposed. We prove that although equilibrium transfer brings transfer loss, equilibrium-based MARL algorithms can still converge to an equilibrium policy under certain assumptions. Experimental results in widely used benchmarks (e.g., grid world game, soccer game, and wall game) show that the proposed framework: 1) not only significantly accelerates equilibrium-based MARL (up to 96.7% reduction in learning time), but also achieves higher average rewards than algorithms without equilibrium transfer and 2) scales significantly better than algorithms without equilibrium transfer when the state/action space grows and the number of agents increases. PMID:25181517

  19. Status Equilibrium for Local Public Good Economies

    OpenAIRE

    Anne van den Nouweland; Myrna H. Wooders

    2005-01-01

    We introduce a concept of status equilibrium for local public good economies. A status equilibrium specifies one status index for each agent in an economy. These indices determine agents' cost shares in any possible jurisdiction to which the agent might belong. We provide an axiomatic charaterization of status equilibrium using consistency properties.

  20. Mathematical Models and Equilibrium in Irreversible Microeconomics

    OpenAIRE

    Anatoly M. Tsirlin; Sergey A. Amelkin

    2010-01-01

    A set of equilibrium states in a system consisting of economic agents, economic reservoirs, and firms is considered. Methods of irreversible microeconomics are used. We show that direct sale/purchase leads to an equilibrium state which depends upon the coefficients of supply/demand functions. To reach the unique equilibrium state it is necessary to add either monetary exchange or an intermediate firm.

  1. Open problems in non-equilibrium physics

    Energy Technology Data Exchange (ETDEWEB)

    Kusnezov, D.

    1997-09-22

    The report contains viewgraphs on the following: approaches to non-equilibrium statistical mechanics; classical and quantum processes in chaotic environments; classical fields in non-equilibrium situations: real time dynamics at finite temperature; and phase transitions in non-equilibrium conditions.

  2. Macroscopic non-equilibrium thermodynamics in dynamic calorimetry

    OpenAIRE

    Garden, Jean-Luc

    2007-01-01

    What is really measured in dynamic calorimetric experiments is still an open question. This paper is devoted to this question, which can be usefully envisaged by means of macroscopic non-equilibrium thermodynamics. From the pioneer work of De Donder on chemical reactions and with other authors along the 20th century, the question is tackled under an historical point of view. A special attention is paid about the notions of frequency dependent complex heat capacity and entropy production due t...

  3. Equilibrium sampling to determine the thermodynamic potential for bioaccumulation of persistent organic pollutants from sediment.

    Science.gov (United States)

    Jahnke, Annika; MacLeod, Matthew; Wickström, Håkan; Mayer, Philipp

    2014-10-01

    Equilibrium partitioning (EqP) theory is currently the most widely used approach for linking sediment pollution by persistent hydrophobic organic chemicals to bioaccumulation. Most applications of the EqP approach assume (I) a generic relationship between organic carbon-normalized chemical concentrations in sediments and lipid-normalized concentrations in biota and (II) that bioaccumulation does not induce levels exceeding those expected from equilibrium partitioning. Here, we demonstrate that assumption I can be obviated by equilibrating a silicone sampler with chemicals in sediment, measuring chemical concentrations in the silicone, and applying lipid/silicone partition ratios to yield concentrations in lipid at thermodynamic equilibrium with the sediment (CLip⇌Sed). Furthermore, we evaluated the validity of assumption II by comparing CLip⇌Sed of selected persistent, bioaccumulative and toxic pollutants (polychlorinated biphenyls (PCBs) and hexachlorobenzene (HCB)) to lipid-normalized concentrations for a range of biota from a Swedish background lake. PCBs in duck mussels, roach, eel, pikeperch, perch and pike were mostly below the equilibrium partitioning level relative to the sediment, i.e., lipid-normalized concentrations were ≤CLip⇌Sed, whereas HCB was near equilibrium between biota and sediment. Equilibrium sampling allows straightforward, sensitive and precise measurement of CLip⇌Sed. We propose CLip⇌Sed as a metric of the thermodynamic potential for bioaccumulation of persistent organic chemicals from sediment useful to prioritize management actions to remediate contaminated sites. PMID:25184484

  4. Risk premia in general equilibrium

    DEFF Research Database (Denmark)

    Posch, Olaf

    solutions of dynamic stochastic general equilibrium models, including a novel solution with endogenous labor supply, to obtain closed-form expressions for the risk premium in production economies. We find that the curvature of the policy functions affects the risk premium through controlling the individual......This paper shows that non-linearities can generate time-varying and asymmetric risk premia over the business cycle. These (empirical) key features become relevant and asset market implications improve substantially when we allow for non-normalities in the form of rare disasters. We employ explicit......'s effective risk aversion....

  5. Conformations of Proteins in Equilibrium

    Energy Technology Data Exchange (ETDEWEB)

    Micheletti, Cristian; Banavar, Jayanth R.; Maritan, Amos

    2001-08-20

    We introduce a simple theoretical approach for an equilibrium study of proteins with known native-state structures. We test our approach with results on well-studied globular proteins, chymotrypsin inhibitor (2ci2), barnase, and the alpha spectrin SH3 domain, and present evidence for a hierarchical onset of order on lowering the temperature with significant organization at the local level even at high temperatures. A further application to the folding process of HIV-1 protease shows that the model can be reliably used to identify key folding sites that are responsible for the development of drug resistance.

  6. Equilibrium emission of nuclear fragments

    International Nuclear Information System (INIS)

    In the present paper data are presented which demonstrate that for IMF production the use of intermediate energy heavy-ion-induced reactions at energies of 15-30 MeV/nucleon is extremely tenuous due to the possibility of contributions from deep inelastic collisions, fission and from preequilibrium mechanisms. Furthermore it is argued that the apparent temperatures extracted from the slopes of the fragment energy spectra correlate with the reaction variables in a manner which is more consistent with pre-equilibrium emission in the spirit of the exciton model, instead of a spatially localized thermal excitation or a 'hot spot'. (orig./BBOE)

  7. Vapour-liquid equilibrium in the monoethylene glycol - methane system at elevated pressures

    OpenAIRE

    Bersås, Anita

    2012-01-01

    A range of different chemicals are used in natural gas processing. The systems operate in closed loops, but a small amount of the chemicals are lost due to the solubility of the chemical in the gas phase. This leads to increased operational costs, it may cause HSE related problems, and it can lead to operational difficulties and contamination of downstream processes and products. A limited number of vapour-liquid equilibrium, VLE, data for processing chemicals in methane are available in...

  8. Boson spectra and correlations for thermal locally equilibrium systems

    CERN Document Server

    Sinyukov, Yu M

    1999-01-01

    The single- and multi- particle inclusive spectra for strongly inhomogeneous thermal boson systems are studied using the method of statistical operator. The thermal Wick's theorem is generalized and the analytical solution of the problem for an boost-invariant expanding boson gas is found. The results demonstrate the effects of inhomogeneity for such a system: the spectra and correlations for particles with wave-lengths larger than the system's homogeneity lengths change essentially as compared with the results based on the local Bose-Einstein thermal distributions. The effects noticeable grow for overpopulated media, where the chemical potential associated with violation of chemical equilibrium is large enough.

  9. Equilibrium composition for the reaction of plutonium hydride with air

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    There are six independent constituents with 4 chemical elements, i.e. PuH2.7(s), PuN(s), Pu2O3(s), N2, O2 and H2, therefore , the system described involves of 2 independent reactions ,both those of the experimental, which indicates that the chemical equilibrium is nearly completely approached. Therefore, it is believed that the reaction rate of plutonium hydride with air is extremely rapid. The present paper has briefly discussed the simultaneous reactions and its thermodynamic coupling effect.

  10. Boson spectra and correlations for thermal locally equilibrium systems

    International Nuclear Information System (INIS)

    The single- and multi-particle inclusive spectra for strongly inhomogeneous thermal boson systems are studied using the method of statistical operator. The thermal Wick's theorem is generalized and the analytical solution of the problem for a boost-invariant expanding boson gas is found. The results demonstrate the effects of inhomogeneity for such a system: the spectra and correlations for particles with wavelengths larger than the system's homogeneity lengths change essentially as compared with the results based on the local Bose-Einstein thermal distributions. The effects noticeably grow for overpopulated media, where the chemical potential associated with violation of chemical equilibrium is large enough. (author)

  11. Departures from Local Thermodynamic Equilibrium

    International Nuclear Information System (INIS)

    This paper starts with a definition of local thermodynamic equilibrium and points out the relationship between local and complete thermodynamic equilibrium. It is shown that electron collisions are essential for the establishment of LTE and a relationship is derived for the minimum electron density at which collision processes are just sufficiently frequent to cause the plasma to be in LTE in face of the competing radiative processes. This relationship is derived for an optically thin plasma. The effect of radiation trapping is considered and some figures given by which the effect of this can be taken into account in assessing the validity of LTE in such cases. Account is now taken of the finite time required for the atomic collision processes to establish the plasma in LTE. A numerical example is worked out which shows that these considerations can be very important for plasmas of rapidly varying temperature. Mention is also made of departures from LTE caused by inhomogeneities in the plasma and by the positive ions having a different kinetic temperature from the electrons. Finally, it is remarked that even if the criteria for LTE to be valid are not met then the Saha and Boltzmann equations may still be applied to describe the population densities of the upper levels of individual species of atoms or ions. (author)

  12. Pre-equilibrium plasma dynamics

    International Nuclear Information System (INIS)

    Approaches towards understanding and describing the pre-equilibrium stage of quark-gluon plasma formation in heavy-ion collisions are reviewed. Focus is on a kinetic theory approach to non-equilibrium dynamics, its extension to include the dynamics of color degrees of freedom when applied to the quark-gluon plasma, its quantum field theoretical foundations, and its relationship to both the particle formation stage at the very beginning of the nuclear collision and the hydrodynamic stage at late collision times. The usefulness of this approach to obtain the transport coefficients in the quark-gluon plasma and to derive the collective mode spectrum and damping rates in this phase are discussed. Comments are made on the general difficulty to find appropriated initial conditions to get the kinetic theory started, and a specific model is given that demonstrates that, once given such initial conditions, the system can be followed all the way through into the hydrodynamical regime. 39 refs., 7 figs

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

    International Nuclear Information System (INIS)

    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)

  14. The standard genetic code and its relation to mutational pressure: robustness and equilibrium criteria

    International Nuclear Information System (INIS)

    Under the assumption of even point mutation pressure on the DNA strand, rates for transitions from one amino acid into another were assessed. Nearly 25% of all mutations were silent. About 48% of the mutations from a given amino acid stream either into the same amino acid or into an amino acid of the same class. These results suggest a great stability of the Standard Genetic Code respect to mutation load. Concepts from chemical equilibrium theory are applicable into this case provided that mutation rate constants are given. It was obtained that unequal synonymic codon usage may lead to changes in the equilibrium concentrations. Data from real biological species showed that several amino acids are close to the respective equilibrium concentration. However in all the cases the concentration of leucine nearly doubled its equilibrium concentration, whereas for the stop command (Term) it was about 10 times lower. The overall distance from equilibrium for a set of species suggests that eukaryotes are closer to equilibrium than prokaryotes, and the HIV virus was closest to equilibrium among 15 species. We obtained that contemporary species are closer to the equilibrium than the Last Universal Common Ancestor (LUCA) was. Similarly, nonpreserved regions in proteins are closer to equilibrium than the preserved ones. We suggest that this approach can be useful for exploring some aspects of biological evolution in the framework of Standard Genetic Code properties. (author)

  15. Equilibrium structure of ferrofluid aggregates

    International Nuclear Information System (INIS)

    We study the equilibrium structure of large but finite aggregates of magnetic dipoles, representing a colloidal suspension of magnetite particles in a ferrofluid. With increasing system size, the structural motif evolves from chains and rings to multi-chain and multi-ring assemblies. Very large systems form single- and multi-wall coils, tubes and scrolls. These structural changes result from a competition between various energy terms, which can be approximated analytically within a continuum model. We also study the effect of external parameters such as magnetic field on the relative stability of these structures. Our results may give insight into experimental data obtained during solidification of ferrofluid aggregates at temperatures where thermal fluctuations become negligible in comparison to inter-particle interactions. These data may also help to experimentally control the aggregation of magnetic particles.

  16. Ringed accretion disks: equilibrium configurations

    CERN Document Server

    Pugliese, D

    2015-01-01

    We investigate a model of ringed accretion disk, made up by several rings rotating around a supermassive Kerr black hole attractor. Each toroid of the ringed disk is governed by the General Relativity hydrodynamic Boyer condition of equilibrium configurations of rotating perfect fluids. Properties of the tori can be then determined by an appropriately defined effective potential reflecting the background Kerr geometry and the centrifugal effects. The ringed disks could be created in various regimes during the evolution of matter configurations around supermassive black holes. Therefore, both corotating and counterrotating rings have to be considered as being a constituent of the ringed disk. We provide constraints on the model parameters for the existence and stability of various ringed configurations and discuss occurrence of accretion onto the Kerr black hole and possible launching of jets from the ringed disk. We demonstrate that various ringed disks can be characterized by a maximum number of rings. We pr...

  17. Hierarchical condensation near phase equilibrium

    Science.gov (United States)

    Olemskoi, A. I.; Yushchenko, O. V.; Borisyuk, V. N.; Zhilenko, T. I.; Kosminska, Yu. O.; Perekrestov, V. I.

    2012-06-01

    A novel mechanism of new phase formation is studied both experimentally and theoretically in the example of quasi-equilibrium stationary condensation in an ion-plasma sputterer. Copper condensates are obtained to demonstrate that a specific network structure is formed as a result of self-assembly in the course of deposition. The fractal pattern related is inherent in the phenomena of diffusion limited aggregation. Condensate nuclei are shown to form statistical ensemble of hierarchically subordinated objects distributed in ultrametric space. The Langevin equation and the Fokker-Planck equation related are found to describe stationary distribution of thermodynamic potential variations at condensation. Time dependence of the formation probability of branching structures is found to clarify the experimental situation.

  18. Equilibrium Analysis in Cake Cutting

    DEFF Research Database (Denmark)

    Branzei, Simina; Miltersen, Peter Bro

    2013-01-01

    Cake cutting is a fundamental model in fair division; it represents the problem of fairly allocating a heterogeneous divisible good among agents with different preferences. The central criteria of fairness are proportionality and envy-freeness, and many of the existing protocols are designed to...... guarantee proportional or envy-free allocations, when the participating agents follow the protocol. However, typically, all agents following the protocol is not guaranteed to result in a Nash equilibrium. In this paper, we initiate the study of equilibria of classical cake cutting protocols. We consider one...... of the simplest and most elegant continuous algorithms -- the Dubins-Spanier procedure, which guarantees a proportional allocation of the cake -- and study its equilibria when the agents use simple threshold strategies. We show that given a cake cutting instance with strictly positive value density...

  19. Equilibrium size distribution of rouleaux

    Energy Technology Data Exchange (ETDEWEB)

    Perelson, A.S. (Los Alamos National Lab., NM); Wiegel, F.W.

    1982-02-01

    Rouleaux are formed by the aggregation of red blood cells in the presence of macromolecules that bridge the membranes of adherent erythrocytes. We compute the size and degree of branching of rouleaux for macroscopic systems in thermal equilibrium in the absence of fluid flow. Using techniques from statistical mechanics, analytical expressions are derived for (a) the average number of rouleaux consisting of n cells and having m branch points; (b) the average number of cells per rouleau; (c) the average number of branch points per rouleau; and (d) the number of rouleaux with n cells, n = 1, 2,..., in a system containing a total of N cells. We also present the results of numerical evaluations to establish the validity of asymptotic expressions that simplify our formal analytic results.

  20. A Constructive Generalization of Nash Equilibrium

    CERN Document Server

    Huang, Xiaofei

    2009-01-01

    In a society of multiple individuals, if everybody is only interested in maximizing his own payoff, will there exist any equilibrium for the society? John Nash proved more than 50 years ago that an equilibrium always exists such that nobody would benefit from unilaterally changing his strategy. Nash Equilibrium is a central concept in game theory, which offers the mathematical foundation for social science and economy. However, the original definition is declarative without including a solution to find them. It has been found later that it is computationally difficult to find a Nash equilibrium. Furthermore, a Nash equilibrium may be unstable, sensitive to the smallest variation of payoff functions. Making the situation worse, a society with selfish individuals can have an enormous number of equilibria, making it extremely hard to find out the global optimal one. This paper offers a constructive generalization of Nash equilibrium to cover the case when the selfishness of individuals are reduced to lower level...

  1. Nash Equilibrium in Generalised Muller Games

    OpenAIRE

    Paul, Soumya; Simon, Sunil

    2009-01-01

    We suggest that extending Muller games with preference ordering for players is a natural way to reason about unbounded duration games. In this context, we look at the standard solution concept of Nash equilibrium for non-zero sum games. We show that Nash equilibria always exists for such generalised Muller games on finite graphs and present a procedure to compute an equilibrium strategy profile. We also give a procedure to compute a subgame perfect equilibrium when it exi...

  2. A General Equilibrium Approach of Retail Payments

    OpenAIRE

    Tamás Ilyés; Lóránt Varga

    2015-01-01

    In our paper, we introduce the Hungarian Payment System Model (HUPS), a computable general equilibrium model with detailed payment services which can be used for policy evaluation and forecast. In the last years, several studies investigated different aspects of payment systems and some papers used equilibrium theory to study a specific segment or question of retail payments. In our paper, we take a step forward as we extend this research using the general equilibrium approach. The HUPS model...

  3. Mathematical models and equilibrium in irreversible microeconomics

    Directory of Open Access Journals (Sweden)

    Anatoly M. Tsirlin

    2010-07-01

    Full Text Available A set of equilibrium states in a system consisting of economic agents, economic reservoirs, and firms is considered. Methods of irreversible microeconomics are used. We show that direct sale/purchase leads to an equilibrium state which depends upon the coefficients of supply/demand functions. To reach the unique equilibrium state it is necessary to add either monetary exchange or an intermediate firm.

  4. Equilibrium in CAPM without a Riskless Asset.

    OpenAIRE

    Nielsen, Lars Tyge

    1990-01-01

    In the mean-variance capital asset pricing model without a riskless asset, the possibility of satiation sometimes leads to nonexistence of general equilibrium. Moreover, because portfolio preferences are not necessarily monotone, equilibrium asset prices, when they exist, may be negative or zero. To demonstrate the possibility of nonexistence, and to develop an intuitive understanding of when and why equilibrium does or does not exist, this paper fully investigates the special case of utility...

  5. Coarse Competitive Equilibrium and Extreme Prices

    OpenAIRE

    Faruk Gul; Wolfgang Pesendorfer; Tomasz Strzalecki

    2014-01-01

    We introduce a notion of coarse competitive equilibrium (CCE), to study agents' inability to tailor their consumption to the state of the economy. Our notion is motivated by limited cognitive ability (in particular attention, memory, and complexity) and it maintains the complete market structure of competitive equilibrium. Compared to standard competitive equilibrium, our concept yields riskier allocations and more extreme prices. We provide a tractable model that is suitable for general equi...

  6. Seasonality and equilibrium business cycle theories

    OpenAIRE

    R. Anton Braun; Evans, Charles L.

    1991-01-01

    Barksy-Miron [1989] find that the postwar U.S. economy exhibits a regular seasonal cycle, as well as the business cycle phenomenon. Are these findings consistent with current equilibrium business cycle theories as surveyed by Prescott [1986]? We consider a dynamic, stochastic equilibrium business cycle model which includes deterministic seasonals and nontime-separable preferences. We show how to compute a perfect foresight seasonal equilibrium path for this economy. An approximation to the st...

  7. 1-D EQUILIBRIUM DISCRETE DIFFUSION MONTE CARLO

    Energy Technology Data Exchange (ETDEWEB)

    T. EVANS; ET AL

    2000-08-01

    We present a new hybrid Monte Carlo method for 1-D equilibrium diffusion problems in which the radiation field coexists with matter in local thermodynamic equilibrium. This method, the Equilibrium Discrete Diffusion Monte Carlo (EqDDMC) method, combines Monte Carlo particles with spatially discrete diffusion solutions. We verify the EqDDMC method with computational results from three slab problems. The EqDDMC method represents an incremental step toward applying this hybrid methodology to non-equilibrium diffusion, where it could be simultaneously coupled to Monte Carlo transport.

  8. Determining Equilibrium Position For Acoustical Levitation

    Science.gov (United States)

    Barmatz, M. B.; Aveni, G.; Putterman, S.; Rudnick, J.

    1989-01-01

    Equilibrium position and orientation of acoustically-levitated weightless object determined by calibration technique on Earth. From calibration data, possible to calculate equilibrium position and orientation in presence of Earth gravitation. Sample not levitated acoustically during calibration. Technique relies on Boltzmann-Ehrenfest adiabatic-invariance principle. One converts resonant-frequency-shift data into data on normalized acoustical potential energy. Minimum of energy occurs at equilibrium point. From gradients of acoustical potential energy, one calculates acoustical restoring force or torque on objects as function of deviation from equilibrium position or orientation.

  9. Well-Posedness of MultiCriteria Network Equilibrium Problem

    OpenAIRE

    Zhang, W.Y.

    2014-01-01

    New notions of ϵ-equilibrium flow and ${\\xi }_{{k}_{0}}$ -ϵ-equilibrium flow of multicriteria network equilibrium problem are introduced; an equivalent relation between vector ϵ-equilibrium pattern flow and ${\\xi }_{{k}_{0}}$ -ϵ-equilibrium flow is established. Then, the well-posedness of multicriteria network equilibrium problem is discussed.

  10. Foundations and Application of Non-equilibrium Thermodynamics

    Science.gov (United States)

    Robinson, Gregory

    2011-11-01

    Non-equilibrium thermodynamics provides a powerful but still unfamiliar way to peer into the properties of systems yet unexplored and holds promise for ready application to important engineered systems. This talk will consider some of the challenges, promises, and progress made toward an intuitive statistical theory of non-equilibrium behavior as well as recent work applying it. We will briefly discuss large deviations and the formalism of Freidlin and Wentzell for perturbed dynamical systems, which recasts certain questions about stochastic processes in the form of Hamiltonian mechanics. The methods and their applicability are illustrated by analyzing transitions between different stable states of a chemical reaction network, supplemented by a fast numerical solution of escape trajectories. We conclude with the prospects for using the ideas and methods in the design of more efficient and reliable grid computing platforms, which are crucial both to modern science and the operation of entire industries.

  11. Reflective Equilibrium: Epistemological or Political?

    Directory of Open Access Journals (Sweden)

    Andrew Lister

    2016-01-01

    Full Text Available One of the reasons for ongoing interest in the work of political philosopher John Rawls is that he developed novel methods for thinking systematically about the nature of justice. This paper examines the moral and epistemological motivations for Rawls’s method of “reflective equilibrium,” and the tension between them in Kai Nielsen’s use of “wide reflective equilibrium” in the service of critical and emancipatory social theory. Une des raisons de l’intérêt soutenu pour l’oeuvre du philosophe politique John Rawls est qu’il a développé de nouvelles méthodes de réflexion systématique au sujet de la nature de la justice. Cet article étudie les motifs moraux et épistémologiques soutenant la méthode d’ «équilibre réflectif» de Rawls, et les tensions entre eux dans l’utilisation par Kai Nielsen d’ «équilibre réflectif étendu» au service de la théorie sociale critique et émancipatrice.

  12. Colin Rowe and ' Dynamic Equilibrium'

    Directory of Open Access Journals (Sweden)

    Pablo López Marín

    2015-05-01

    Full Text Available AbstractIn 1944 Gyorgy Kepes published what undoubtless will be his most influential text, "The language of vision". What Kepes tried to do was a guide of grammar and syntax of vision, which allows to face art as purely sensory experience or just visual, devisted of any literary , semantic or sentimental meaning.Among all the concepts that Kepes developes in his essay perhaps the most decisive one is the so called dynamic equilibrium, which is introduced in this work for fi rst time, verbalizing something that was in the air, orbiting around the entire modern plastic but far only explained in an empirical way.Colin Rowe reverberates the recent readed kepesian ideas on his own writings Transparency: Literal and Phenomenal and Neo-'Classicism' and Modern Architecture I and II, when the author tries to highlight the founding principles of the modern movement refusing the plastic  dimension of the discipline . The article will try to expose and explain this influence.

  13. Ringed Accretion Disks: Equilibrium Configurations

    Science.gov (United States)

    Pugliese, D.; Stuchlík, Z.

    2015-12-01

    We investigate a model of a ringed accretion disk, made up by several rings rotating around a supermassive Kerr black hole attractor. Each toroid of the ringed disk is governed by the general relativity hydrodynamic Boyer condition of equilibrium configurations of rotating perfect fluids. Properties of the tori can then be determined by an appropriately defined effective potential reflecting the background Kerr geometry and the centrifugal effects. The ringed disks could be created in various regimes during the evolution of matter configurations around supermassive black holes. Therefore, both corotating and counterrotating rings have to be considered as being a constituent of the ringed disk. We provide constraints on the model parameters for the existence and stability of various ringed configurations and discuss occurrence of accretion onto the Kerr black hole and possible launching of jets from the ringed disk. We demonstrate that various ringed disks can be characterized by a maximum number of rings. We present also a perturbation analysis based on evolution of the oscillating components of the ringed disk. The dynamics of the unstable phases of the ringed disk evolution seems to be promising in relation to high-energy phenomena demonstrated in active galactic nuclei.

  14. Convective Quasi-Equilibrium Reconsidered

    Directory of Open Access Journals (Sweden)

    David J Raymond

    2011-08-01

    Full Text Available The hypothesis of convective quasi-equilibrium states that moist convection reacts almost instantly to drive the atmospheric temperature profile throughout the troposphere to one of a special subset of possible profiles. In a simple case this might consist of a moist adiabat with the saturated moist entropy of the adiabat equaling the moist entropy of the boundary layer. In more complex cases the target temperature profile might depend on the moisture profile as well as boundary layer conditions. We present evidence from analytical and numerical calculations which challenge the validity of this hypothesis. These calculations involve both a simple, physically based parameterization of the effects of convection on its environment and a complex cloud-resolving model. In both cases we show that imposed temperature perturbations in the lower troposphere are rapidly eliminated, while those in the upper troposphere are not. The rapid temperature relaxation in the lower troposphere is due to the near-instantaneous change in the precipitation rate and latent heat release provoked by the temperature anomaly. Water vapor is so limited in the upper troposphere that this process cannot act there.

  15. Allometry in dinosaurs and mammals

    Science.gov (United States)

    Lee, Scott

    2015-03-01

    The proportions of the leg bones change as the size of an animal becomes larger since the mass of the animal increases at a faster rate than the cross-sectional area of its leg bones. For the case of elastic similarity (in which the longitudinal stress in the legs remains constant in animals of all sizes), the diameter d and length L of the femur should be related as d = A L3/2. For geometric similarity (in which all dimensions are scaled by the same factor), d = A L. For animals with femora longer than 20 cm, we find the power law relationship to be d = A Lb with b = 1.13 +/- 0.06 for extant mammals (the largest mammal being Loxodonta africana with a 1.00-m-long femur) and b = 1.18 +/- 0.02 for dinosaurs (the largest dinosaur being Brachiosaurus brancai with a 2.03-m-long femur). These data show that extinct dinosaurs and extant animals scale in the same basic manner. The large sauropods (with femora twice as long as found in elephants) scale in a manner consistent with extrapolation of the scaling shown by extant mammals. These results argue that extinct dinosaurs moved in a manner very similar to extant mammals.

  16. Development of a multi-species mass transport model for concrete with account to thermodynamic phase equilibriums

    DEFF Research Database (Denmark)

    Hosokawa, Yoshifumi; Yamada, Kazuo; Johannesson, Björn;

    2011-01-01

    ) theory alone, not involving chemical processes, have no real practical interest since the chemical action is very dominant for cement based materials. Coupled mass transport and chemical equilibrium models can be used to calculate the variation in pore solution and solid-phase composition when using...

  17. Vertical field and equilibrium calculation in ETE

    International Nuclear Information System (INIS)

    The free-boundary MHD equilibrium code HEQ is used to study the plasma behaviour in the tokamak ETE, with optimized compensations coils and vertical field coils. The changes on the equilibrium parameters for different plasma current values are also investigated. (author). 5 refs., 4 figs., 2 tabs

  18. Competitive equilibrium hyperinflation under rational expectations

    OpenAIRE

    Sallum, Elvia Mureb; Barbosa, Fernando de Holanda; Cunha, Alexandre Barros da

    2005-01-01

    This paper shows that a competitive equilibrium model, where a representative agent maximizes welfare, expectations are rational and markets are in equilibrium can account for several hyperinflation stylized facts. The theory is built by combining two hypotheses, namely, a fiscal crisis that requires printing money to finance an increasing public deficit and a predicted change in an unsustainable fiscal regime.

  19. The method of reflective equilibrium and intuitions

    OpenAIRE

    Langkau, Julia

    2013-01-01

    Reflective equilibrium has been considered a paradigm method involving intuitions. Some philosophers have recently claimed that it is trivial and can even accommodate the sort of scepticism about the reliability of intuitions advocated by experimental philosophers. I discuss several ways in which reflective equilibrium could be thought of as trivial and argue that it is inconsistent with scepticism about the reliability of intuitions.

  20. Equilibrium and stability of the multipole

    International Nuclear Information System (INIS)

    The equilibrium and linear ballooning mode stability of a plasma in an axisymmetric closed field line device such as the multipole is investigated. Two models of the plasma are used, a kinetic model and an ideal MHD model, and the results are compared. Numerical calculations are made of the equilibrium and of ballooning mode stability criteria in the Wisconsin Levitated Octupole device

  1. Zeroth Law, Entropy, Equilibrium, and All That

    Science.gov (United States)

    Canagaratna, Sebastian G.

    2008-01-01

    The place of the zeroth law in the teaching of thermodynamics is examined in the context of the recent discussion by Gislason and Craig of some problems involving the establishment of thermal equilibrium. The concept of thermal equilibrium is introduced through the zeroth law. The relation between the zeroth law and the second law in the…

  2. Equilibrium figures in geodesy and geophysics.

    Science.gov (United States)

    Moritz, H.

    There is an enormous literature on geodetic equilibrium figures, but the various works have not always been interrelated, also for linguistic reasons (English, French, German, Italian, Russian). The author attempts to systematize the various approaches and to use the standard second-order theory for a study of the deviation of the actual earth and of the equipotential reference ellipsoid from an equilibrium figure.

  3. How Far from Equilibrium Is Active Matter?

    Science.gov (United States)

    Fodor, Étienne; Nardini, Cesare; Cates, Michael E.; Tailleur, Julien; Visco, Paolo; van Wijland, Frédéric

    2016-07-01

    Active matter systems are driven out of thermal equilibrium by a lack of generalized Stokes-Einstein relation between injection and dissipation of energy at the microscopic scale. We consider such a system of interacting particles, propelled by persistent noises, and show that, at small but finite persistence time, their dynamics still satisfy a time-reversal symmetry. To do so, we compute perturbatively their steady-state measure and show that, for short persistent times, the entropy production rate vanishes. This endows such systems with an effective fluctuation-dissipation theorem akin to that of thermal equilibrium systems. Last, we show how interacting particle systems with viscous drags and correlated noises can be seen as in equilibrium with a viscoelastic bath but driven out of equilibrium by nonconservative forces, hence providing energetic insight into the departure of active systems from equilibrium.

  4. Economic networks in and out of equilibrium

    CERN Document Server

    Squartini, Tiziano

    2013-01-01

    Economic and financial networks play a crucial role in various important processes, including economic integration, globalization, and financial crises. Of particular interest is understanding whether the temporal evolution of a real economic network is in a (quasi-)stationary equilibrium, i.e. characterized by smooth structural changes rather than abrupt transitions. Smooth changes in quasi-equilibrium networks can be generally controlled for, and largely predicted, via an appropriate rescaling of structural quantities, while this is generally not possible for abrupt transitions in non-stationary networks. Here we study whether real economic networks are in or out of equilibrium by checking their consistency with quasi-equilibrium maximum-entropy ensembles of graphs. As illustrative examples, we consider the International Trade Network (ITN) and the Dutch Interbank Network (DIN). We show that, despite the globalization process, the ITN is an almost perfect example of quasi-equilibrium network, while the DIN ...

  5. Disturbances in equilibrium function after major earthquake

    Science.gov (United States)

    Honma, Motoyasu; Endo, Nobutaka; Osada, Yoshihisa; Kim, Yoshiharu; Kuriyama, Kenichi

    2012-10-01

    Major earthquakes were followed by a large number of aftershocks and significant outbreaks of dizziness occurred over a large area. However it is unclear why major earthquake causes dizziness. We conducted an intergroup trial on equilibrium dysfunction and psychological states associated with equilibrium dysfunction in individuals exposed to repetitive aftershocks versus those who were rarely exposed. Greater equilibrium dysfunction was observed in the aftershock-exposed group under conditions without visual compensation. Equilibrium dysfunction in the aftershock-exposed group appears to have arisen from disturbance of the inner ear, as well as individual vulnerability to state anxiety enhanced by repetitive exposure to aftershocks. We indicate potential effects of autonomic stress on equilibrium function after major earthquake. Our findings may contribute to risk management of psychological and physical health after major earthquakes with aftershocks, and allow development of a new empirical approach to disaster care after such events.

  6. Ethanol reforming in non-equilibrium plasma of glow discharge

    CERN Document Server

    Levko, D

    2012-01-01

    The results of a detailed kinetic study of the main plasma chemical processes in non-equilibrium ethanol/argon plasma are presented. It is shown that at the beginning of the discharge the molecular hydrogen is mainly generated in the reaction of ethanol H-abstraction. Later hydrogen is formed from active H, CH2OH and CH3CHOH and formaldehyde. Comparison with experimental data has shown that the used kinetic mechanism predicts well the concentrations of main species at the reactor outlet.

  7. Theoretical investigation to thermal equilibrium concentration of point defect through first-principles calculation

    Directory of Open Access Journals (Sweden)

    Akihide Kuwabara

    2007-01-01

    Full Text Available First-principles calculations based on density functional theory enable us to quantify the thermal equilibrium concentration of a point defect through calculating the formation energy of the defect. In order to know the formation energy, we need three parameters: the energy difference between defective and perfect systems, chemical potential of constitutive atoms and Fermi level. The energy difference is obtained from calculations based on "supercell method". The energy of a supercell with a charged defect should be corrected by an appropriate way such as alignment of electrostatic potential. The chemical potential and Fermi level can be fixed from conditions of phase equilibrium and charge neutrality.

  8. Molecular Thermodynamics for Chemical Process Design

    Science.gov (United States)

    Prausnitz, J. M.

    1976-01-01

    Discusses that aspect of thermodynamics which is particularly important in chemical process design: the calculation of the equilibrium properties of fluid mixtures, especially as required in phase-separation operations. (MLH)

  9. Lateral interactions and non-equilibrium in surface kinetics

    Science.gov (United States)

    Menzel, Dietrich

    2016-08-01

    Work modelling reactions between surface species frequently use Langmuir kinetics, assuming that the layer is in internal equilibrium, and that the chemical potential of adsorbates corresponds to that of an ideal gas. Coverage dependences of reacting species and of site blocking are usually treated with simple power law coverage dependences (linear in the simplest case), neglecting that lateral interactions are strong in adsorbate and co-adsorbate layers which may influence kinetics considerably. My research group has in the past investigated many co-adsorbate systems and simple reactions in them. We have collected a number of examples where strong deviations from simple coverage dependences exist, in blocking, promoting, and selecting reactions. Interactions can range from those between next neighbors to larger distances, and can be quite complex. In addition, internal equilibrium in the layer as well as equilibrium distributions over product degrees of freedom can be violated. The latter effect leads to non-equipartition of energy over molecular degrees of freedom (for products) or non-equal response to those of reactants. While such behavior can usually be described by dynamic or kinetic models, the deeper reasons require detailed theoretical analysis. Here, a selection of such cases is reviewed to exemplify these points.

  10. A Multi Period Equilibrium Pricing Model

    CERN Document Server

    Pirvu, Traian A

    2012-01-01

    In this paper, we propose an equilibrium pricing model in a dynamic multi-period stochastic framework with uncertain income streams. In an incomplete market, there exist two traded risky assets (e.g. stock/commodity and weather derivative) and a non-traded underlying (e.g. temperature). The risk preferences are of exponential (CARA) type with a stochastic coefficient of risk aversion. Both time consistent and time inconsistent trading strategies are considered. We obtain the equilibriums prices of a contingent claim written on the risky asset and non-traded underlying. By running numerical experiments we examine how the equilibriums prices vary in response to changes in model parameters.

  11. Rotamak equilibrium calculations using the PEST code

    International Nuclear Information System (INIS)

    This report describes the use of the equilibrium part of the Princeton equilibrium and stability code PEST to model rotamak equilibria with an applied toroidal magnetic field. An overview of the code is provided, together with a list of required input data. The simulation of a range of equilibria measured in the ANSTO rotamak shows that the rotamak approximately satisfies magnetohydrodynamic equilibrium. Of particular interest is the presence of large diamagnetic poloidal current about the magnetic axis which produces a peak in the plasma pressure on the magnetic axis. For a low toroidal field, however, poloidal current of opposite direction is simultaneously driven on flux surfaces distant from the magnetic axis, producing paramagnetism

  12. Equilibrium solubilities of iodine vapor in water

    International Nuclear Information System (INIS)

    Equilibrium solubilities of iodine vapor in water were measured by introducing iodine vapor, in equilibrium with solid iodine, into water and by circulating it in a closed system, and Henry's law constants were determined. Equilibrium distributions of iodine vapor between a gas phase and an aqueous phase were also measured by another method, and partition coefficients were determined. The solubilities of iodine vapor in water estimated from both the Henry's law constants and the partition coefficients are compared with those of solid iodine reported in the literature. Thermodynamic parameters for the hydration of iodine vapor are evaluated experimentally. (author)

  13. Chemical Kinetics on Extrasolar Planets

    CERN Document Server

    Moses, Julianne I

    2013-01-01

    Chemical kinetics plays an important role in controlling the atmospheric composition of all planetary atmospheres, including those of extrasolar planets. For the hottest exoplanets, the composition can closely follow thermochemical-equilibrium predictions, at least in the visible and infrared photosphere at dayside (eclipse) conditions. However, for atmospheric temperatures < ~2000 K, and in the uppermost atmosphere at any temperature, chemical kinetics matters. The two key mechanisms by which kinetic processes drive an exoplanet atmosphere out of equilibrium are photochemistry and transport-induced quenching. We review these disequilibrium processes in detail, discuss observational consequences, and examine some of the current evidence for kinetic processes on extrasolar planets.

  14. Steady state equilibrium condition of npe± gas and its application to astrophysics *

    Institute of Scientific and Technical Information of China (English)

    Men-Quan Liu

    2011-01-01

    The steady equilibrium conditions for a mixed gas of neutrons, protons,electrons, positrons and radiation fields (abbreviated as npe± gas) with or without external neutrino flux are investigated, and a general chemical potential equilibrium equationμn =μp + Cμe is obtained to describe the steady equilibrium at high temperatures (T > 109 K). An analytic fitting formula of coefficient C is presented for the sake of simplicity, when neutrinos and antineutrinos are transparent. It is a simple method to estimate the electron fraction for the steady equilibrium npe± gas that adopts the corresponding equilibrium condition. As an example, we apply this method to the GRB accretion disk and confirm that the composition in the inner region is approximately in equilibrium when the accretion rate is low. For the case with external neutrino flux, we calculate the initial electron fraction of neutrino-driven wind from the proto-neutron star model M 15-11-rl. The results show that the improved equilibrium condition makes the electron fraction decrease significantly more than the case μn = μp +μe when the time is less than 5 s post bounce, which may be useful for r-process nucleosynthesis models.

  15. Quasilocal energy and thermodynamic equilibrium conditions

    CERN Document Server

    Uzun, Nezihe

    2015-01-01

    Equilibrium thermodynamic laws are typically applied to horizons in general relativity without stating the conditions that bring them into equilibrium. We fill this gap by applying a new thermodynamic interpretation to a generalized Raychaudhuri equation for a closed spacelike 2-surface, the "screen", which encompasses a system of arbitrary size in nonequilibrium with its surroundings in general. In the case of spherical symmetry this enables us to identify quasilocal thermodynamic potentials directly related to standard quasilocal energy definitions. Quasilocal thermodynamic equilibrium is defined by minimizing the mean extrinsic curvature of the screen. Moreover, without any direct reference to surface gravity, we find that the system comes into quasilocal thermodynamic equilibrium when the screen is located at a generalized apparent horizon. Examples of the Schwarzschild, Friedmann-Lemaitre and Lemaitre-Tolman geometries are investigated and compared. Conditions for the quasilocal thermodynamic and hydrody...

  16. Plasma equilibrium and instabilities in tokamaks

    International Nuclear Information System (INIS)

    A phenomenological introduction of some of the main theoretical and experimental features on equilibrium and instabilities in tokamaks is presented. In general only macroscopic effects are considered, being the plasma described as a fluid. (L.C.)

  17. Equilibrium Reconstruction on the Large Helical Device

    Energy Technology Data Exchange (ETDEWEB)

    Samuel A. Lazerson, D. Gates, D. Monticello, H. Neilson, N. Pomphrey, A. Reiman S. Sakakibara, and Y. Suzuki

    2012-07-27

    Equilibrium reconstruction is commonly applied to axisymmetric toroidal devices. Recent advances in computational power and equilibrium codes have allowed for reconstructions of three-dimensional fields in stellarators and heliotrons. We present the first reconstructions of finite beta discharges in the Large Helical Device (LHD). The plasma boundary and magnetic axis are constrained by the pressure profile from Thomson scattering. This results in a calculation of plasma beta without a-priori assumptions of the equipartition of energy between species. Saddle loop arrays place additional constraints on the equilibrium. These reconstruction utilize STELLOPT, which calls VMEC. The VMEC equilibrium code assumes good nested flux surfaces. Reconstructed magnetic fields are fed into the PIES code which relaxes this constraint allowing for the examination of the effect of islands and stochastic regions on the magnetic measurements.

  18. Effect of Ultrasound on Desorption Equilibrium

    Institute of Scientific and Technical Information of China (English)

    秦炜; 原永辉; 戴猷元

    2001-01-01

    Effects of ultrasound on intensification of separation process were investigated through the experiment of desorption equilibrium behavior. Tri-butyl phosphate (TBP) on NKA-X resin and phenol on a solvent impregnated resin, CL-TBP resin, were used for desorption processes. The desorption rate was measured with and without ultrasound. Desorption equilibrium was studied under various ultrasonic power densities or thermal infusion. Results showed that the desorption rate with ultrasound was much higher than that with normal thermal infusion. Both ultrasound and thermal infusion broke the desorption equilibrium existed at room temperature. However, after the systems were cooled down, the amount of solute desorbed in the liquid phase in the presence of ultrasound was much higher than that at the temperature corresponding to the same ultrasound power. It is proved that the initial desorption equilibrium was broken as a result of the spot energy effect of ultrasound.

  19. Chemical transport reactions

    CERN Document Server

    Schäfer, Harald

    2013-01-01

    Chemical Transport Reactions focuses on the processes and reactions involved in the transport of solid or liquid substances to form vapor phase reaction products. The publication first offers information on experimental and theoretical principles and the transport of solid substances and its special applications. Discussions focus on calculation of the transport effect of heterogeneous equilibria for a gas motion between equilibrium spaces; transport effect and the thermodynamic quantities of the transport reaction; separation and purification of substances by means of material transport; and

  20. Numerical verification of equilibrium chemistry software within nuclear fuel performance codes

    International Nuclear Information System (INIS)

    A numerical tool is in an advanced state of development to compute the equilibrium compositions of phases and their proportions in multi-component systems of importance to the nuclear industry. The resulting software is being conceived for direct integration into large multi-physics fuel performance codes, particularly for providing transport source terms, material properties, and boundary conditions in heat and mass transport modules. Consequently, any numerical errors produced in equilibrium chemistry computations will be propagated in subsequent heat and mass transport calculations, thus falsely predicting nuclear fuel behaviour. The necessity for a reliable method to numerically verify chemical equilibrium computations is emphasized by the requirement to handle the very large number of elements necessary to capture the entire fission product inventory. A simple, reliable and comprehensive numerical verification method called the Gibbs Criteria is presented which can be invoked by any equilibrium chemistry solver for quality assurance purposes. (author)

  1. Non-equilibrium Lyapunov function and a fluctuation relation for stochastic systems: Poisson representation approach

    CERN Document Server

    Petrosyan, K G

    2014-01-01

    We present a statistical physics framework for description of nonlinear non-equilibrium stochastic processes, modeled via chemical master equation, in the weak-noise limit. Using the Poisson representation approach and applying the large-deviation principle we first solve the master equation. Then we use the notion of the non-equilibrium free energy to derive an integral fluctuation relation for nonlinear non-equilibrium systems under feedback control. We point out that the free energy as well as some functionals can serve as non-equilibrium Lyapunov function which has an important property to decay to its minimal value monotonously at all times. The Poisson representation technique is illustrated via exact stochastic treatment of biophysical processes, such as bacterial chemosensing and molecular evolution.

  2. On financial equilibrium with intermediation costs

    DEFF Research Database (Denmark)

    Markeprand, Tobias Ejnar

    2008-01-01

    This paper studies the set of competitive equilibria in financial economies with intermediation costs. We consider an arbitrary dividend structure, which includes options and equity with limited liabilities.We show a general existence result and upper-hemi continuity of the equilibrium...... correspondence. Finally, we prove that when intermediation costs approach zero, unbounded volume of asset trades is a necessary and sufficient condition, provided that, there is no financial equilibrium without intermediation costs....

  3. Default and Credit Constraint in General equilibrium

    OpenAIRE

    Xavier Ragot; François Le Grand

    2011-01-01

    We study an economy where infinitely living agents face uninsurable shocks and are allowed default on their debt. After having defaulted, agents are excluded from the economy. We present a equilibrium definition allowing for both credit constraints and default inequilibrium. Indeed, existing theories introduce either default of credit constraint in general equilibrium, but never both. We prove that the optimal allocation includes both credit constraints and default, while the market allocatio...

  4. Existence and stability of Nash equilibrium

    CERN Document Server

    Carmona, Guilherme

    2012-01-01

    The book aims at describing the recent developments in the existence and stability of Nash equilibrium. The two topics are central to game theory and economics and have been extensively researched. Recent results on existence and stability of Nash equilibrium are scattered and the relationship between them has not been explained clearly. The book will make these results easily accessible and understandable to researchers in the field.

  5. Equilibrium labour turnover, firm growth and unemployment

    OpenAIRE

    Coles, Melvyn G; Dale T. Mortensen

    2012-01-01

    This paper identifies a data-consistent, equilibrium model of unemployment, wage dispersion, quit turnover and firm growth dynamics. In a separating equilibrium, more productive firms signal their type by paying strictly higher wages in every state of the market. Workers optimally quit to firms paying a higher wage and so move effciently from less to more productive firms. Start-up firms are initially small and grow endogenously over time. Consistent with Gibrat's law, individual firm growth ...

  6. The Cournot Equilibrium for n Firms

    Directory of Open Access Journals (Sweden)

    Gina Ioan

    2015-05-01

    Full Text Available Oligopoly is a market situation where there are a small number of bidders (at least two of a good non-substituent and a sufficient number of consumers. The paper analyses the Cournot equilibrium in both cases where each firm assumes the role of leadership and after when firms act simultaneously on market. There are obtained the equilibrium productions, maximum profits and sales price.

  7. An Equilibrium Analysis of Real Estate Leases

    OpenAIRE

    Steven R. Grenadier

    2005-01-01

    This article provides a unified equilibrium approach to valuing commercial real estate leases. Using a game-theoretic variant of real options analysis, the underlying real estate asset market is modeled as a continuous-time Nash equilibrium, where developers make construction decisions under demand uncertainty. Then, using the economic notion that leasing represents the purchase of the use of the asset over a specified time, I use a contingent-claims approach to value many of the most common ...

  8. Equilibrium fluctuation energy of gyrokinetic plasma

    International Nuclear Information System (INIS)

    The thermal equilibrium electric field fluctuation energy of the gyrokinetic model of magnetized plasma is computed, and found to be smaller than the well-known result (k)/8π = 1/2T/[1 + (klambda/sub D/)2] valid for arbitrarily magnetized plasmas. It is shown that, in a certain sense, the equilibrium electric field energy is minimum in the gyrokinetic regime. 13 refs., 2 figs

  9. original: Operational spatial computable general equilibrium modeling

    OpenAIRE

    Johannes BrÃcker

    1998-01-01

    A prototype spatial computable general equilibrium model is developed and illustrated by a numerical example. The theoretical basis is a complete Arrow-Debreu equilibrium under perfect competition. The leading principle of model design is parsimony: The specification restricts the number of parameters in a way allowing for a model calibration relying on a limited data base, which is readily available in a country with a well developed statistical service. No "data generating" first stage, usi...

  10. The Theory of Variances in Equilibrium Reconstruction

    Energy Technology Data Exchange (ETDEWEB)

    Zakharov, Leonid E.; Lewandowski, Jerome; Foley, Elizabeth L.; Levinton, Fred M.; Yuh, Howard Y.; Drozdov, Vladimir; McDonald, Darren

    2008-01-14

    The theory of variances of equilibrium reconstruction is presented. It complements existing practices with information regarding what kind of plasma profiles can be reconstructed, how accurately, and what remains beyond the abilities of diagnostic systems. The σ-curves, introduced by the present theory, give a quantitative assessment of quality of effectiveness of diagnostic systems in constraining equilibrium reconstructions. The theory also suggests a method for aligning the accuracy of measurements of different physical nature.

  11. The Theory of Variances in Equilibrium Reconstruction

    International Nuclear Information System (INIS)

    The theory of variances of equilibrium reconstruction is presented. It complements existing practices with information regarding what kind of plasma profiles can be reconstructed, how accurately, and what remains beyond the abilities of diagnostic systems. The σ-curves, introduced by the present theory, give a quantitative assessment of quality of effectiveness of diagnostic systems in constraining equilibrium reconstructions. The theory also suggests a method for aligning the accuracy of measurements of different physical nature

  12. Theory for non-equilibrium statistical mechanics.

    Science.gov (United States)

    Attard, Phil

    2006-08-21

    This paper reviews a new theory for non-equilibrium statistical mechanics. This gives the non-equilibrium analogue of the Boltzmann probability distribution, and the generalization of entropy to dynamic states. It is shown that this so-called second entropy is maximized in the steady state, in contrast to the rate of production of the conventional entropy, which is not an extremum. The relationships of the new theory to Onsager's regression hypothesis, Prigogine's minimal entropy production theorem, the Langevin equation, the formula of Green and Kubo, the Kawasaki distribution, and the non-equilibrium fluctuation and work theorems, are discussed. The theory is worked through in full detail for the case of steady heat flow down an imposed temperature gradient. A Monte Carlo algorithm based upon the steady state probability density is summarized, and results for the thermal conductivity of a Lennard-Jones fluid are shown to be in agreement with known values. Also discussed is the generalization to non-equilibrium mechanical work, and to non-equilibrium quantum statistical mechanics. As examples of the new theory two general applications are briefly explored: a non-equilibrium version of the second law of thermodynamics, and the origin and evolution of life. PMID:16883388

  13. Analysis of non-equilibrium phenomena in inductively coupled plasma generators

    Science.gov (United States)

    Zhang, W.; Lani, A.; Panesi, M.

    2016-07-01

    This work addresses the modeling of non-equilibrium phenomena in inductively coupled plasma discharges. In the proposed computational model, the electromagnetic induction equation is solved together with the set of Navier-Stokes equations in order to compute the electromagnetic and flow fields, accounting for their mutual interaction. Semi-classical statistical thermodynamics is used to determine the plasma thermodynamic properties, while transport properties are obtained from kinetic principles, with the method of Chapman and Enskog. Particle ambipolar diffusive fluxes are found by solving the Stefan-Maxwell equations with a simple iterative method. Two physico-mathematical formulations are used to model the chemical reaction processes: (1) A Local Thermodynamics Equilibrium (LTE) formulation and (2) a thermo-chemical non-equilibrium (TCNEQ) formulation. In the TCNEQ model, thermal non-equilibrium between the translational energy mode of the gas and the vibrational energy mode of individual molecules is accounted for. The electronic states of the chemical species are assumed in equilibrium with the vibrational temperature, whereas the rotational energy mode is assumed to be equilibrated with translation. Three different physical models are used to account for the coupling of chemistry and energy transfer processes. Numerical simulations obtained with the LTE and TCNEQ formulations are used to characterize the extent of non-equilibrium of the flow inside the Plasmatron facility at the von Karman Institute. Each model was tested using different kinetic mechanisms to assess the sensitivity of the results to variations in the reaction parameters. A comparison of temperatures and composition profiles at the outlet of the torch demonstrates that the flow is in non-equilibrium for operating conditions characterized by pressures below 30 000 Pa, frequency 0.37 MHz, input power 80 kW, and mass flow 8 g/s.

  14. Connecting Solubility, Equilibrium, and Periodicity in a Green, Inquiry Experiment for the General Chemistry Laboratory

    Science.gov (United States)

    Cacciatore, Kristen L.; Amado, Jose; Evans, Jason J.; Sevian, Hannah

    2008-01-01

    We present a novel first-year chemistry laboratory experiment that connects solubility, equilibrium, and chemical periodicity concepts. It employs a unique format that asks students to replicate experiments described in different sample lab reports, each lacking some essential information, rather than follow a scripted procedure. This structure is…

  15. Solvents for CO2 capture. Structure-activity relationships combined with vapour-liquid-equilibrium measurements

    NARCIS (Netherlands)

    Mergler, Y.L.; Rumley-Van Gurp, R.; Brasser, P.; Koning, M.C. de; Goetheer, E.L.V.

    2011-01-01

    In this study a systematic approach was chosen to test and characterize amine systems for CO2 capture. Vapour-liquid-equilibrium measurements were performed on a homologue series of amines, with ethylene amine as base structure. Various functional groups were used that ranged in chemical and physica

  16. Simulation of Solid-Liquid Equilibrium in a Ternary System with Adduct Compounds

    Czech Academy of Sciences Publication Activity Database

    Malijevská, I.; Sedláková, Zuzana

    Kuala Lumpur : -, 2007, s. 150-151. [Asian Chemical Congress (12ACC) 2007 /12./. Kuala Lumpur (MY), 23.08.2007-25.08.2007] Institutional research plan: CEZ:AV0Z40720504 Keywords : solid-liquid equilibrium * adduct * ternary system Subject RIV: CF - Physical ; Theoretical Chemistry

  17. Properties of an equilibrium hadron gas subjected to the adiabatic longitudinal expansion

    International Nuclear Information System (INIS)

    We consider an ideal gas of massive hadrons in thermal and chemical equilibrium. The gas expands longitudinally in an adiabatic way. This evolution for a baryonless gas reduces to a hydrodynamic expansion. Cooling process is parametrized by the sound velocity. The sound velocity is temperature dependent and is strongly influenced by hadron mass spectrum. (orig.)

  18. Study of equilibrium using collision dynamics

    International Nuclear Information System (INIS)

    Full text: The heavy-ion collisions at low, intermediate and relativistic energies provide a unique possibility to investigate the different questions ranging from the fusion at low incident energies to the formation of quark-gluon-plasma at higher incident energies. The intermediate energy heavy-ion collisions are excellent tool to study the nuclear equation of state which depends on the temperature as well on the density of the matter. Another important question associated with heavy-ion collision is the degree of equilibrium reached in a reaction. The answer of this question is important as there are several models employed at intermediate energy that assume global (or local) equilibrium. We shall study this question with two different aims. First, we would like to see whether a equilibrium is reached in a heavy-ion collision or not. Secondly, one is interested to know the number of collisions one needs to thermalized the matter. This study is attempted within Quantum Molecular Dynamics (QMD) model [1]. The QMD model is based on molecular dynamics picture where nucleons propagate under the influence of two and three body interactions. Here nucleon-nucleon potential is represented by the Skyrme, Coulomb and Yukawa forces. The question of equilibrium is addressed with the help of rapidity distribution which is defined as: Yi = 1/2 Ln E(i) + pz (i) c / E(i) - pz (i) c Here E(i) and pz(i) denote, respectively, the total energy and longitudinal momentum of the with particle. For a complete equilibrium, one should get a single peak in the distribution at mid rapidity. We calculated the rapidity distribution of Sn-Xe reaction at incident of 50, 400 and 2000 MeV/nucleon. We find that central collisions lead to better global equilibrium whereas peripheral collisions lack equilibrium. Further, one needs 10 collisions for complete equilibrium i.e. for a single peak at mid rapidity distribution. Whereas, if the number of collisions is less than 10, one obtains two peaks

  19. Torque equilibrium attitude control for Skylab reentry

    Science.gov (United States)

    Glaese, J. R.; Kennel, H. F.

    1980-01-01

    The method of torque equilibrium attitude control used to control the reentry of Skylab to an altitude below 150 km without the use of thruster fuel once the attitude was established is discussed. The Skylab attitude and pointing control system, which included rate gyros, sun sensors, star tracker, the Apollo telescope mount digital computer, control moment gyros and cold-gas attitude thrusters, is presented. The 12 torque equilibrium attitudes found at which aerodynamic, gravity gradient and gyroscopic torques would balance are indicated, and the three of those at which the solar power supply would be adequate for attitude control are illustrated. The equilibrium seeking method employed is then examined, and the operation and performance of the torque equilibrium attitude control system during the three weeks prior to Skylab reentry are discussed. It is concluded that the torque equilibrium attitude control method developed for Skylab was successful in performing its assigned mission, and will be valuable for the design of future, low-altitude spacecraft or tethered vehicles.

  20. Planetary cratering 2: Studies of saturation equilibrium

    Science.gov (United States)

    Hartmann, William K.; Gaskell, Robert W.

    1997-01-01

    A realistic computer model has been developed to display images of imaginary cratered surfaces, taking into account empirically measured input size distributions of primary and secondary craters, ejecta blanket morphology including feathering with distance, obliteration due to ejecta from outside the imaged area, lighting effects, etc. The model allows us to track surface evolution of morphology as new craters are added. Using the model as well as lunar photos, we have studied the approach to saturation equilibrium (defined as a condition when no further proportionate increase in crater density occurs as input cratering increases). We find that an identifiable saturation equilibrium occurs close to a level previously identified for this state (Hartmann 1984), typically fluctuating around a crater density from about 0.4 to 2 times that level. This result is fairly robust vis-a-vis the range of model parameters we have chosen. Flooding, basin ejecta blankets, and other obliterative effects can introduce structure and oscillations within this range, even after saturation equilibrium is achieved. These findings may constrain or revise certain earlier interpretations of satellite and planet surface evolution and impactor populations which were predicated on the assumed absence of saturation equilibrium. In our fourth experimental run, we found that suppression of "sandblasting" by sub-resolution impacts allows the smallest secondaries to rise above the saturation equilibrium line, a result that might be relevant to a similar situation on Gaspra and perhaps some other asteroids.

  1. Computational studies in tokamak equilibrium and transport

    International Nuclear Information System (INIS)

    This thesis is concerned with some problems arising in the magnetic confinement approach to controlled thermonuclear fusion. The work address the numerical modelling of equilibrium and transport properties of a confined plasma and the interpretation of experimental data. The thesis is divided in two parts. Part 1 is devoted to some aspects of the MHD equilibrium problem, both in the 'direct' formulation (given an equation for the plasma current, the corresponding equilibrium is to be determined) and in the 'inverse' formulation (the interpretation of measurements at the plasma edge). Part 2 is devoted to numerical studies of the edge plasma. The appropriate Navier-Stokes system of fluid equations is solved in a two-dimensional geometry. The main interest of this work is to develop an understanding of particle and energy transport in the scrape-off layer and onto material boundaries, and also to contribute to the conceptual design of the NET/INTOR tokamak reactor experiment. (Auth.)

  2. Module description of TOKAMAK equilibrium code MEUDAS

    International Nuclear Information System (INIS)

    The analysis of an axisymmetric MHD equilibrium serves as a foundation of TOKAMAK researches, such as a design of devices and theoretical research, the analysis of experiment result. For this reason, also in JAERI, an efficient MHD analysis code has been developed from start of TOKAMAK research. The free boundary equilibrium code ''MEUDAS'' which uses both the DCR method (Double-Cyclic-Reduction Method) and a Green's function can specify the pressure and the current distribution arbitrarily, and has been applied to the analysis of a broad physical subject as a code having rapidity and high precision. Also the MHD convergence calculation technique in ''MEUDAS'' has been built into various newly developed codes. This report explains in detail each module in ''MEUDAS'' for performing convergence calculation in solving the MHD equilibrium. (author)

  3. Module description of TOKAMAK equilibrium code MEUDAS

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, Masaei; Hayashi, Nobuhiko; Matsumoto, Taro; Ozeki, Takahisa [Japan Atomic Energy Research Inst., Naka, Ibaraki (Japan). Naka Fusion Research Establishment

    2002-01-01

    The analysis of an axisymmetric MHD equilibrium serves as a foundation of TOKAMAK researches, such as a design of devices and theoretical research, the analysis of experiment result. For this reason, also in JAERI, an efficient MHD analysis code has been developed from start of TOKAMAK research. The free boundary equilibrium code ''MEUDAS'' which uses both the DCR method (Double-Cyclic-Reduction Method) and a Green's function can specify the pressure and the current distribution arbitrarily, and has been applied to the analysis of a broad physical subject as a code having rapidity and high precision. Also the MHD convergence calculation technique in ''MEUDAS'' has been built into various newly developed codes. This report explains in detail each module in ''MEUDAS'' for performing convergence calculation in solving the MHD equilibrium. (author)

  4. Perturbative Non-Equilibrium Thermal Field Theory

    CERN Document Server

    Millington, Peter

    2013-01-01

    We present a new perturbative formulation of non-equilibrium thermal field theory, based upon non-homogeneous free propagators and time-dependent vertices. Our approach to non-equilibrium dynamics yields time-dependent diagrammatic perturbation series that are free of pinch singularities, without the need to resort to quasi-particle approximation or effective resummations of finite widths. In our formalism, the avoidance of pinch singularities is a consequence of the consistent inclusion of finite-time effects and the proper consideration of the time of observation. After introducing a physically meaningful definition of particle number densities, we derive master time evolution equations for statistical distribution functions, which are valid to all orders in perturbation theory. The resulting equations do not rely upon a gradient expansion of Wigner transforms or involve any separation of time scales. To illustrate the key features of our formalism, we study out-of-equilibrium decay dynamics of unstable par...

  5. Equilibrium Instability of Chiral Mesons in External Electromagnetic Field via AdS/CFT

    CERN Document Server

    Taghavi, Seyed Farid

    2016-01-01

    We study the equilibrium instability of chiral quarkonia in a plasma in the presence of constant magnetic and electric field and at finite axial chemical potential using AdS/CFT duality. The model in use is a supersymmetric QCD at large 't$\\,$Hooft coupling and number of colors. We show that the presence of the magnetic field and the axial chemical potential even in the absence of the electric field make the system unstable. In a gapped system, a stable/unstable equilibrium state phase transition is observed and the initial transition amplitude of the equilibrium state to the non-equilibrium state is investigated. We demonstrate that at zero temperature and large magnetic field the instability grows linearly by increasing the quarkonium binding energy. In the constant electric and magnetic field, the system is in a equilibrium state if the Ohm's law and the chiral magnetic effect cancel their effects. This happens in a sub-space of $(E,B,T,\\mu_5)$ space with constraint equation $\\sigma_B B =- \\sigma E$, where...

  6. Equilibrium instability of chiral mesons in external electromagnetic field via AdS/CFT

    Science.gov (United States)

    Taghavi, Seyed Farid; Vahedi, Ali

    2016-06-01

    We study the equilibrium instability of chiral quarkonia in a plasma in the presence of constant magnetic and electric field and at finite axial chemical potential using AdS/CFT duality. The model in use is a supersymmetric QCD at large 't Hooft coupling and number of colors. We show that the presence of the magnetic field and the axial chemical potential even in the absence of the electric field make the system unstable. In a gapped system, a stable/unstable equilibrium state phase transition is observed and the initial transition amplitude of the equilibrium state to the non-equilibrium state is investigated. We demonstrate that at zero temperature and large magnetic field the instability grows linearly by increasing the quarkonium binding energy. In the constant electric and magnetic field, the system is in a equilibrium state if the Ohm's law and the chiral magnetic effect cancel their effects. This happens in a sub-space of ( E, B, T, μ 5) space with constraint equation σ B B = - σE, where σ and σ B are electric and chiral magnetic conductivity, respectively. We analyze the decay rate of a gapless system when this constraint is slightly violated.

  7. Putting A Human Face on Equilibrium

    Science.gov (United States)

    Glickstein, Neil

    2005-03-01

    A short biography of chemist Fritz Haber is used to personalize the abstract concepts of equilibrium chemistry for high school students in an introductory course. In addition to giving the Haber Bosch process an historic, an economic, and a scientific background the reading and subsequent discussion allows students for whom the human perspective is of paramount importance a chance to investigate the irony of balance or equilibrium in Haber's life story. Since the inclusion of the Haber biography, performance in the laboratory and on examinations for those students who are usually only partially engaged has dramatically improved.

  8. Equilibrium under uncertainty with Sugeno payoff

    OpenAIRE

    Radul, Taras

    2015-01-01

    This paper studies n-player games where players beliefs about their opponents behaviour are capacities. The concept of an equilibrium under uncertainty was introduced J.Dow and S.Werlang (J Econ. Theory 64 (1994) 205--224) for two players and was extended to n-player games by J.Eichberger and D.Kelsey (Games Econ. Behav. 30 (2000) 183--215). Expected utility was expressed by Choquet integral. We consider the concept of an equilibrium under uncertainty in this paper but with expected utility e...

  9. Equilibrium stellar systems with genetic algorithms

    Science.gov (United States)

    Gularte, E.; Carpintero, D. D.

    In 1979, M Schwarzschild showed that it is possible to build an equilibrium triaxial stellar system. However, the linear programmation used to that goal was not able to determine the uniqueness of the solution, nor even if that solution was the optimum one. Genetic algorithms are ideal tools to find a solution to this problem. In this work, we use a genetic algorithm to reproduce an equilibrium spherical stellar system from a suitable set of predefined orbits, obtaining the best solution attainable with the provided set. FULL TEXT IN SPANISH

  10. In Search of Equilibrium: Containers of Light.

    OpenAIRE

    Kamat, Smruti

    2004-01-01

    The goal of this thesis is to find that point of equilibrium in a composition where nothing can be added and nothing can be taken away. Each and every element is vital and any addition or subtraction will disturb this equilibrium. The nature of this investigation requires a program where simplicity is a virtue. The word temple is derived from 'temnere', which means to cut, to take away. I understand this as a process of subtracting to create meaning out of something that would otherwise h...

  11. Micro Data and General Equilibrium Models

    DEFF Research Database (Denmark)

    Browning, Martin; Hansen, Lars Peter; Heckman, James J.

    1999-01-01

    Dynamic general equilibrium models are required to evaluate policies applied at the national level. To use these models to make quantitative forecasts requires knowledge of an extensive array of parameter values for the economy at large. This essay describes the parameters required for different...... economic models, assesses the discordance between the macromodels used in policy evaluation and the microeconomic models used to generate the empirical evidence. For concreteness, we focus on two general equilibrium models: the stochastic growth model extended to include some forms of heterogeneity...

  12. Equilibrium calculations for helical axis stellarators

    International Nuclear Information System (INIS)

    An average method based on a vacuum flux coordinate system is presented. This average method permits the study of helical axis stellarators with toroidally dominated shifts. An ordering is introduced, and to lowest order the toroidally averaged equilibrium equations are reduced to a Grad-Shafranov equation. Also, to lowest order, a Poisson-type equation is obtained for the toroidally varying corrections to the equilibium. By including these corrections, systems that are toroidally dominated, but with significant helical distortion to the equilibrium, may be studied. Numerical solutions of the average method equations are shown to agree well with three-dimensional calculations

  13. General Equilibrium Pricing with Information Asymmetry

    Directory of Open Access Journals (Sweden)

    Yuzhong eZhang

    2015-08-01

    Full Text Available We propose a general equilibrium model for asset pricing that incorporates asymmetric information as the key element determining security prices. In our setting, the concepts of completeness, arbitrage, state price and equivalent martingale measure are extended to the case of asymmetric information. Our model shows that in a so-called quasi-complete market, the agents with differential information can reach an agreement on an universal equilibrium price. The corresponding state price and martingale measure are determined. The key intuition is that agents evaluate consumption choices conditioned on their private information and the public information generated by price. As a consequence, information asymmetry can lead to mispricing as well.

  14. Characterizing the non-equilibrium ionization state of the intergalactic medium

    Science.gov (United States)

    Silvia, Devin W.; O'Shea, Brian W.; Smith, Britton D.; Shull, J. Michael; Turk, Matthew; Reynolds, Daniel

    2015-01-01

    One of the most common ions used to track metals in the intergalactic medium (IGM) is OVI. Ion species in the IGM are typically assumed to be in ionization equilibrium, but owing to the low density of the plasma they may be significantly out of equilibrium. Divergences from equilibrium would make estimates of the amount and evolution of metals in the IGM incorrect. Using a new software package for building and solving complex chemical networks coupled to cosmological hydrodynamic + N-body simulations, we investigate the non-equilibrium properties of the IGM. In particular, we explore how significantly the ionization structure of the IGM diverges from the equilibrium state as a function of time and physical environment. Motivated by the abundant observational data that probes the intergalactic medium via OVI absorption lines in quasar spectra, we track all ionization states of atomic oxygen alongside those of hydrogen and helium. We use the results of these non-equilibrium simulations to characterize the mass content and ionization properties of the IGM and help interpret current observations made by the Cosmic Origins Spectrograph.

  15. Equilibrium shapes of a ferrofluid drop

    OpenAIRE

    Lavrova, O.; Polevikov, V.; Tobiska, L.

    2005-01-01

    A numerical solution strategy for calculating equilibrium free surfaces of a ferrofluid drop under the action of uniform magnetic fields is proposed. Based on this strategy, drop shapes of nonlinear magnetizable fluids are obtained numerically in a wide range of field intensities and compared with existing theoretical results

  16. Non-equilibrium thermodynamics and physical kinetics

    CERN Document Server

    Bikkin, Halid

    2014-01-01

    This graduate textbook covers contemporary directions of non-equilibrium statistical mechanics as well as classical methods of kinetics. With one of the main propositions being to avoid terms such as "obviously" and "it is easy to show", this treatise is an easy-to-read introduction into this traditional, yet vibrant field.

  17. The Foundations of Computable General Equilibrium Theory

    OpenAIRE

    Velupillai, K. Vela

    2005-01-01

    A constructive and recursion theoretic analysis of the standard Computable General Equilibrium (CGE) model of economic theory is undertaken. It is shown, contrary to widely expressed views and textbook versions of the CGE model, that the standard CGE model is neither computable nor constructive in the strict mathematical senses.

  18. Perfect Bayesian equilibrium. Part II: epistemic foundations

    OpenAIRE

    Bonanno, Giacomo

    2011-01-01

    In a companion paper we introduced a general notion of perfect Bayesian equilibrium which can be applied to arbitrary extensive-form games. The essential ingredient of the proposed definition is the qualitative notion of AGM-consistency. In this paper we provide an epistemic foundation for AGM-consistency based on the AGM theory of belief revision.

  19. Identification of Dynamic Stochastic General Equilibrium Models

    OpenAIRE

    Morris, Stephen David

    2014-01-01

    The dissertation "Identification of Dynamic Stochastic General Equilibrium Models" by Stephen David Morris is divided into three chapters. The first chapter considers the statistical implications of common identifying restrictions for DSGE models. The second chapter considers the implications of identification failure for Bayesian estimators. The third chapter considers how identification of nonlinear solutions compares with that of linear solutions

  20. Punctuated equilibrium in an evolving bacterial population

    OpenAIRE

    Chaudhuri, Indranath; Bose, Indrani

    1999-01-01

    Recently, Lenski et al have carried out an experiment on bacterial evolution. Their findings support the theory of punctuated equilibrium in biological evolution. We show that the M=2 Bak-Sneppen model can explain some of the experimental results in a qualitative manner.

  1. Neutrino transport: no asymmetry in equilibrium

    OpenAIRE

    Kusenko, Alexander; Segre, Gino; Vilenkin, Alexander

    1998-01-01

    A small asymmetry in the flux of neutrinos emitted by a hot newly-born neutron star could explain the observed motions of pulsars. However, even in the presence of parity-violating processes with anisotropic scattering amplitudes, no asymmetry is generated in thermal equilibrium. We explain why this no-go theorem stymies some of the proposed explanations for the pulsar ``kick'' velocities.

  2. General Equilibrium Models: Improving the Microeconomics Classroom

    Science.gov (United States)

    Nicholson, Walter; Westhoff, Frank

    2009-01-01

    General equilibrium models now play important roles in many fields of economics including tax policy, environmental regulation, international trade, and economic development. The intermediate microeconomics classroom has not kept pace with these trends, however. Microeconomics textbooks primarily focus on the insights that can be drawn from the…

  3. Testable Restrictions on the Equilibrium Manifold

    OpenAIRE

    Brown, Donald J.; Rosa L. Matzkin

    1995-01-01

    We present a finite system of polynomial inequalities in unobservable variables and market data that observations on market prices, individual incomes and aggregate endowments must satisfy to be consistent with the equilibrium behavior of some pure trade economy. Quantifier elimination is used to derive testable propositions on finite data sets for the pure trade model.

  4. Estimating Equilibrium Effects of Job Search Assistance

    DEFF Research Database (Denmark)

    Gautier, Pieter; Muller, Paul; van der Klaauw, Bas; Rosholm, Michael; Svarer, Michael

    nonparticipants in the experiment regions find jobs slower after the introduction of the activation program (relative to workers in other regions). We then estimate an equilibrium search model. This model shows that a large scale role out of the activation program decreases welfare, while a standard partial...... microeconometric cost-benefit analysis would conclude the opposite....

  5. Specialization and Human Capital in Search Equilibrium

    OpenAIRE

    Mukoyama, Toshihiko; Şahin, Ayşegül

    2005-01-01

    This paper constructs a general equilibrium search-matching model with heterogeneous workers. Workers choose whether to invest in general human capital or specific human capital when they enter the labor market. We analyze how unemployment benefits affect the choice of the type of human capital investment.

  6. Chemical Emergencies

    Science.gov (United States)

    When a hazardous chemical has been released, it may harm people's health. Chemical releases can be unintentional, as in the case of an ... the case of a terrorist attack with a chemical weapon. Some hazardous chemicals have been developed by ...

  7. An analysis of the concept of equilibrium in organization theory

    OpenAIRE

    Gazendam, Henk W.M.; Simons, John L.

    1998-01-01

    This article analyzes how the equilibrium concept is used in four organization theories: the theories of Fayol, Mintzberg, Morgan, and Volberda. Equilibrium can be defined as balance, fit or requisite variety. Equilibrium is related to observables dependent on the definition of organization as work organization, formal organization or artifact organization. The discussed theories can be mapped on a state space model in a way that clarifies the equilibrium concept. The equilibrium concept in o...

  8. Local thermal equilibrium of dense baryonic matter at CBM experiment

    International Nuclear Information System (INIS)

    The Compressed Baryonic Matter (CBM) experiment at FAIR/GSI laboratory is being designed to perform heavy-ion collisions in fixed target mode at beam energies of 5-45 GeV per nucleon. The major scientific issues addressed in the experiment are the properties of quantum chromodynamics (QCD) at high baryon density and moderate temperature and the order of quark-hadron phase transition at large baryo-chemical potential. However an important question arises whether the dense baryonic matter created in such collisions may achieve a local thermal equilibrium or not. We have investigated the conditions of local thermal equilibrium of baryons and mesons in a small element of volume within the rapidity range |y| <1.0 for central Au+Au collisions at Elab = 10, 20, 30, 40 GeV per nucleon. For this purpose we used the microscopic transport model UrQMD-3.3 in default cascade mode. We calculated the longitudinal-to-transverse pressure anisotropy (PL/PT) and the inverse slope parameter of energy spectra of baryons and mesons inside the cell at different times (t)= 1-15 fm/c measured in center of mass frame. The quantities are averaged over 60 K events at every time step

  9. Application of non-equilibrium plasmas in medicine

    Directory of Open Access Journals (Sweden)

    Mojsilović S.

    2012-01-01

    Full Text Available We review the potential of plasma medical applications, the connections to nanotechnologies and the results obtained by our group. A special issue in plasma medicine is the development of the plasma sources that would achieve non-equilibrium at atmospheric pressure in atmospheric gas mixture with no or only marginal heating of the gas, and with desired properties and mechanisms that may be controlled. Our studies have shown that control of radicals or chemically active products of the discharge such as ROS (reactive oxygen species and/or NO may be used to control the growth of the seeds. At the same time specially designed plasma needle and other sources were shown to be efficient to sterilize not only colonies of bacteria but also planctonic samples (microorganisms protected by water or bio films. Finally we have shown that plasma may induce differentiation of stem cells. Non-equilibrium plasmas may be used in detection of different specific markers in medicine. For example proton transfer mass spectroscopy may be employed in detection of volatile organic compounds without their dissociation and thus as a technique for instantaneous measurement of the presence of markers for numerous diseases. [Projekat Ministarstva nauke Republike Srbije, br. ON171037 i br. III41011

  10. Effective equilibrium theory of nonequilibrium quantum transport

    International Nuclear Information System (INIS)

    The theoretical description of strongly correlated quantum systems out of equilibrium presents several challenges and a number of open questions persist. Here, we focus on nonlinear electronic transport through an interacting quantum dot maintained at finite bias using a concept introduced by Hershfield [S. Hershfield, Phys. Rev. Lett. 70 2134 (1993)] whereby one can express such nonequilibrium quantum impurity models in terms of the system's Lippmann-Schwinger operators. These scattering operators allow one to reformulate the nonequilibrium problem as an effective equilibrium problem associated with a modified Hamiltonian. In this paper, we provide a pedagogical analysis of the core concepts of the effective equilibrium theory. First, we demonstrate the equivalence between observables computed using the Schwinger-Keldysh framework and the effective equilibrium approach, and relate Green's functions in the two theoretical frameworks. Second, we expound some applications of this method in the context of interacting quantum impurity models. We introduce a novel framework to treat effects of interactions perturbatively while capturing the entire dependence on the bias voltage. For the sake of concreteness, we employ the Anderson model as a prototype for this scheme. Working at the particle-hole symmetric point, we investigate the fate of the Abrikosov-Suhl resonance as a function of bias voltage and magnetic field. - Highlights: → Reformulation of steady-state nonequilibrium quantum transport, following Hershfield. → Derivation of effective equilibrium density operator using the 'open-system' approach. → Equivalence with the Keldysh description and formulas relating the two approaches. → Novel framework to treat interactions perturbatively. → Application to nonequilibrium Anderson model and fate of Abrikosov-Suhl resonance.

  11. Proceedings of RIKEN BNL research center workshop, equilibrium and non-equilibrium aspects of hot, dense QCD, Vol. 28

    International Nuclear Information System (INIS)

    The Relativistic Heavy Ion Collider (RHIC) at Brookhaven, beginning operation this year, and the Large Hadron Collider (LHC) at CERN, beginning operation ∼2005, will provide an unprecedented range of energies and luminosities that will allow us to probe the Gluon-Quark plasma. At RHIC and LHC, at central rapidity typical estimates of energy densities and temperatures are e * 1-10 GeV/fm3 and T0 * 300 - 900 MeV. Such energies are well above current estimates for the GQ plasma. Initially, this hot, dense plasma is far from local thermal equilibrium, making the theoretical study of transport phenomena, kinetic and chemical equilibration in dense and hot plasmas, and related issues a matter of fundamental importance. During the last few years a consistent framework to study collective effects in the Gluon-Quark plasma, and a microscopic description of transport in terms of the hard thermal (and dense) loops resummation program has emerged. This approach has the potential of providing a microscopic formulation of transport, in the regime of temperatures and densities to be achieved at RHIC and LHC. A parallel development over the last few years has provided a consistent formulation of non-equilibrium quantum field theory that provides a real-time description of phenomena out of equilibrium. Novel techniques including non-perturbative approaches and the dynamical renormalization group techniques lead to new insights into transport and relaxation. A deeper understanding of collective.excitations and transport phenomena in the GQ plasma could lead to recognize novel potential experimental signatures. New insights into small-c physics reveals a striking similarity between small-c and hard thermal loops, and novel real-time numerical simulations have recently studied the parton distributions and their thermalizations in the initial stages of a heavy ion collision

  12. Standardization of 125 Sb in equilibrium non-equilibrium situations with 125m Te

    International Nuclear Information System (INIS)

    We study the stability of ''125 Sb in the following scintillators: HiSafeIII''TM, Insta- Gel regsign Plus and '' Ultima-Gold'' TM. Since ''125 m Te requires more than one year to reach the secular equilibrium with ''125 Sb, we cannot be sure, for a given sample, whether equilibrium is reached or not. In this report we present a new procedure that permits one calibrate mixtures of ''125 Sb+''125 m Te out of the equilibrium. The steps required for the radiochemical separation of the components are indicated. Finally, we study the evolution of counting rate when column yields are less than 100%. (Author)

  13. SOLGAS refined: A computerized thermodynamic equilibrium calculation tool

    International Nuclear Information System (INIS)

    SOLGAS, an early computer program for calculating equilibrium in a chemical system, has been made more user-friendly, and several open-quote bells and whistlesclose quotes have been added. The necessity to include elemental species has been eliminated. The input of large numbers of starting conditions has been automated. A revised format for entering data simplifies and reduces chances for error. Calculated errors by SOLGAS are flagged, and several programming errors are corrected. Auxiliary programs are available to assemble and partially automate plotting of large amounts of data. Thermodynamic input data can be changed open-quotes on line.close-quote The program can be operated with or without a co-processor. Copies of the program, suitable for the IBM-PC or compatible with at least 384 bytes of low RAM, are available from the authors

  14. Photoionized gas in hydrostatic equilibrium: the role of gravity

    CERN Document Server

    Ascasibar, Y

    2010-01-01

    We present a method to include the effects of gravity in the plasma physics code Cloudy. More precisely, a term is added to the desired gas pressure in order to enforce hydrostatic equilibrium, accounting for both the self-gravity of the gas and the presence of an optional external potential. As a test case, a plane-parallel model of the vertical structure of the Milky Way disk near the solar neighbourhood is considered. It is shown that the gravitational force determines the scale height of the disk, and it plays a critical role in setting its overall chemical composition. However, other variables, such as the shape of incident continuum and the intensity of the Galactic magnetic field, strongly affect the predicted structure.

  15. Equilibrium and Disequilibrium Chemistry in Evolved Exoplanet Atmospheres

    Science.gov (United States)

    Hu, Renyu

    2015-12-01

    It has been found that sub-Neptune-sized planets, although not existing in our Solar System, are ubiquitous in our interstellar neighborhood. This revelation is profound because, due to their special sizes and proximity to their host stars, Neptune- and sub-Neptune-sized exoplanets may have highly evolved atmospheres. I will discuss helium-dominated atmospheres as one of the outcomes of extensive atmospheric evolution on warm Neptune- and sub-Neptune-sized exoplanets. Due to depleted hydrogen abundance, the dominant carbon and oxygen species may not be methane or water on these evolved planets. Equilibrium and disequilibrium chemistry models are used to compute the molecular compositions of the atmospheres and their spectral features. Applications to GJ 436 b and other Neptune- and sub-Neptune-sized exoplanets will be discussed. As the observations to obtain the spectra of these planets continue to flourish, we will have the opportunity to study unconventional atmospheric chemical processes and test atmosphere evolution theories

  16. Consistent vapour-liquid equilibrium data containing lipids

    DEFF Research Database (Denmark)

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

    Consistent physical and thermodynamic properties of pure components and their mixtures are important for process design, simulation, and optimization as well as design of chemical based products. In the case of lipids, it was observed a lack of experimental data for pure compounds and also for...... their mixtures in open literature, what makes necessary the development of reliable predictive models based on limited data. To contribute to the missing data, measurements of isobaric vapour-liquid equilibrium (VLE) data of three binary mixtures at two different pressures were performed at State...... distillates while systems 2 and 3 are relevant in the purification steps of biodiesel and bioglycerin. It should be highlighted that there is no such data in the open literature, not only for the specific compounds we selected but also for the combination of the classes of compounds considered in this work...

  17. Non-equilibrium CO chemistry in the solar atmosphere

    CERN Document Server

    Ramos, A A; Carlsson, M; Cernicharo, J

    2003-01-01

    Investigating the reliability of the assumption of instantaneous chemical equilibrium (ICE) for calculating the CO number density in the solar atmosphere is of crucial importance for the resolution of the long-standing controversy over the existence of `cool clouds' in the chromosphere, and for determining whether the cool gas owes its existence to CO radiative cooling or to a hydrodynamical process. Here we report the first results of such an investigation in which we have carried out time-dependent gas-phase chemistry calculations in radiation hydrodynamical simulations of solar chromospheric dynamics. We show that while the ICE approximation turns out to be suitable for modeling the observed infrared CO lines at the solar disk center, it may substantially overestimate the `heights of formation' of strong CO lines synthesized close to the edge of the solar disk, especially concerning vigorous dynamic cases resulting from relatively strong photospheric disturbances. This happens because during the cool phase...

  18. Fate of polychlorinated biphenyls in a contaminated lake ecosystem: Combining equilibrium passive sampling of sediment and water with total concentration measurements of biota

    DEFF Research Database (Denmark)

    Mäenpää, Kimmo; Leppänen, Matti T.; Figueiredo, Kaisa;

    2015-01-01

    hydrophobic organic chemicals in biota lipids. The authors' aim was to assess the equilibrium status of polychlorinated biphenyls (PCBs) in a contaminated lake ecosystem and along its discharge course using equilibrium sampling devices for measurements in sediment and water and by also analyzing biota. The...... authors used equilibrium sampling devices (silicone rubber and polyethylene [PE]) to determine freely dissolved concentrations and chemical activities of PCBs in the water column and sediment porewater and calculated for both phases the corresponding equilibrium concentrations and chemical activities in...... model lipids. Overall, the studied ecosystem appeared to be in disequilibrium for the studied phases: sediment, water, and biota. Chemical activities of PCBs were higher in sediment than in water, which implies that the sediment functioned as a partitioning source of PCBs and that net diffusion occurred...

  19. Equilibrium and non-equilibrium dynamics simultaneously operate in the Galápagos islands.

    Science.gov (United States)

    Valente, Luis M; Phillimore, Albert B; Etienne, Rampal S

    2015-08-01

    Island biotas emerge from the interplay between colonisation, speciation and extinction and are often the scene of spectacular adaptive radiations. A common assumption is that insular diversity is at a dynamic equilibrium, but for remote islands, such as Hawaii or Galápagos, this idea remains untested. Here, we reconstruct the temporal accumulation of terrestrial bird species of the Galápagos using a novel phylogenetic method that estimates rates of biota assembly for an entire community. We show that species richness on the archipelago is in an ascending phase and does not tend towards equilibrium. The majority of the avifauna diversifies at a slow rate, without detectable ecological limits. However, Darwin's finches form an exception: they rapidly reach a carrying capacity and subsequently follow a coalescent-like diversification process. Together, these results suggest that avian diversity of remote islands is rising, and challenge the mutual exclusivity of the non-equilibrium and equilibrium ecological paradigms. PMID:26105791

  20. Selected readings in chemical kinetics

    CERN Document Server

    Back, Margaret H

    2013-01-01

    Selected Readings in Chemical Kinetics covers excerpts from 12 papers in the field of general and gas-phase kinetics. The book discusses papers on the laws of connexion between the conditions of a chemical change and its amount; on the reaction velocity of the inversion of the cane sugar by acids; and the calculation in absolute measure of velocity constants and equilibrium constants in gaseous systems. The text then tackles papers on simple gas reactions; on the absolute rate of reactions in condensed phases; on the radiation theory of chemical action; and on the theory of unimolecular reacti

  1. The equation of state and ionization equilibrium of dense aluminum plasma with conductivity verification

    International Nuclear Information System (INIS)

    The equation of state, ionization equilibrium, and conductivity are the most important parameters for investigation of dense plasma. The equation of state is calculated with the non-ideal effects taken into consideration. The electron chemical potential and pressure, which are commonly used thermodynamic quantities, are calculated by the non-ideal free energy and compared with results of a semi-empirical equation of state based on Thomas-Fermi-Kirzhnits model. The lowering of ionization potential, which is a crucial factor in the calculation of non-ideal Saha equation, is settled according to the non-ideal free energy. The full coupled non-ideal Saha equation is applied to describe the ionization equilibrium of dense plasma. The conductivity calculated by the Lee-More-Desjarlais model combined with non-ideal Saha equation is compared with experimental data. It provides a possible approach to verify the accuracy of the equation of state and ionization equilibrium

  2. Modelling asphaltene precipitation equilibrium : influence of the experimental contact time and temperature

    Energy Technology Data Exchange (ETDEWEB)

    Dufour, J.; Marugan, J.; Calles, J.A.; Gimenez-Aguirre, R. [Rey Juan Carlos Univ., Madrid (Spain). Dept. of Chemical and Environmental Technology, Repsol-YPF Flow Assurance Laboratory; Pena, J.L. [Rey Juan Carlos Univ., Madrid (Spain). Dept. of Chemical and Environmental Technology, Repsol-YPF Flow Assurance Laboratory; Centro Tecnologico Repsol-YPF, Madrid (Spain); Merino-Garcia, D. [Centro Tecnologico Repsol-YPF, Madrid (Spain)

    2008-07-01

    Asphaltene deposition creates flow assurance problems and economic losses for petroleum companies. Predictive models are therefore needed to prevent these problems. Most models found in the literature are based on equilibrium calculations and must be checked against experimental data of both onset and amount of asphaltenes separated. However, the samples must be equilibrated for a long time since the kinetics of asphaltene aggregation and precipitation are slow. This paper discussed the kinetics of asphaltene precipitation, based on results obtained from a problematic South American crude and its residue. The influence of temperature, chain length of the n-alkane solvent and n-alkane/oil mass ratio was evaluated. The solids were characterized by 1H NMR, elemental analysis and Fourier transform infrared (FTIR) spectroscopy to determine their chemical structure. Metal contents (mainly Fe, V and Ni) have been measured by atomic emission spectroscopy. The true equilibrium data will be used to validate equilibrium models from the literature.

  3. Copper adsorption on magnetite-loaded chitosan microspheres: A kinetic and equilibrium study

    Energy Technology Data Exchange (ETDEWEB)

    Podzus, P.E., E-mail: ppodzus@gmail.com [Grupo de Aplicaciones de Materiales Biocompatibles, Departamento de Quimica, Facultad de Ingenieria, Universidad de Buenos Aires, Paseo Colon 850, C1063ACV Buenos Aires (Argentina); Debandi, M.V. [Grupo de Aplicaciones de Materiales Biocompatibles, Departamento de Quimica, Facultad de Ingenieria, Universidad de Buenos Aires, Paseo Colon 850, C1063ACV Buenos Aires (Argentina); Daraio, M.E., E-mail: medit@fi.uba.ar [Grupo de Aplicaciones de Materiales Biocompatibles, Departamento de Quimica, Facultad de Ingenieria, Universidad de Buenos Aires, Paseo Colon 850, C1063ACV Buenos Aires (Argentina)

    2012-08-15

    A composite of Fe{sub 3}O{sub 4} nanoparticles and the biopolymer chitosan, chemically crosslinked, was prepared as microspheres and used to adsorb copper ions, which were chosen as a model of contaminant metal in water. The adsorption of copper on the magnetic microspheres was studied in a batch process, with different aqueous solutions of Cu (II) at concentrations ranging from 40 to 1100 ppm. Kinetic and equilibrium aspects of the adsorption process were studied. The time-dependent Cu (II) adsorption data were well described by a pseudo-second-order kinetic model. It was found that the equilibrium data follow the Langmuir isotherm, with a maximum adsorption capacity of around 500 mg Cu/g chitosan. The used microspheres were removed and after desorption the material was able to be reused as an adsorbent. The prepared microspheres proved efficient in the removal of copper ions through an adsorption process whose kinetic and equilibrium characteristics were analyzed.

  4. Equilibrium and stability of a rotating plasma

    International Nuclear Information System (INIS)

    The author considers the equilibrium and stability of a rotating plasma. The kinetic equations for ions and electrons supplemented with the Maxwell equations and the appropriate boundary conditions are used. Two different models for the rotating plasma are considered: the equilibrium of a 'fast' rotating plasma (Magneto Hydrodynamic ordering) and the stability of a slowly rotating, 'weakly' unstable plasma (Finite Larmor Radius ordering). A striking difference between these orderings is the fact that, regarding the stability of the plasma, for a F.L.R. plasma viscosity effects due to the finite Larmor radius are important, whereas in a M.H.D. plasma they are negligible (at least to the required order). (Auth.)

  5. An equilibrium approach to modelling social interaction

    CERN Document Server

    Gallo, Ignacio

    2009-01-01

    The aim of this work is to put forward a statistical mechanics theory of social interaction, generalizing econometric discrete choice models. After showing the formal equivalence linking econometric multinomial logit models to equilibrium statical mechanics, a multi-population generalization of the Curie-Weiss model for ferromagnets is considered as a starting point in developing a model capable of describing sudden shifts in aggregate human behaviour. Existence of the thermodynamic limit for the model is shown by an asymptotic sub-additivity method and factorization of correlation functions is proved almost everywhere. The exact solution of the model is provided in the thermodynamical limit by finding converging upper and lower bounds for the system's pressure, and the solution is used to prove an analytic result regarding the number of possible equilibrium states of a two-population system. The work stresses the importance of linking regimes predicted by the model to real phenomena, and to this end it propo...

  6. Punctuated equilibrium in a neontological context.

    Science.gov (United States)

    Monroe, Melanie J; Bokma, Folmer

    2010-09-01

    The theory of punctuated equilibrium, which proposes that biological species evolve rapidly when they originate rather than gradually over time, has sparked intense debate between palaeontologists and evolutionary biologists about the mode of character evolution and the importance of natural selection. Difficulty in interpreting the fossil record prevented consensus, and it remains disputed as to what extent gradual change in established species is responsible for phenotypic differences between species. Against the historical background of the concept of evolution concentrated in speciation events, we review attempts to investigate tempo and mode of evolution using present-day species since the introduction of the theory of punctuated equilibrium in 1972. We discuss advantages, disadvantages, and prospects of using neontological data, methodological advances, and the findings of some recent studies. PMID:20514523

  7. Equilibrium fluctuation theorems compatible with anomalous response

    Science.gov (United States)

    Velazquez, L.; Curilef, S.

    2010-12-01

    Previously, we have derived a generalization of the canonical fluctuation relation between heat capacity and energy fluctuations C = β2langδU2rang, which is able to describe the existence of macrostates with negative heat capacities C < 0. In this work, we extend our previous results for an equilibrium situation with several control parameters to account for the existence of states with anomalous values in other response functions. Our analysis leads to the derivation of three different equilibrium fluctuation theorems: the fundamental and the complementary fluctuation theorems, which represent the generalization of two fluctuation identities already obtained in previous works, and the associated fluctuation theorem, a result that has no counterpart in the framework of Boltzmann-Gibbs distributions. These results are applied to study the anomalous susceptibility of a ferromagnetic system, in particular, the case of the 2D Ising model.

  8. Equilibrium time correlation functions in open systems

    CERN Document Server

    Zhu, Jinglong; Agarwal, Animesh; Site, Luigi Delle

    2014-01-01

    We study equilibrium time correlation functions for liquid water at room temperature employing the Molecular Dynamics (MD) adaptive resolution method AdResS in its Grand Canonical formulation (GC-AdResS). This study introduces two technical innovations: the employment of a local thermostat that acts only in the reservoir and the consequent construction of an "ideal" Grand Canonical reservoir of particles and energy. As a consequence the artificial action of a thermostat in the calculation of equilibrium time correlation functions of standard NVT simulations is efficiently removed. The success of the technical innovation provides the basis for formulating a profound conceptual problem, that is the extension of Liouville theorem to open systems (Grand Canonical ensemble), a question, so far, treated neither in MD nor (in general) in statistical physics.

  9. Uncertainty Principle Consequences at Thermal Equilibrium

    CERN Document Server

    Pachon, Leonardo A; Zueco, David; Brumer, Paul

    2014-01-01

    Contrary to the conventional wisdom that deviations from standard thermodynamics originate from the strong coupling to the bath, it is shown that these deviations are intimately linked to the power spectrum of the thermal bath. Specifically, it is shown that the lower bound of the dispersion of the total energy of the system, imposed by the uncertainty principle, is dominated by the bath power spectrum and therefore, quantum mechanics inhibits the system thermal-equilibrium-state from being described by the canonical Boltzmann's distribution. This is in sharp contrast to the classical case, for which the thermal equilibrium distribution of a system interacting via central forces with pairwise-self-interacting environment, irrespective of the interaction strength, is shown to be \\emph{exactly} characterized by the canonical Boltzmann distribution. As a consequence of this analysis, we define an \\emph{effective coupling} to the environment that depends on all energy scales in the system and reservoir interactio...

  10. Equilibrium and stability of helical systems

    International Nuclear Information System (INIS)

    For the purpose of preparing basic data for designing a new large helical system, we have made a numerical survey of equilibrium and linear stabilities of l = 2 torsatron/heliotron. We try to find out optimum configuration in a wide parameter space where the coil aspect ratio γc is changed as well as the pitch period number M. We determine the parameter region within which a high β current-less plasma is obtained from the view points of both the equilibrium and stability limits. Moreover, we execute a sensitivity analysis of various parameters on the stability, such as the vertical field, the quadruple field, the pressure profile, the shape of the helical coil, and the pitch modulation. We find each parameter gives strong influence on the stability. (author)

  11. On equilibrium charge distribution above dielectric surface

    Directory of Open Access Journals (Sweden)

    Yu.V. Slyusarenko

    2009-01-01

    Full Text Available The problem of the equilibrium state of the charged many-particle system above dielectric surface is formulated. We consider the case of the presence of the external attractive pressing field and the case of its absence. The equilibrium distributions of charges and the electric field, which is generated by these charges in the system in the case of ideally plane dielectric surface, are obtained. The solution of electrostatic equations of the system under consideration in case of small spatial heterogeneities caused by the dielectric surface, is also obtained. These spatial inhomogeneities can be caused both by the inhomogeneities of the surface and by the inhomogeneous charge distribution upon it. In particular, the case of the "wavy" spatially periodic surface is considered taking into account the possible presence of the surface charges.

  12. Uniqueness of Nash equilibrium in vaccination games.

    Science.gov (United States)

    Bai, Fan

    2016-12-01

    One crucial condition for the uniqueness of Nash equilibrium set in vaccination games is that the attack ratio monotonically decreases as the vaccine coverage level increasing. We consider several deterministic vaccination models in homogeneous mixing population and in heterogeneous mixing population. Based on the final size relations obtained from the deterministic epidemic models, we prove that the attack ratios can be expressed in terms of the vaccine coverage levels, and also prove that the attack ratios are decreasing functions of vaccine coverage levels. Some thresholds are presented, which depend on the vaccine efficacy. It is proved that for vaccination games in homogeneous mixing population, there is a unique Nash equilibrium for each game. PMID:27465224

  13. Adaptive resolution simulation in equilibrium and beyond

    Science.gov (United States)

    Wang, H.; Agarwal, A.

    2015-09-01

    In this paper, we investigate the equilibrium statistical properties of both the force and potential interpolations of adaptive resolution simulation (AdResS) under the theoretical framework of grand-canonical like AdResS (GC-AdResS). The thermodynamic relations between the higher and lower resolutions are derived by considering the absence of fundamental conservation laws in mechanics for both branches of AdResS. In order to investigate the applicability of AdResS method in studying the properties beyond the equilibrium, we demonstrate the accuracy of AdResS in computing the dynamical properties in two numerical examples: The velocity auto-correlation of pure water and the conformational relaxation of alanine dipeptide dissolved in water. Theoretical and technical open questions of the AdResS method are discussed in the end of the paper.

  14. Equilibrium policies when preferences are time inconsistent

    CERN Document Server

    Ekeland, Ivar

    2008-01-01

    This paper characterizes differentiable and subgame Markov perfect equilibria in a continuous time intertemporal decision problem with non-constant discounting. Capturing the idea of non commitment by letting the commitment period being infinitesimally small, we characterize the equilibrium strategies by a value function, which must satisfy a certain equation. The equilibrium equation is reminiscent of the classical Hamilton-Jacobi-Bellman equation of optimal control, but with a non-local term leading to differences in qualitative behavior. As an application, we formulate an overlapping generations Ramsey model where the government maximizes a utilitarian welfare function defined as the discounted sum of successive generations' lifetime utilities. When the social discount rate is different from the private discount rate, the optimal command allocation is time inconsistent and we retain subgame perfection as a principle of intergenerational equity. Existence of multiple subgame perfect equilibria is establishe...

  15. Equilibrium Macroscopic Structure Revisited from Spatial Constraint

    Science.gov (United States)

    Yuge, Koretaka

    2016-02-01

    In classical systems, we reexamine how macroscopic structures in equilibrium state connect with spatial constraint on the systems. For example, volume and density as the constraint for liquids in rigid box, and crystal lattice as the constraint for crystalline solids. We find that in disordered states, equilibrium macroscopic structure, depending on temperature and on multibody interactions in the system, can be well characterized by a single special microscopic structure independent of temperature and of interactions. The special microscopic structure depends only on the spatial constraint. We demonstrate the present findings providing (i) significantly efficient and systematic prediction of macroscopic structures for possible combination of constituents in multicomponent systems using first-principles calculations, and (ii) unique and accurate prediction of multibody interactions in given system from measured macroscopic structure, without performing trial-and-error simulation.

  16. Fluctuations in Hertz chains at equilibrium

    CERN Document Server

    Przedborski, Michelle; Harroun, Thad A

    2016-01-01

    We examine the long-term behaviour of non-integrable, energy-conserved, 1D systems of macroscopic grains interacting via a contact-only generalized Hertz potential and held between stationary walls. Existing dynamical studies showed the absence of energy equipartitioning in such systems, hence their long-term dynamics was described as quasi-equilibrium. Here we show that, if spatial symmetry is broken, these systems do in fact reach thermal equilibrium as time $t \\to \\infty$, as indicated by the calculated heat capacity. As a byproduct, we show how fluctuations of system quantities, and thus the distribution functions, are influenced by the Hertz potential. In particular, the variance of the system's kinetic energy probability density function is reduced by a factor related to the contact potential.

  17. A Punctuated Equilibrium in French Budgeting Processes

    OpenAIRE

    B. Baumgartner, Frank; Foucault, Martial; François, Abel

    2006-01-01

    We use data on French budgeting to test models of friction, incrementalism and punctuated equilibrium. Data include the overall state budget since 1820; ministerial budgets for seven ministries since 1868; and a more complete ministerial series covering ten ministries since 1947. Our results in every case are remarkably similar to the highly leptokurtic distributions that Jones and Baumgartner (2005) demonstrated in US budgeting processes. This suggests that general characteristics of adminis...

  18. A Central Limit Theorem for Punctuated Equilibrium

    OpenAIRE

    Bartoszek, Krzysztof

    2016-01-01

    Current evolutionary biology models usually assume that a phenotype undergoes gradual change. This is in stark contrast to biological intuition, which indicates that change can also be punctuated - the phenotype can jump. Such a jump can especially occur at speciation, i.e. dramatic change occurs that drives the species apart. Here we derive a central limit theorem for punctuated equilibrium. We show that, if adaptation is fast, for weak convergence to hold, dramatic change has to be a rare e...

  19. Computing Cournot Equilibrium through Maximization over Prices

    OpenAIRE

    Orbay, Hakan

    2007-01-01

    This paper presents an alternative characterization of internal Cournot equilibrium based on the first-order conditions corresponding to profit maximization over prices. This characterization is particularly useful when the market is described in terms of demand functions (rather than inverse-demand functions). A significant computational advantage is gained in homogeneous good cases as demand functions need not be inverted and simple first order conditions are obtained. ...

  20. Vapour liquid equilibrium measurements for process design

    OpenAIRE

    Uusi-Kyyny, Petri

    2004-01-01

    In recent years it has become increasingly important to develop new oxygenate and isooctane technologies and processes that meet the continuously stricter environmental requirements. Some of the new process schemes use renewable raw materials in order to meet the European Union biofuel requirements. One of the most important requirements for the design of such separation processes includes the knowledge of vapour liquid equilibrium (VLE) behaviour. There are methods to estimate VLE but for th...

  1. A Cubic Micron of Equilibrium Pair Plasma?

    OpenAIRE

    Katz, J. I.

    1998-01-01

    Is it possible to create a small volume of equilibrium pair plasma in the laboratory with an intense laser pulse? No. The required power would exceed 10^{18} W. The number of seed particles required to absorb the laser energy would approach the number of pairs in the desired plasma, and their radiation in a visible laser field would occur at extremely high frequencies.

  2. Modeling Growing Economies in Equilibrium and Disequilibrium

    OpenAIRE

    Kelley, A C; W.C. Sanderson; Williamson, J. G.

    1983-01-01

    The papers in this volume were presented and discussed at a meeting held at IIASA. The meeting's goals were to stimulate interaction and collaboration, and to encourage setting research priorities for the future. Indeed, it is in this latter area where the meeting appeared to yield some of its greatest benefits. It became clear from the deliberations that much needs to be done to better specify the microfoundations of general equilibrium models. More realistic specifications of "conflict...

  3. Equilibrium Asset Prices Under Imperfect Corporate Control

    OpenAIRE

    James Dow; Gary Gorton; Arvind Krishnamurthy

    2003-01-01

    Shareholders have imperfect ontrol over the decisions of the management of a firm. We integrate a widely accepted version of the separation of ownership and control -- Jensen's (1986) free cash flow theory--into a dynamic equilibrium model and study the effect of imperfect corporate control on asset prices and investment. We assume that firms are run by empire-building managers who prefer to invest all free cash flow rather than distributing it to shareholders. Sharefholders are aware of this...

  4. Factor Markets in General Computable Equilibrium Models

    OpenAIRE

    Banse, Martin; Shutes, Lindsay; Dixon, Peter; van Meijl, Hans; Rimmer, Maureen; Tabeau, Andrzej; Geert WOLTJER; Rothe, Andrea

    2013-01-01

    One objective of Computable general equilibrium (CGE) models is the analysis of economy-wide effects of policy measures. The focus of the Factor Markets project is to analyse the functioning of factor markets for agriculture in the EU-27, including the Candidate Countries. While agricultural and food markets are fully integrated in a European single market, subject to an EU-wide common policy, the Common Agricultural Policy (CAP), this is not the case for the agricultural factor markets capit...

  5. Data issues in general equilibrium modelling

    OpenAIRE

    Beutre, Benjamin; Rodriguez, Gil; Hom M. Pant

    2003-01-01

    In recent years global general equilibrium (GE) models have been used to analyse policy issues such as trade liberalisation, regional integration and environmental policies. While a global CGE model is an excellent tool to perform a comprehensive analysis of such policies, it requires an enormous amount of data to calibrate or parameterise the model itself. Quality differences in the data sets might affect the results of the model simulation. Identifying and removing problems in the database ...

  6. Non-equilibrium thermodynamics of gravitational screens

    OpenAIRE

    Freidel, Laurent; Yokokura, Yuki

    2014-01-01

    We study the Einstein gravity equations projected on a timelike surface, which represents the time evolution of what we call a gravitational screen. We show that such a screen behaves like a viscous bubble with a surface tension and an internal energy, and that the Einstein equations take the same forms as non-equilibrium thermodynamic equations for a viscous bubble. We provide a consistent dictionary between gravitational and thermodynamical variables. In the non-viscous cases there are thre...

  7. Equilibrium analysis, banking, contagion and financial fragility

    OpenAIRE

    Tsomocos, Dimitrios P.

    2003-01-01

    This paper contains a General Equilibrium model of an economy with Incomplete Markets (GEI) with money and default. The model is a simplified version of the real world consisting of a non-bank private sector, banks, a Central Bank, a government and a regulator. The model is used to analyse actions by policy makers and to identify policy relevant empirical work. Key analytical results are: A financially fragile system need not collapse; efficiency can be improved with policy intervention; and ...

  8. The general equilibrium theory as economic metatheory

    OpenAIRE

    MAURICIO MARTINELLI LUPERI

    2015-01-01

    Many economists show certain nonconformity relative to the excessive mathematical formalization of economics. This stems from dissatisfaction with the old debate about the lack of correspondence between mainstream theoretical models and reality. Although we do not propose to settle this debate here, this article seeks to associate the mismatch of mathematized models with the reality of the adoption of the hypothetical-deductive method as reproduced by general equilibrium. We begin by defining...

  9. Bifurcated Helical Core Equilibrium States in Tokamaks

    International Nuclear Information System (INIS)

    Full text: Tokamaks with weak to moderate reversed central magnetic shear in which the minimum of the inverse rotational transform qmin is in the neighbourhood of unity can trigger bifurcated MagnetoHydroDynamic (MHD) equilibrium states. In addition to the standard axisymmetric branch that can be obtained with standard Grad-Shafranov solvers, a novel branch with a three-dimensional (3D) helical core has been computed with the ANIMEC code, an anisotropic pressure extension of the VMEC code. The solutions have imposed nested magnetic flux surfaces and are similar to saturated ideal internal kink modes. The difference in energy between both possible branches is very small. Plasma elongation, current and β enhance the susceptibility for bifurcations to occur. An initial value nonlinear ideal MHD evolution of the axisymmetric branch compares favourably with the helical core equilibrium structures calculated. Peaked prescribed pressure profiles reproduce the 'snake' structures observed in many tokamaks which has led to a new explanation of the snake as a bifurcated helical equilibrium state that results from a saturated ideal internal kink in which pellets or impurities induce a hollow current profile. Snake equilibrium structures are computed in free boundary TCV tokamak simulations. Magnetic field ripple and resonant magnetic perturbations in MAST free boundary calculations do not alter the helical core deformation in a significant manner when qmin is near unity. These bifurcated solutions constitute a paradigm shift that motivates the application of tools developed for stellarator research in tokamak physics investigations. The examination of fast ion confinement in this class of equilibria is performed with the VENUS code in which a coordinate independent noncanonical phase-space Lagrangian formulation of guiding centre drift orbit theory has been implemented. (author)

  10. Regret Theory and Equilibrium Asset Prices

    OpenAIRE

    Jiliang Sheng; Jian Wang; Jun Yang

    2014-01-01

    Regret theory is a behavioral approach to decision making under uncertainty. In this paper we assume that there are two representative investors in a frictionless market, a representative active investor who selects his optimal portfolio based on regret theory and a representative passive investor who invests only in the benchmark portfolio. In a partial equilibrium setting, the objective of the representative active investor is modeled as minimization of the regret about final wealth relativ...

  11. Nanostructured energy devices equilibrium concepts and kinetics

    CERN Document Server

    Bisquert, Juan

    2014-01-01

    Due to the pressing needs of society, low cost materials for energy devices have experienced an outstanding development in recent times. In this highly multidisciplinary area, chemistry, material science, physics, and electrochemistry meet to develop new materials and devices that perform required energy conversion and storage processes with high efficiency, adequate capabilities for required applications, and low production cost. Nanostructured Energy Devices: Equilibrium Concepts and Kinetics introduces the main physicochemical principles that govern the operation of energy devices. It inclu

  12. A strictly hyperbolic equilibrium phase transition model

    Energy Technology Data Exchange (ETDEWEB)

    Allaire, G [Ecole Polytech, CNRS, CMAP, F-91128 Palaiseau (France); Faccanoni, G; Kokh, S. [CEA Saclay, DEN, DANS, DM2S, F-91191 Gif Sur Yvette, (France)

    2007-01-15

    This Note is concerned with the strict hyperbolicity of the compressible Euler equations equipped with an equation of state that describes the thermodynamical equilibrium between the liquid phase and the vapor phase of a fluid. The proof is valid for a very wide class of fluids. The argument only relies on smoothness assumptions and on the classical thermodynamical stability assumptions, that requires a definite negative Hessian matrix for each phase entropy as a function of the specific volume and internal energy. (authors)

  13. Immigration and Outsourcing: A General Equilibrium Analysis

    OpenAIRE

    Subhayu Bandoyopadhyay; Wall, Howard J.

    2005-01-01

    This paper analyzes the issues of immigration and outsourcing in a general-equilibrium model of international factor mobility. In our model, legal immigration is controlled through a quota, while outsourcing is determined both by the firms (in response to market conditions) and through policy-imposed barriers. A loosening of the immigration quota reduces outsourcing, enriches capitalists, leads to losses for native workers, and raises national income. If the nation targets an exogenously dete...

  14. Three terminal non-equilibrium superconducting devices

    International Nuclear Information System (INIS)

    I review various non-equilibrium three terminal superconducting devices. The Quiteron, while initially promising, has major failings that make it uncompetitive as a high speed three terminal device. By examining alternatives to the Quiteron structure we come to the conclusion that a quasiparticle injected microstrip device somewhat similar in concept to the original CLINK device of Wong et al. has considerable promise, provided that a low carrier density superconductor is employed as the microstrip material. (orig./BUD)

  15. Asset Market Equilibrium with Short-Selling.

    OpenAIRE

    Nielsen, Lars Tyge

    1989-01-01

    This paper presents simple conditions and a simple proof of the existence of equilibrium in asset markets where short-selling is allowed and satiation is possible. Unlike standard nonsatiation assumptions, the one used here is weak enough to be reasonable in the mean-variance capital asset pricing model and in asset market models where investors maximize expected utility and where total returns to individual assets may be negative. Copyright 1989 by The Review of Economic Studies Limited.

  16. On the Equilibrium of Simplicial Masonry Structures

    OpenAIRE

    de Goes, Fernando; Alliez, Pierre; Owhadi, Houman; Desbrun, Mathieu

    2013-01-01

    We present a novel approach for the analysis and design of selfsupporting simplicial masonry structures. A finite-dimensional formulation of their compressive stress field is derived, offering a new interpretation of thrust networks through numerical homogenization theory. We further leverage geometric properties of the resulting force diagram to identify a set of reduced coordinates characterizing the equilibrium of simplicial masonry. We finally derive computational form-finding tools that ...

  17. Uniform convergence to equilibrium for granular media

    CERN Document Server

    Bolley, François; Guillin, Arnaud

    2012-01-01

    We study the long time asymptotics of a nonlinear, nonlocal equation used in the modelling of granular media. We prove a uniform exponential convergence to equilibrium for degenerately convex and non convex interaction or confinement potentials, improving in particular results by J. A. Carrillo, R. J. McCann and C. Villani. The method is based on studying the dissipation of the Wasserstein distance between a solution and the steady state.

  18. Input and output inventories in general equilibrium

    OpenAIRE

    Iacoviello, Matteo; SCHIANTARELLI, FABIO; Schuh, Scott

    2007-01-01

    We build and estimate a two-sector (goods and services) dynamic stochastic general equilibrium model with two types of inventories: materials (input) inventories facilitate the production of finished goods, while finished goods (output) inventories yield utility services. The model is estimated using Bayesian methods. The estimated model replicates the volatility and cyclicality of inventory investment and inventory-to-target ratios. Although inventories are an important element of the model'...

  19. The mathematical description of equilibrium bipedal locomotion

    OpenAIRE

    Ткач, Михайло Мартинович

    2012-01-01

     This paper analyzes the current state of the construction of anthropomorphic walking machines. The areas of their future implementation. The basis of the publication is to define the criteria for compliance with the unstable equilibrium of walking aids by anthropic simulation. In particular, it provides a formalized solution to strike a balance on the surfaces of the second kind on the basis of observations of the center of mass displacement of the projection apparatus on the specified surfa...

  20. Bertrand Equilibrium in a Differentiated Duopoly.

    OpenAIRE

    1992-01-01

    This paper studies the stability of price competition in a horizontally differentiated duopoly. The firms' demand is derived from a distribution of consumer preferences. This description of the consumer sector is applicable to a large class of differentiated commodity markets, including spatial competition models. The author shows that there is a (pure) price-setting equilibrium when consumer tastes are sufficiently dispersed. Further conditions on the dispersedness of preferences guarantee u...