Experiments were performed in a three-phase bubble column to study variations of bubble rise velocities. The dynamic gas disengagement (DGD) technique and the fast response pressure transducers were utilized to investigate the bubble rise in the column. The superficial gas velocity of large bubbles and small bubbles, the rise velocities of larger and small bubble fractions were studied consider...

The law of conservation of linear momentum is applied to surface gas exchanges, employing scale analysis to diagnose the vertical velocity (w) in the boundary layer. Net upward momentum in the surface layer is forced by evaporation (E) and defines non-zero vertical motion, with a magnitude defined by the ratio of E to the air density, as w = E ρ . This is true even right down at the surface whe...

We investigate the evolution of the velocity distribution function of a granular gas composed of viscoelastic particles in the homogeneous cooling state, i.e. before clustering occurs. The deviation of the velocity distribution function from the Maxwellian distribution is quantified by a Sonine polynomials expansion. The first non-vanishing Sonine coefficient a2(t), reveals a complex time depen...

We demonstrate in this paper that the velocity widths of the neutral gas in Damped Lyα (DLA) systems are inconsistent with these systems originating in gas disks of galaxies similar to those seen in the local universe. We examine the gas kinematics of local galaxies using the high quality H I 21-cm data from the H I Nearby Galaxies Survey (THINGS) and make a comparison with the velocity profile...

Vacuum physics is the necessary condition for scientific research and modern high technology. In this introduction to the physics and technology of vacuum the basic concepts of a gas composed of atoms and molecules are presented. These gas particles are contained in a partially empty volume forming the vacuum. The fundamentals of vacuum, molecular density, pressure, velocity distribution, mean ...

in this research, process asymmetric polyetherimide hollow fiber membranes using ethanol (0, 2 and 4 wt%) as non-solvent additive in the polymer dope via phase inversion method were fabricated. aqueous solution of 1-methyl-2-pyrrolidine (nmp) (90%) was applied as a bore fluid to avoid inner skin layer formation and water was used as the external coagulant. the morphology of fabricated membranes...

We study the two dimensional XY model with quenched random phases and its Coulomb gas formulation. A novel renormalization group (RG) method is developed which allows to study perturbatively the glassy low temperature XY phase and the transition at which frozen topological defects (vortices) proliferate. This RG approach is constructed both from the replicated Coulomb gas and, equivalently with...

We present the results of high velocity (1.3 km s channels) and high spatial (∼5, or ∼ 250 pc at the distance of I Zw 18) resolution HI synthesis observations of the blue compact dwarf galaxy I Zw 18 to investigate the link between its unique evolutionary history and the neutral gas distribution and kinematics. The HI distribution is extensive, with diffuse neutral gas extending to the northwes...

We present the results of high velocity (1.3 km s channels) and high spatial (∼5, or ∼ 250 pc at the distance of I Zw 18) resolution HI synthesis observations of the blue compact dwarf galaxy I Zw 18 to investigate the link between its unique evolutionary history and the neutral gas distribution and kinematics. The HI distribution is extensive, with diffuse neutral gas extending to the northwes...

Models were developed for prediction and interpretation of the observed steady-state axial dissolved oxygen concentration profiles in tall airlift bioreactors. The observed concentration profiles were non-linear because of a combination of hydrodynamic and mass transport factors. The profiles were influenced mainly by the liquid-phase axial dispersion coefficient, the volumetric overall gas–liq...