52 research outputs found
Gauge-ready formulation of the cosmological kinetic theory in generalized gravity theories
We present cosmological perturbations of kinetic components based on
relativistic Boltzmann equations in the context of generalized gravity
theories. Our general theory considers an arbitrary number of scalar fields
generally coupled with the gravity, an arbitrary number of mutually interacting
hydrodynamic fluids, and components described by the relativistic Boltzmann
equations like massive/massless collisionless particles and the photon with the
accompanying polarizations. We also include direct interactions among fluids
and fields. The background FLRW model includes the general spatial curvature
and the cosmological constant. We consider three different types of
perturbations, and all the scalar-type perturbation equations are arranged in a
gauge-ready form so that one can implement easily the convenient gauge
conditions depending on the situation. In the numerical calculation of the
Boltzmann equations we have implemented four different gauge conditions in a
gauge-ready manner where two of them are new. By comparing solutions solved
separately in different gauge conditions we can naturally check the numerical
accuracy.Comment: 26 pages, 9 figures, revised thoroughly, to appear in Phys. Rev.
Modeling of droplet generation in a top blowing steelmaking process
Quantification of metal droplets ejected due to impinging gas jet on the surface of liquid metal is an important parameter for the understanding and for the modeling of the refining kinetics of reactions in slag-metal emulsion zone. In the present work, a numerical study has been carried out to critically examine the applicability of droplet generation rate correlation previously proposed by Subagyo et al. on the basis of dimensionless blowing number (N B). The blowing number was re-evaluated at the impingement point of jet with taking into account the temperature effect of change in density and velocity of the gas jet. The result obtained from the work shows that the modified blowing number N B,T at the furnace temperature of 1873 K (1600 °C) is approximately double in magnitude compared to N B calculated by Subagyo and co-workers. When N B,T has been employed to the Subagyo’s empirical correlation for droplet generation, a wide mismatch is observed between the experimental data obtained from cold model and hot model experiments. The reason for this large deviation has been investigated in the current study, and a theoretical approach to estimate the droplet generation rate has been proposed. The suitability of the proposed model has been tested by numerically calculating the amount of metals in slag. The study shows that the weight of metals in emulsion falls in the range of 0 to 21 wt pct of hot metal weight when droplet generation rate has been calculated at ambient furnace temperature of 1873 K (1600 °C)
Solvable model of dissipative dynamics in the deep strong coupling regime
We describe the dynamics of a qubit interacting with a bosonic mode coupled
to a zero-temperature bath in the deep strong coupling (DSC) regime. We provide
an analytical solution for this open system dynamics in the off-resonance case
of the qubit-mode interaction. Collapses and revivals of parity chain
populations and the oscillatory behavior of the mean photon number are
predicted. At the same time, photon number wave packets, propagating back and
forth along parity chains, become incoherently mixed. Finally, we investigate
numerically the effect of detuning on the validity of the analytical solution.Comment: 6 pages, 8 figure
MR regional perfusion imaging: Visualizing functional collateral circulation
American Journal of Neuroradiology283447-44
Annual Research Review: Growth connectomics – the organization and reorganization of brain networks during normal and abnormal development
Deep Vein Thrombosis and Changes in Coagulation and Fibrinolysis after Gynaecological Operations in Chinese: the Effect of Oral Contraceptives and Malignant Disease
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