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.

Microwave power engineering

Abstract: Microwaves for power (rather than communications) is today beyond a state of mere speculation. Interest in powering a hovering vehicle from the ground, power transmission via waveguides, and industrial potentialities have spurred the development of a technology that has already transmitted and utilized power efficiently

Method of Treating Zeeman Splittings of Paramagnetic Ions in Crystalline Fields

Abstract: In this paper, we present an alternative method to the "spin Hamiltonian" for treating the behavior of a paramagnetic ion under the combined influence of the host crystal and an applied magnetic field. This method has the advantage of being applicable to all strengths of couplings between the paramagnetic ion and the surrounding crystal. It is applicable to free-ion $S$ states in the same way that it applies to all other states. It gives all of the constants one needs to describe the energy level structure as a function of field as restricted by symmetry and the properties of the levels considered. The method is more general and is expected to be also more accurate than the conventional spin Hamiltonian formalism. It is illustrated by the application to the problem of the $({d}^{5})^{6}S$ level in a cubic crystalline environment.

The Star Formation Histories of Local Group Dwarf Galaxies. II. Searching For Signatures of Reionization

Abstract: We search for signatures of reionization in the star formation histories (SFHs) of 38 Local Group dwarf galaxies (10{sup 4} < M{sub *} < 10{sup 9} M{sub ☉}). The SFHs are derived from color-magnitude diagrams using archival Hubble Space Telescope/Wide Field Planetary Camera 2 imaging. Only five quenched galaxies (And V, And VI, And XIII, Leo IV, and Hercules) are consistent with forming the bulk of their stars before reionization, when full uncertainties are considered. Observations of 13 of the predicted 'true fossils' identified by Bovill and Ricotti show that only two (Hercules and Leo IV) indicate star formation quenched by reionization. However, both are within the virial radius of the Milky Way and evidence of tidal disturbance complicates this interpretation. We argue that the late-time gas capture scenario posited by Ricotti for the low mass, gas-rich, and star-forming fossil candidate Leo T is observationally indistinguishable from simple gas retention. Given the ambiguity between environmental effects and reionization, the best reionization fossil candidates are quenched low mass field galaxies (e.g., KKR 25).

Heat shield panels for use in a combustor for a gas turbine engine

Abstract: The present invention relates to heat shield panels or liners to be used in combustors for gas turbine engines. The heat shield panels each comprise a hot side and a cold side and at least one isolated cooling chamber on the cold side. Each cooling chamber has a plurality of cooling film holes for allowing a coolant, such as air, to flow from the cold side to the hot side. A combustor having an arrangement of heat shield panels or liners is also described.

A Tentative Detection of the Cosmic Infrared Background at 3.5 microns Using COBE/DIRBE Observations

Abstract: Foreground emission and scattered light from interplanetary dust (IPD) particles and emission from Galactic stellar sources are the greatest obstacles for determining the cosmic infrared background (CIB) from diffuse sky measurements in the ~ 1 to 5 micron range. We describe a new method for deriving the CIB at near infrared wavelengths which reduces the uncertainties associated with the removal of the Galactic stellar emission component from the sky maps. The method produces positive residuals at 3.5 and 4.9 microns, of which only the 3.5 micron residual is nearly isotropic. We consider our result as a tentative detection of the CIB at this wavelength.