Raytheon

About: Raytheon is a company organization based out in Waltham, Massachusetts, United States. It is known for research contribution in the topics: Signal & Antenna (radio). The organization has 15290 authors who have published 18973 publications receiving 300052 citations.

Multiple adaptive filter active noise canceller

Abstract: An active adaptive noise canceller (100) that does not require a training mode and operates over an extended noise bandwidth. The canceller partitions the noise bandwidth into frequency sub-bands, and multiple adaptive filter channels (120, 140) are employed, one for each sub-band, to cancel noise energy in the respective sub-bands. Each channel includes bandpass filters (121, 130) to restrict the channel to operation over only the particular sub-band, and delays are inserted in the operation of the filter weight updating. Because each channel is stable over its sub-band, the canceller operates over the extended noise bandwidth of all the sub-bands.

Blade outer air seal

Abstract: A turbine engine blade outer air seal segment has a body having a base portion. The base portion has a transversely concave ID face, a forward end, an aft end, and first and second circumferential edges. The body has at least one mounting hook. At least one cover plate is secured to the body to define at least one cavity. The cover plate has a plurality of feed holes. A plurality of outlet holes extend through the base portion to the ID face. At least one of the base portion and cover plate comprises a protruding portion protruding into the cavity to form a partial restriction separating circumferentially and fore-aft offset cavity portions.

Experiments in the transportation of energy by microwave beam

Abstract: The recent development of efficient microwave tubes generating hundreds of kilowatts of continuous power at a wavelength of 10 cm has motivated the first initial experiment in utilizing a microwave beam as a means of transporting energy from one point to another. The experiment made use of a CW magnetron operating at 2450 Mc with several hundred watts of power output for the power source, a 9.5 foot diameter ellipsoidal transmitting antenna, a diagonal-horn receiving antenna separated from the transmitting antenna by 25 feet, and a close-spaced thermionic diode rectifier. The overall efficiency as measured from the output of the microwave generator to the input of an electric motor attached to the output of the microwave rectifier at the receiving point was 26%. Although this experiment handled a modest amount of power over a short distance, sufficient "on-the-shelf" technology now exists in each of the component areas to increase the power-handling capability and the distance over which power can be transferred by at least a thousandfold.

Phonon scattering in strained transition layers for GaN heteroepitaxy

Abstract: Strained transition layers, which are common for heteroepitaxial growth of functional semiconductors on foreign substrates, include high defect densities that impair heat conduction. Here, we measure the thermal resistances of AlN transition layers for GaN on Si and SiC substrates in the temperature range $300lTl550$ K using time-domain thermoreflectance. We propose a model for the effective resistance of such transition films, which accounts for the coupled effects of phonon scattering on defects and the two interfaces. The data are consistent with this model using point defects at concentrations near 10${}^{20}$ cm${}^{\ensuremath{-}3}$ and transmission coefficients based on the diffuse mismatch model. The data can be also described using lower transmission coefficients and eliminating the defects in the AlN. The data and modeling support the hypothesis that point defect scattering in the AlN film dominates the resistance, but may also be consistent with a high presence of near-interfacial defects in the bounding films.