Determination of the Concentration of Gases by Measurement of Pressure

For the determination of the concentration of gases by means of pressure measurement, a precise equation of state is given by which analysis can be carried out within an accuracy of 10 ppm. The parameters of the equation of state are explicitely reported for carbon dioxide, argon, and helium

Synthetic magnetism for photon fluids

We develop a theory of artificial gauge fields in photon fluids for the cases of both second-order and third-order optical nonlinearities. This applies to weak excitations in the presence of pump fields carrying orbital angular momentum, and is thus a type of Bogoliubov theory. The resulting artificial gauge fields experienced by the weak excitations are an interesting generalization of previous cases and reflect the PT-symmetry properties of the underlying non-Hermitian Hamiltonian. We illustrate the observable consequences of the resulting synthetic magnetic fields for examples involving both second-order and third-order nonlinearities

Measurement and modelling of mass diffusion coefficients for application in carbon dioxide storage and enhanced oil recovery

In this work, measurements were carried out by the Taylor dispersion method [1, 2] to determine the mutual diffusion coefficient for CO2 in water or hydrocarbon at effectively infinite dilution. Measurements were carried out for CO2 in water, hexane, heptane, octane, decane, dodecane, hexadecane, cyclohexane, squalane and toluene at temperatures between 298 K and 423 K with pressures up to 69 MPa. Measurements of CO2 diffusivity in different brines were also carried out by 13C pulsed-field gradient NMR

Thermal diffusion segregation in granular binary mixtures described by the Enskog equation

Diffusion induced by a thermal gradient in a granular binary mixture is analyzed in the context of the (inelastic) Enskog equation. Although the Enskog equation neglects velocity correlations among particles which are about to collide, it retains spatial correlations arising from volume exclusion effects and thus it is expected to apply to moderate densities. In the steady state with gradients only along a given direction, a segregation criterion is obtained from the thermal diffusion factor $\Lambda$ measuring the amount of segregation parallel to the thermal gradient. As expected, the sign of the factor $\Lambda$ provides a criterion for the transition between the Brazil-nut effect (BNE) and the reverse Brazil-nut effect (RBNE) by varying the parameters of the mixture (masses, sizes, concentration, solid volume fraction, and coefficients of restitution). The form of the phase diagrams for the BNE/RBNE transition is illustrated in detail for several systems, with special emphasis on the significant role played by the inelasticity of collisions. In particular, an effect already found in dilute gases (segregation in a binary mixture of identical masses and sizes {\em but} different coefficients of restitution) is extended to dense systems. A comparison with recent computer simulation results shows a good qualitative agreement at the level of the thermal diffusion factor. The present analysis generalizes to arbitrary concentration previous theoretical results derived in the tracer limit case.Comment: 7 figures, 1 table. To appear in New J. Phys., special issue on "Granular Segregation