27 research outputs found
Permeability and conductivity of platelet-reinforced membranes and composites
We present large scale simulations of the diffusion constant of a random
composite consisting of aligned platelets with aspect ratio in a
matrix (with diffusion constant ) and find that , where and is the platelet volume fraction. We
demonstrate that for large aspect ratio platelets the pair term ()
dominates suggesting large property enhancements for these materials. However a
small amount of face-to-face ordering of the platelets markedly degrades the
efficiency of platelet reinforcement.Comment: RevTeX, 5 pages, 4 figures, submitted to PR
A compact quantum-cascade laser based spectrometer for monitoring the concentrations of methane and nitrous oxide in the troposphere
A spectrometer, based on the frequency down-chirped radiation from a pulsed quantum-cascade laser, capable of detecting fluctuations in local ground level methane and nitrous oxide concentrations over a time scale of minutes, is presented. The applicability of this instrument to low-level atmospheric detection is demonstrated through sampling gases in two locations