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71.
Lin Zhang Ying-Hua LiYu-Ying Yu Xue-Mei LiYun Ma Cheng-Gang GuCheng-Da Dai Ling-Cang Cai 《Physica B: Condensed Matter》2011,406(22):4163-4169
The mean-field potential (MFP) approach is an efficient way to evaluate the free energy contribution of ion motions for both solid and liquid states. In this paper the MFP is generally constructed with a volume-dependent term and a shape function. The former is derived in accordance with quasi-harmonic approximation. The latter is given semi-empirically. Application to multiphase equations of state for β-, γ- and liquid-tin has been examined. The theoretical phase diagram and thermodynamic properties of isotherm, thermal expansion, heat capacity, Hugoniot states as well as phase transitions are all in excellent agreement with experiments. 相似文献
72.
We employ an isospin dependent version of the QMD transport model to study the influence of the isospin dependent part of the nuclear matter equation of state and in-medium nucleon–nucleon cross-sections on the dynamics of heavy-ion collisions at intermediate energies. We find that the extraction of useful information on the isospin-dependent part of the equation of state of nuclear matter from proton or neutron elliptic flows is obstructed by their sensitivity to model parameters and in-medium values of nucleon–nucleon cross-sections. Opposite to that, neutron–proton elliptic flow difference shows little dependence on those variables while its dependence on the isospin asymmetric EoS is enhanced, making it more suitable for a model independent constraining of the high-density behaviour of asy-EoS. Comparison with existing experimental FOPI-LAND neutron–hydrogen data can be used to set an upper limit to the softness of asy-EoS. Successful constraining of the asy-EoS via neutron–proton elliptic flow difference will require experimental data of higher accuracy than presently available. 相似文献
73.
We calculate the strange star properties in the framework of the Field Correlator Method. We find that for gluon condensate values G2 in the range 0.006–0.007 GeV4, which give a critical temperature Tc∼170 MeV at μc=0, the sequences of strange stars are compatible with some of the semi-empirical mass–radius relations and data obtained from astrophysical observations. 相似文献
74.
A lower triangular matrix with nonzero principal diagonal entries is called a triangle. In this paper we obtain the sufficient conditions for ∑anλn to be summable ∣A∣k whenever ∑an is summable ∣T∣k for a triangle T. 相似文献
75.
Uri. Goldberg 《International Journal of Computational Fluid Dynamics》2013,27(1):27-38
A new topography-parameter-free turbulence closure, based on a transport equation for the pseudo eddy viscosity, is described. The model is tested against experimental data of several flow cases across the Mach number range and compared to Menter's single equation model and to the Spalart-Allmaras model. The main conclusion is that the new closure outperforms the other two models in both low and high speed flows. 相似文献
76.
Humberto Hinojosa-GómezAuthor Vitae J. Fernando Barragán-ArocheEnrique R. Bazúa-RuedaAuthor Vitae 《Fluid Phase Equilibria》2010
In this work we present two modifications to the Peng–Robinson-Fitted equation of state where pure component parameters are regressed to vapor pressure and saturated liquid density data. The first modification (PR-f-mod) is a method that enhances the equation of state pure component property predictions through simple temperature dependent pure component parameters. In the second modification (PR-f-prop) we propose a temperature dependency for co-volume b in the repulsive parameter of the EoS, and revise the temperature function in the attractive term. The agreement with experimental data for 72 pure substances, including highly polar compounds, is remarkably good. We obtain average absolute deviations in saturated liquid density of less than 1% for all substances studied. 相似文献
77.
Using a similar approach as Lencka and Anderko [AIChE J. 39 (1993) 533], we developed an equation of state for hydrogen fluoride (HF), which can correlate the vapor pressure, the saturated liquid and vapor densities of it from the triple point to critical point with good accuracy. We used an equilibrium model to account for hydrogen bonding that assumes the formation of dimer, hexamer, and octamer species as suggested by Schotte [Ind. Eng. Chem. Process Des. Dev. 19 (1980) 432]. The physical and chemical parameters are obtained directly from the regression of pure component properties by applying the critical constraints to the equation of state for hydrogen fluoride. This equation of state together with the Wong–Sandler mixing rule as well as the van der Waals one-fluid mixing rule are used to correlate the phase equilibria of binary hydrogen fluoride mixtures with HCl, HCFC-124, HFC-134a, HFC-152a, HCFC-22, and HFC-32. For these systems, new equation of state with the Wong–Sandler mixing rule gives good results. 相似文献
78.
It is emphasized that any equation of state (EOS) based on the generalized Lennard-Jones potential or the Mie potential, suffers
from two main shortcomings as pointed out by Stacey and Davis [2]. One of the shortcomings viz. the problem related to imaginary numbers for the exponents in the potential function, has been removed recently by Jiuxun
[11] by using a relationship between the exponents. However, the modified EOS obtained by Jiuxun suffers from the second shortcoming
viz. it gives lower values for −B
0
B″0, an important equation of state parameter related to the second pressure derivative of the bulk modulus. Values of B
0
B″0 obtained by Jiuxun are not consistent with those reported by Stacey and Davis.
相似文献
79.
We give a geometrical proof of a Muhometov type inequality, for a single Riemannian metric defined on a closed disc in the plane. We mainly study the case of equality which is achieved if and only if the distance between points on the boundary is invariant under rotation along the boundary. We show that this implies that the metric itself must be invariant under rotation, at least when the metric is analytic or of nonpositive curvature. 相似文献
80.
M.A.M. Alwash 《Journal of Mathematical Analysis and Applications》2007,329(2):1161-1169
For a class of polynomial non-autonomous differential equations of degree n, we use phase plane analysis to show that each equation in this class has n periodic solutions. The result implies that certain rigid two-dimensional systems have at most one limit cycle which appears through multiple Hopf bifurcation. 相似文献