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Eric W Lemmon - One of the best experts on this subject based on the ideXlab platform.
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fundamental Equations of State for parahydrogen normal hydrogen and orthohydrogen
Journal of Physical and Chemical Reference Data, 2009Co-Authors: Jacob Leachman, R T Jacobsen, S G Penoncello, Eric W LemmonAbstract:If the potential for a boom in the global hydrogen economy is realized, there will be an increase in the need for accurate hydrogen thermodynamic property standards. Based on current and anticipated needs, new fundamental Equations of State for parahydrogen, normal hydrogen, and orthohydrogen were developed to replace the existing property models. To accurately predict thermophysical properties near the critical region and in liquid States, the quantum law of corresponding States was applied to improve the normal hydrogen and orthohydrogen formulations in the absence of available experimental data. All three Equations of State have the same maximum pressure of 2000MPa and upper temperature limit of 1000K. Uncertainty estimates in this paper can be considered to be estimates of a combined expanded uncertainty with a coverage factor of 2 for primary data sets. The uncertainty in density is 0.04% in the region between 250 and 450K and at pressures up to 300MPa. The uncertainties of vapor pressures and satura...
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multiparameter Equations of State for selected siloxanes
Fluid Phase Equilibria, 2006Co-Authors: Piero Colonna, Alberto Guardone, N R Nannan, Eric W LemmonAbstract:Abstract This article presents the development of technical Equations of State for four siloxanes using the 12-parameter Span–Wagner functional form. Siloxanes are used as heat transfer fluids and working media in energy conversion applications. The investigated fluids are two linear dimethylsiloxanes, namely MM (hexamethyldisiloxane, C6H18OSi2) and MD4M (tetradecamethylhexasiloxane, C14H42O5Si6), and two cyclic dimethylsiloxanes, namely D4 (octamethylcyclotetrasiloxane, C8H24O4Si4) and D5 (decamethylcyclopentasiloxane, C10H30O5Si5). Available measured properties are critically evaluated and selected for the optimization of the equation of State (EoS) parameters. Due to the insufficient number of experimental values, several other properties are estimated with the most accurate ad hoc methods. These estimates are included in the optimization of the equation of State parameters. Moreover, experimental saturated liquid density and vapor pressure data are correlated with the Equations proposed by Daubert and Wagner–Ambrose, respectively, to provide short, simple, and accurate Equations for the computation of these properties. The performance of the obtained Equations of State is assessed by comparison with experimental data and also with estimates obtained with the Peng–Robinson cubic EoS with the modification proposed by Stryjek and Vera. This equation was adopted in previous technical studies. The improvements obtained with the newly developed EoS's are significant. Exemplary State diagrams are also reported as a demonstration of the consistency of the obtained thermodynamic models. Sound speed measurements in the vapor phase are planned for the near future and results will be incorporated in future improvements of the newly developed thermodynamic models.
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short fundamental Equations of State for 20 industrial fluids
Journal of Chemical & Engineering Data, 2006Co-Authors: Eric W Lemmon, Roland SpanAbstract:In a preceding project, functional forms for “short” Helmholtz energy Equations of State for typical nonpolar and weakly polar fluids and for typical polar fluids were developed using simultaneous optimization. In this work, the coefficients of these short forms for the Equations of State have been fitted for the fluids acetone, carbon monoxide, carbonyl sulfide, decane, hydrogen sulfide, 2-methylbutane (isopentane), 2,2-dimethylpropane (neopentane), 2-methylpentane (isohexane), krypton, nitrous oxide, nonane, sulfur dioxide, toluene, xenon, hexafluoroethane (R-116), 1,1-dichloro-1-fluoroethane (R-141b), 1-chloro-1,1-difluoroethane (R-142b), octafluoropropane (R-218), 1,1,1,3,3-pentafluoropropane (R-245fa), and fluoromethane (R-41). The 12 coefficients of the Equations of State were fitted to substance specific data sets. The results show that simultaneously optimized functional forms can be applied to other fluids out of the same class of fluids for which they were optimized without significant loss of a...
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a new functional form and new fitting techniques for Equations of State with application to pentafluoroethane hfc 125
Journal of Physical and Chemical Reference Data, 2005Co-Authors: Eric W Lemmon, R T JacobsenAbstract:A widely used form of an equation of State explicit in Helmholtz energy has been modified with new terms to eliminate certain undesirable characteristics in the two phase region. Modern multiparameter Equations of State exhibit behavior in the two phase that is inconsistent with the physical behavior of fluids. The new functional form overcomes this dilemma and results in Equations of State for pure fluids that are more fundamentally consistent. With the addition of certain nonlinear fitting constraints, the new equation now achieves proper phase stability, i.e., only one solution exists for phase equilibrium at a given State. New fitting techniques have been implemented to ensure proper extrapolation of the equation at low temperatures, in the vapor phase at low densities, and at very high temperatures and pressures. A formulation is presented for the thermodynamic properties of refrigerant 125 (pentafluoroethane, CHF2–CF3) using the new terms and fitting techniques. The equation of State is valid for te...
Yoshiharu Eriguchi - One of the best experts on this subject based on the ideXlab platform.
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dynamical bar mode instability of differentially rotating stars effects of Equations of State and velocity profiles
Monthly Notices of the Royal Astronomical Society, 2003Co-Authors: Masaru Shibata, Shigeyuki Karino, Yoshiharu EriguchiAbstract:As an extension of our previous work, we investigate the dynamical instability against nonaxisymmetric bar-mode deformations of differentially rotating stars in Newtonian gravity by varying the Equations of State and velocity profiles. We performed the numerical simulation and the follow-up linear stability analysis by adopting polytropic Equations of State with polytropic indices n = 1, 3/2 and 5/2, and with two types of angular velocity profiles (the so-called j-constant-like and Kepler-like laws). It is confirmed that rotating stars with a high degree of differential rotation are dynamically unstable against bar-mode deformation, even when the ratio of the kinetic energy to the gravitational potential energy β is of order 0.01. The criterion for the onset of bar-mode dynamical instability depends weakly on the polytropic index n and the angular velocity profile, as long as the degree of differential rotation is high. Gravitational waves from the final non-axisymmetric quasi-stationary States are calculated using the quadrupole formula. For proto-neutron stars of mass 1.4 M� , radius ∼30 km and β 0.1, such gravitational waves have a frequency of ∼600‐1400 Hz, and the effective amplitude is larger than 10 −22 at a distance of about 100 Mpc, irrespective of n and the angular
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dynamical bar mode instability of differentially rotating stars effects of Equations of State and velocity profiles
arXiv: Astrophysics, 2003Co-Authors: Masaru Shibata, Shigeyuki Karino, Yoshiharu EriguchiAbstract:As an extension of our previous work, we investigate the dynamical instability against nonaxisymmetric bar-mode deformations of differentially rotating stars in Newtonian gravity varying the Equations of State and velocity profiles. We performed the numerical simulation and the followup linear stability analysis adopting polytropic Equations of State with the polytropic indices n=1, 3/2, and 5/2 and with two types of angular velocity profiles (the so-called j-constant-like and Kepler-like laws). It is confirmed that rotating stars of a high degree of differential rotation are dynamically unstable against the bar-mode deformation, even for the ratio of the kinetic energy to the gravitational potential energy $\beta$ of order 0.01. The criterion for onset of the bar-mode dynamical instability depends weakly on the polytropic index n and the angular velocity profile as long as the degree of differential rotation is high. Gravitational waves from the final nonaxisymmetric quasi-stationary States are calculated in the quadrupole formula. For proto-neutron stars of mass $1.4M_{\odot}$, radius $\sim 30$ km and $\beta \alt 0.1$, such gravitational waves have the frequency of $\sim$ 600--1,400 Hz, and the effective amplitude is larger than $10^{-22}$ at a distance of about 100 Mpc irrespective of n and the angular velocity profile.
Robert E Rutledge - One of the best experts on this subject based on the ideXlab platform.
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rejecting proposed dense matter Equations of State with quiescent low mass x ray binaries
The Astrophysical Journal, 2014Co-Authors: Sebastien Guillot, Robert E RutledgeAbstract:Neutrons stars are unique laboratories for discriminating between the various proposed Equations of State of matter at and above nuclear density. One sub-class of neutron stars—those inside quiescent low-mass X-ray binaries (qLMXBs)—produce a thermal surface emission from which the neutron star radius (R NS) can be measured, using the widely accepted observational scenario for qLMXBs, assuming unmagnetized H atmospheres. In a combined spectral analysis, this work first reproduces a previously published measurement of the R NS, assumed to be the same for all neutron stars, using a slightly expanded data set. The radius measured is . On the basis of spectral analysis alone, this measured value is not affected by imposing an assumption of causality in the core. However, the assumptions underlying this R NS measurement would be falsified by the observation of any neutron star with a mass >2.6 M ☉, since radii would be rejected if causality is assumed, which would exclude most of the R NS parameter space obtained in this analysis. Finally, this work directly tests a selection of dense matter Equations of State: WFF1, AP4, MPA1, PAL1, MS0, and three versions of Equations of State produced through chiral effective theory. Two of those, MS0 and PAL1, are rejected at the 99% confidence level, accounting for all quantifiable uncertainties, while the other cannot be excluded at >99% certainty.
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rejecting proposed dense matter Equations of State with quiescent low mass x ray binaries
arXiv: High Energy Astrophysical Phenomena, 2014Co-Authors: Sebastien Guillot, Robert E RutledgeAbstract:Neutrons stars are unique laboratories to discriminate between the various proposed Equations of State of matter at and above nuclear density. One sub-class of neutron stars - those inside quiescent low-mass X-ray binaries (qLMXBs) - produce a thermal surface emission from which the neutron star radius (R_NS) can be measured, using the widely accepted observational scenario for qLMXBs, assuming unmagnetized H atmospheres. In a combined spectral analysis, this work first reproduces a previously published measurement of the \rns, assumed to be the same for all neutron stars, using a slightly expanded data set. The radius measured is R_NS = 9.4 +/-1.2 km. On the basis of spectral analysis alone, this measured value is not affected by imposing an assumption of causality in the core. However, the assumptions underlying this R_NS measurement would be falsified by the observation of any neutron star with a mass >2.6 Msun, since radii 99% certainty.
J Read - One of the best experts on this subject based on the ideXlab platform.
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tidal deformability of neutron stars with realistic Equations of State and their gravitational wave signatures in binary inspiral
Physical Review D, 2010Co-Authors: Tanja Hinderer, B D Lackey, R N Lang, J ReadAbstract:The early part of the gravitational wave signal of binary neutron-star inspirals can potentially yield robust information on the nuclear equation of State. The influence of a star's internal structure on the waveform is characterized by a single parameter: the tidal deformability $\ensuremath{\lambda}$, which measures the star's quadrupole deformation in response to the companion's perturbing tidal field. We calculate $\ensuremath{\lambda}$ for a wide range of Equations of State and find that the value of $\ensuremath{\lambda}$ spans an order of magnitude for the range of equation of State models considered. An analysis of the feasibility of discriminating between neutron-star Equations of State with gravitational wave observations of the early part of the inspiral reveals that the measurement error in $\ensuremath{\lambda}$ increases steeply with the total mass of the binary. Comparing the errors with the expected range of $\ensuremath{\lambda}$, we find that Advanced LIGO observations of binaries at a distance of 100 Mpc will probe only unusually stiff Equations of State, while the proposed Einstein Telescope is likely to see a clean tidal signature.
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tidal deformability of neutron stars with realistic Equations of State and their gravitational wave signatures in binary inspiral
APS, 2010Co-Authors: Tanja Hinderer, B D Lackey, R N Lang, J ReadAbstract:The early part of the gravitational wave signal of binary neutron-star inspirals can potentially yield robust information on the nuclear equation of State. The influence of a star’s internal structure on the waveform is characterized by a single parameter: the tidal deformability λ, which measures the star’s quadrupole deformation in response to the companion’s perturbing tidal field. We calculate λ for a wide range of Equations of State and find that the value of λ spans an order of magnitude for the range of equation of State models considered. An analysis of the feasibility of discriminating between neutron-star Equations of State with gravitational wave observations of the early part of the inspiral reveals that the measurement error in λ increases steeply with the total mass of the binary. Comparing the errors with the expected range of λ, we find that Advanced LIGO observations of binaries at a distance of 100 Mpc will probe only unusually stiff Equations of State, while the proposed Einstein Telescope is likely to see a clean tidal signature.
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tidal deformability of neutron stars with realistic Equations of State and their gravitational wave signatures in binary inspiral
APS, 2010Co-Authors: Tanja Hinderer, B D Lackey, R N Lang, J ReadAbstract:The early part of the gravitational wave signal of binary neutron-star inspirals can potentially yield robust information on the nuclear equation of State. The influence of a star’s internal structure on the waveform is characterized by a single parameter: the tidal deformability λ, which measures the star’s quadrupole deformation in response to the companion’s perturbing tidal field. We calculate λ for a wide range of Equations of State and find that the value of λ spans an order of magnitude for the range of equation of State models considered. An analysis of the feasibility of discriminating between neutron-star Equations of State with gravitational wave observations of the early part of the inspiral reveals that the measurement error in λ increases steeply with the total mass of the binary. Comparing the errors with the expected range of λ, we find that Advanced LIGO observations of binaries at a distance of 100 Mpc will probe only unusually stiff Equations of State, while the proposed Einstein Telescope is likely to see a clean tidal signature.
R N Lang - One of the best experts on this subject based on the ideXlab platform.
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tidal deformability of neutron stars with realistic Equations of State and their gravitational wave signatures in binary inspiral
Physical Review D, 2010Co-Authors: Tanja Hinderer, B D Lackey, R N Lang, J ReadAbstract:The early part of the gravitational wave signal of binary neutron-star inspirals can potentially yield robust information on the nuclear equation of State. The influence of a star's internal structure on the waveform is characterized by a single parameter: the tidal deformability $\ensuremath{\lambda}$, which measures the star's quadrupole deformation in response to the companion's perturbing tidal field. We calculate $\ensuremath{\lambda}$ for a wide range of Equations of State and find that the value of $\ensuremath{\lambda}$ spans an order of magnitude for the range of equation of State models considered. An analysis of the feasibility of discriminating between neutron-star Equations of State with gravitational wave observations of the early part of the inspiral reveals that the measurement error in $\ensuremath{\lambda}$ increases steeply with the total mass of the binary. Comparing the errors with the expected range of $\ensuremath{\lambda}$, we find that Advanced LIGO observations of binaries at a distance of 100 Mpc will probe only unusually stiff Equations of State, while the proposed Einstein Telescope is likely to see a clean tidal signature.
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tidal deformability of neutron stars with realistic Equations of State and their gravitational wave signatures in binary inspiral
APS, 2010Co-Authors: Tanja Hinderer, B D Lackey, R N Lang, J ReadAbstract:The early part of the gravitational wave signal of binary neutron-star inspirals can potentially yield robust information on the nuclear equation of State. The influence of a star’s internal structure on the waveform is characterized by a single parameter: the tidal deformability λ, which measures the star’s quadrupole deformation in response to the companion’s perturbing tidal field. We calculate λ for a wide range of Equations of State and find that the value of λ spans an order of magnitude for the range of equation of State models considered. An analysis of the feasibility of discriminating between neutron-star Equations of State with gravitational wave observations of the early part of the inspiral reveals that the measurement error in λ increases steeply with the total mass of the binary. Comparing the errors with the expected range of λ, we find that Advanced LIGO observations of binaries at a distance of 100 Mpc will probe only unusually stiff Equations of State, while the proposed Einstein Telescope is likely to see a clean tidal signature.
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tidal deformability of neutron stars with realistic Equations of State and their gravitational wave signatures in binary inspiral
APS, 2010Co-Authors: Tanja Hinderer, B D Lackey, R N Lang, J ReadAbstract:The early part of the gravitational wave signal of binary neutron-star inspirals can potentially yield robust information on the nuclear equation of State. The influence of a star’s internal structure on the waveform is characterized by a single parameter: the tidal deformability λ, which measures the star’s quadrupole deformation in response to the companion’s perturbing tidal field. We calculate λ for a wide range of Equations of State and find that the value of λ spans an order of magnitude for the range of equation of State models considered. An analysis of the feasibility of discriminating between neutron-star Equations of State with gravitational wave observations of the early part of the inspiral reveals that the measurement error in λ increases steeply with the total mass of the binary. Comparing the errors with the expected range of λ, we find that Advanced LIGO observations of binaries at a distance of 100 Mpc will probe only unusually stiff Equations of State, while the proposed Einstein Telescope is likely to see a clean tidal signature.
