Abstract: Polycrystalline alumina and methods for manufacturing polycrystalline alumina exhibiting improved transmission in the infrared region. In one embodiment, the percent real in-line transmittance is within about 2% of sapphire at selected wavelengths. In one or more embodiments, polycrystalline articles exhibit improved mechanical properties such as thermal shock resistance and hardness, which may find use in armor applications.

Abstract: A pulse combustion device has a number of combustors with upstream bodies and downstream nozzles. Coupling conduits provide communication between the combustors. For each given combustor this includes a first communication between a first location upstream of the nozzle thereof and a first location along the nozzle of another. There is second communication between a second location upstream of the nozzle and a second communication between a second location upstream of the nozzle of a second other combustor and a second nozzle location along the nozzle of the given combustor.