pyrolysis of low density polyethylene (ldpe) by equilibrium fluid catalytic cracking (fcc) was studied in a stirred reactor under different process parameters. in this work, the effect of process parameters such as degradation temperature (420-510°c), catalyst/polymer ratio (0-60%), carrier gas type (h2, n2, ethylene, propylene, ar and he), residence time and agitator speed (0-300 rpm) on the c...

A grand canonical system of hard-core bosons in an optical lattice is considered. The bosons can occupy randomly N equivalent states at each lattice site. The limit N → ∞ is solved exactly in terms of a saddle-point integration, representing a weakly-interacting Bose gas. In the limit N → ∞ there is only a condensate if the fugacity of the Bose gas is larger than 1. Corrections in 1/N increase ...

Polarization-dependent phase-contrast imaging is used to resolve the spatial magnetization profile of an optically trapped ultracold gas. This probe is applied to Larmor precession of degenerate and nondegenerate spin-1 87Rb gases. Transverse magnetization of the Bose-Einstein condensate persists for the condensate lifetime, with a spatial response to magnetic field inhomogeneities consistent w...

Damping in a dilute Bose gas is investigated using a mean-field approximation which describes the coupled oscillations of condensate and non-condensate atoms in the collisionless regime. Explicit results for both Landau and Beliaev damping rates are given for non-uniform gases. In the case of uniform systems we obtain results for the damping of phonons both at zero and finite temperature. The i...

We show that in an atomic Bose gas near a Feshbach resonance a quantum phase transition occurs between a phase with only a molecular Bose-Einstein condensate and a phase with both an atomic and a molecular Bose-Einstein condensate. We show that the transition is characterized by an Ising order parameter. We also determine the phase diagram of the gas as a function of magnetic field and temperat...

We present a method of adiabatically changing the local phase-space density of an ultracold gas using a combination of magnetic and optical forces. Applying this method, we observe phase-space density increases in a gas of sodium atoms by as much as 50-fold. The transition to Bose-Einstein condensation was crossed reversibly, attaining condensate fractions of up to 30%. Measurements of the cond...