  Quasi-2D bidisperse amorphous systems of steel beads are fluidized by a
uniform upflow of air, so that the beads roll on a horizontal plane. The
short-time ballistic motion of the beads is stochastic, with non-Gaussian speed
distributions and with different average kinetic energies for the two species.
The approach to jamming is studied as a function of increasing bead area
fraction and also as a function of decreasing air speed. The structure of the
system is measured in terms of both the Voronoi tessellation and the pair
distribution function. The dynamics of the system is measured in terms of both
displacement statistics and the density of vibrational states. These quantities
all exhibit tell-tale features as the dynamics become more constrained closer
to jamming. Though the system is driven and athermal, the behavior is
remarkably reminiscent of that in dense colloidal suspensions and supercooled
liquids.
