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.

Leo p: an unquenched very low-mass galaxy*

Abstract: Leo P is a low-luminosity dwarf galaxy discovered through the blind HI Arecibo Legacy Fast ALFA (ALFALFA) survey. The HI and follow-up optical observations have shown that Leo P is a gas-rich dwarf galaxy with active star formation, an underlying older population, and an extremely low oxygen abundance. We have obtained optical imaging with the Hubble Space Telescope to two magnitudes below the red clump in order to study the evolution of Leo P. We refine the distance measurement to Leo P to be 1.62+/-0.15 Mpc, based on the luminosity of the horizontal branch stars and 10 newly identified RR Lyrae candidates. This places the galaxy at the edge of the Local Group, ~0.4 Mpc from Sextans B, the nearest galaxy in the NGC 3109 association of dwarf galaxies of which Leo P is clearly a member. The star responsible for ionizing the HII region is most likely an O7V or O8V spectral type, with a stellar mass >25 Msun. The presence of this star provides observational evidence that massive stars at the upper-end of the initial mass function are capable of being formed at star formation rates as low as ~10^-5 Msun/yr. The best-fitting star formation history derived from the resolved stellar populations of Leo P using the latest PARSEC models shows a relatively constant star formation rate over the lifetime of the galaxy. The modeled luminosity characteristics of Leo P at early times are consistent with low-luminosity dSph Milky Way satellites, suggesting that Leo P is what a low-mass dSph would look like if it evolved in isolation and retained its gas. Despite the very low mass of Leo P, the imprint of reionization on its star formation history is subtle at best, and consistent with being totally negligible. The isolation of Leo P, and the total quenching of star formation of Milky Way satellites of similar mass, implies that local environment dominates the quenching of the Milky Way satellites.

The technology and application of free-space power transmission by microwave beam

Abstract: The point-to-point transfer of power by a microwave beam is an emerging technology with several unique characteristics and applications. The technology is examined in terms of the microwave beam itself, and the conversion technology between microwaves and dc power at either end of the system. The existing efficiencies and the projected efficiencies for the overall system and its elements are emphasized. The procedure for designing a highly efficient microwave beam power transfer system of arbitrary length starting from the microwave generator and terminating with the receiving aperture is given. The potential applications are discussed in terms of the unique characteristics of microwave power transmission. The successful experimental work on microwave-powered helicopters is reviewed. A potential application to bring down power from space is examined.

Assessing the impact of healthy work organization intervention

Abstract: This research evaluates a healthy work organization intervention implemented in a retail setting. Using a participatory process, employee teams in I I intervention stores developed customized plans for improving work organization at their sites. Ten comparable stores served as controls. Employee surveys were administered prior to the intervention and twice again at 12-month intervals. Business results were compiled monthly for each store. The baseline data were used by the teams to identify needs and establish action priorities for their stores. Most study outcomes declined across time for all stores, due primarily to internal corporate events and a generally adverse economic environment. However, the intervention process appeared to buffer some of these declines; intervention stores fared better in terms of selected aspects of organizational climate and psychological work adjustment. Intervention stores also performed better than controls on general indices of perceived health and safety and two of the four business outcomes: employee turnover and sales per labour hour. These results are discussed in terms of the challenges involved in evaluating organizational-level interventions in work settings.

Methods and apparatus for volumetric coverage with image beam super-elements

Abstract: Methods and apparatus for a super-element assembly for a phased array radar aperture, the super-element assembly having a first port and a second port to receive a first signal at the first port to generate a main beam, and receive a second signal at the second port to generate an image beam for generating scan volume coverage using the main and image beams.