Towards frustration of freezing transition in a binary hard-disk mixture

The freezing mechanism, recently suggested for a monodisperse hard-disk fluid [Huerta et al., Phys. Rev. E, 2006, 74, 061106] is extended here to an equimolar binary hard-disk mixtures. We are showing that for diameter ratios, smaller than 1.15 the global orientational order parameter of the binary mixture behaves like in the case of a monodisperse fluid. Namely, by increasing the disk number density there is a tendency to form a crystalline-like phase. However, for diameter ratios larger than 1.15 the binary mixtures behave like a disordered fluid. We use some of the structural and thermodynamic properties to compare and discuss the behavior as a function of diameter ratio and packing fraction.Comment: 9 pages, 4 figure

Sea Contributions to Spin 1/2 Baryon Structure, Magnetic Moments, and Spin Distribution

We treat the baryon as a composite system made out of a \lq\lq core" of three quarks (as in the standard quark model) surrounded by a \lq\lq sea" (of gluons and $q\bar{q}$-pairs) which is specified by its total quantum numbers like flavor, spin and color. Specifically, we assume the sea to be a flavor octet with spin 0 or 1 but no color. The general wavefunction for spin 1/2 baryons with such a sea component is given. Application to the magnetic moments is considered. Numerical analysis shows that a scalar (spin 0) sea with an admixture of a vector (spin 1) sea can provide very good fits to the magnetic moment data {\em using experimental errors}. Our best fit automatically gives $g_A/g_V$ for neutron beta decay in agreement with data. This fit also gives reasonable values for the spin distributions of the proton and neutron.Comment: 24 pages, REVTEX. References modifie

Deim-based pgd for multi-parametric nonlinear model reduction

A new technique for efficiently solving parametric nonlinear reduced order models in the Proper Generalized Decomposition (PGD) framework is presented here. This technique is based on the Discrete Empirical Interpolation Method (DEIM)[1], and thus the nonlinear term is interpolated using the reduced basis instead of being fully evaluated. The DEIM has already been demonstrated to provide satisfactory results in terms of computational complexity decrease when combined with the Proper Orthogonal Decomposition (POD). However, in the POD case the reduced basis is a posteriori known as it comes from several pre-computed snapshots. On the contrary, the PGD is an a priori model reduction method. This makes the DEIM-PGD coupling rather delicate, because different choices are possible as it is analyzed in this work

Analytical solutions for the isobaric evaporation of pure cryogens in storage tanks

New analytical solutions have been derived for the isobaric evaporation of a pure liquid cryogen. In particular, expressions have been provided for the liquid volume, evaporation rate, Boil-off-Gas (BOG) rate, vapour temperature and vapour to liquid heat transfer rate as a function of time. Both equilibrium and non-equilibrium scenarios have been considered. In the former, the vapour and liquid cryogen are assumed to be in thermal equilibrium, while in the latter the vapour is treated as superheated with respect to the liquid and acts as an additional heat source. The derived solutions for two scenarios were validated against the numerical results for the evaporation of liquid methane and of liquid nitrogen in small, medium sized and large storage tanks that are used in industry. For the equilibrium model, the analytical solutions are exact. For the non-equilibrium model, the analytical solutions are valid for the whole duration of evaporation, except for a short transient period at the beginning of the evaporation. For physical quantities of industrial interest, they provide accurate estimates of liquid volume, BOG rate and BOG temperature, with the maximum deviations not exceeding 1%, 2% and 4.5%, respectively. The vapour to liquid heat transfer rate is also well predicted to within a maximum deviation of 5%

Predicting the viscosity of liquid mixtures consisting of n-alkane, alkylbenzene and cycloalkane species based on molecular description

1-component Extended Hard-Sphere (1-cEHS) model has been developed recently to predict the viscosity of liquid, n-alkane mixtures. It represents a mixture by a single pseudo-component characterized by an appropriate molecular weight and calculates the viscosity by means of the modified, extended hard-sphere model (EHS) that makes use of a universal function relating reduced viscosity to reduced volume. In this work we have extended the model to also predict the viscosity of mixtures containing alkylbenzene and cycloalkane species. Furthermore, we have developed a new 3-component Extended Hard-Sphere (3-cEHS) model which requires only a knowledge of the overall composition of n-alkane, alkylbenzene and cycloalkane species. Extensive comparison with the available experimental data indicates that both models (1-cEHS and 3-cEHS) predict the viscosity of binary and multicomponent mixtures containing n-alkane, alkylbenzene and cycloalkane species with uncertainty of 5–10%. The proposed models are a precursor of a new family of models that do not require a knowledge of the detailed composition of the mixture, but still take advantage of the underlying molecular description