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.

Bidirectional Reflectance Round-Robin in Support of the Earth Observing System Program

Abstract: Laboratory measurements of the bidirectional reflectance distribution function (BRDRF) of diffuse reflectors are required to support calibration in the Earth Observing System (EOS) program of the National Aeronautics and Space Administration.

N-BIT 2's COMPLEMENT SYMMETRIC ROUNDING METHOD AND LOGIC FOR IMPLEMENTING THE SAME

Abstract: A rounding circuit is provided that includes an input for receiving a 2's complement number to be rounded. The 2's complement number has a format SXY, where S represents a sign bit, X represents one or more bits to round and keep, and Y represents one or more bits to be discarded. The rounding circuit also includes first logic for adding a rounding bias to the 2's complement number, and second logic for at least one of subtracting the sign bit S from the 2's complement number, or adding the inverted sign bit !S to the 2's complement number. Moreover, the rounding circuit includes third logic for truncating Y bits from a result produced by the first and second logic to produce a rounded 2's complement number having a format SX.

Delving Deeper into the Tumultuous Lives of Galactic Dwarfs: Modeling Star Formation Histories

Abstract: The paucity of observed dwarf galaxies in the Local Group relative to the abundance of predicted dark matter halos remains one of the greatest puzzles of the LCDM paradigm. Solving this puzzle now requires not only matching the numbers of objects but also understanding the details of their star formation histories. We present a summary of such histories derived from the HST data using the color-magnitude diagram fitting method. To reduce observational uncertainties, we condense the data into five cumulative parameters -- the fractions of stellar mass formed in the last 1, 2, 5, and 10 Gyr, and the mean stellar age. We interpret the new data with a phenomenological model based on the mass assembly histories of dark matter halos and the Schmidt law of star formation. The model correctly predicts the radial distribution of the dwarfs and the fractions of stars formed in the last 5 and 10 Gyr. However, in order to be consistent with the observations, the model requires a significant amount of recent star formation in the last 2 Gyr. Within the framework of our model, this prolonged star formation can be achieved by adding a stochastic variation in the density threshold of the star formation law. The model results are not sensitive to late gas accretion, the slope of the Schmidt law, or the details of cosmic reionization. A few discrepancies still remain: our model typically predicts too large stellar masses, only a modest population of ultra-faint dwarfs, and a small number of dwarfs with anomalously young stellar populations. Nevertheless, the observed star formation histories of Local Group dwarfs are generally consistent the expected star formation in cold dark matter halos.

Teleoperated robotic system

Abstract: A teleoperated robotic system that includes master control arms, slave arms, and a mobile platform. In use, a user manipulates the master control arms to control movement of the slave arms. The teleoperated robotic system can include two master control arms and two slave arms. The master control arms and the slave arms can be mounted on the platform. The platform can provide support for the master control arms and for a teleoperator, or user, of the robotic system. Thus, a mobile platform can allow the robotic system to be moved from place to place to locate the slave arms in a position for use. Additionally, the user can be positioned on the platform, such that the user can see and hear, directly, the slave arms and the workspace in which the slave arms operate.

Heterodyne measurements of light propagation through atmospheric turbulence

Abstract: Experiments on the phase perturbation of optical beams due to atmospheric turbulence were carried out using coherent radiation at 6328 A, and 1.15 µ. The measurements were accomplished using a modulated interferometer to produce Doppler beats between a reference beam and one reflected from a plane mirror at a distance. This paper presents preliminary results of the phase measurements taken over total horizontal paths of 4.0 km and 23.8 km. The experimental data were consistent with a propagation theory based on the accepted model of atmospheric turbulence. Perturbation free apertures up to 10 cm were observed in good seeing conditions and as low as 1 mm under poor conditions. The corresponding variance of refractive index of the atmosphere showed a magnitude and diurnal variation consistent with published observations of temperature fluctuations.