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.

Search for gravitational waves from binary black hole inspirals in LIGO data

Abstract: We report on a search for gravitational waves from binary black hole inspirals in the data from the second science run of the LIGO interferometers. The search focused on binary systems with component masses between 3 and 20M⊙. Optimally oriented binaries with distances up to 1 Mpc could be detected with efficiency of at least 90%. We found no events that could be identified as gravitational waves in the 385.6 hours of data that we searched.

Evolution of thermally pulsing asymptotic giant branch stars. iv. constraining mass loss and lifetimes of low mass, low metallicity agb stars*

Abstract: The evolution and lifetimes of thermally pulsating asymptotic giant branch (TP-AGB) stars suffer from significant uncertainties. In this work, we analyze the numbers and luminosity functions of TP-AGB stars in six quiescent, low metallicity ([Fe/H] –0.86) galaxies taken from the ACS Nearby Galaxy Survey Treasury sample, using Hubble Space Telescope (HST) photometry in both optical and near-infrared filters. The galaxies contain over 1000 TP-AGB stars (at least 60 per field). We compare the observed TP-AGB luminosity functions and relative numbers of TP-AGB and red giant branch (RGB) stars, N TP-AGB/N RGB, to models generated from different suites of TP-AGB evolutionary tracks after adopting star formation histories derived from the HST deep optical observations. We test various mass-loss prescriptions that differ in their treatments of mass loss before the onset of dust-driven winds (pre-dust). These comparisons confirm that pre-dust mass loss is important, since models that neglect pre-dust mass loss fail to explain the observed N TP-AGB/N RGB ratio or the luminosity functions. In contrast, models with more efficient pre-dust mass loss produce results consistent with observations. We find that for [Fe/H] –0.86, lower mass TP-AGB stars (M 1 M ☉) must have lifetimes of ~0.5 Myr and higher masses (M 3 M ☉) must have lifetimes 1.2 Myr. In addition, assuming our best-fitting mass-loss prescription, we show that the third dredge-up has no significant effect on TP-AGB lifetimes in this mass and metallicity range.

Brightness control for flat panel display

Abstract: For controlling the brightness of a matrix-addressed flat panel CRT display (70) of a type having intersecting column and row conductors (72,74) forming, respectively, the cathode and gate electrodes of a field electron emission array (76), the brightness control effected by controlling both the duty cycle and the voltage applied to the drive lines of the intersecting conductors (72,74). A periodic staircase waveform having progressively increasing voltage steps (VROW) is sequentially applied to the row conductors (74). The voltages (VROW) at each of the steps are selected to enable electron beam currents which proved brightness levels which are twice the brightness of the previous step. Binary-coded video brightness data are simultaneously applied to all of the column conductors (72). The combined voltages at the intersections of the selected conductors cause a sequence of electron emissions onto luminescing means which result in a corresponding sequence of illumination intervals. The human optic system integrates this illumination sequence into the selected brightness level. In addition, the overall brightness of the display is controlled by gating (84) the waveforms for the column conductors (74) with a pulse train comprising a sequence of adjustable, uniform-width pulses from an adjusting one shot (88).

Systematic study of fields due to extended apertures by Gaussian beam discretization

Abstract: Gaussian beams are used as basis elements in field representations. To gain insight into how the choice of beam parameters affects the final representation, a systematic study for the simple test case of a one-dimensional linearly phased cosine-aperture distribution has been undertaken. By successively adding individual displaced and/or tilted beams with large, narrow, or matched waists, one can assess how the elements in various portions of the lattice contribute to the build-up of the actual field in the aperture, near zone, and far zone. Adding enough beams always guarantees homing in on the exact solution, as is verified here by independent comparison. Different beam choices imply different modeling of the radiation process. The understanding gained thereby is helpful for selecting beam parameters in subsequent applications where it is necessary to balance requirements of good convergence, ease of computation, and ability to track the beams through perturbing environments like a radome. Indications are that the narrow beams provide the most robust and versatile formulation to deal with these generalized conditions. >

Networked symbiotic edge user infrastructure

Abstract: A networked symbiotic assistive user system is presented. The architecture of the system allows devices worn by medical first responders such as medics or EMTs, to connect wirelessly to devices coupled to patients, devices worn by other medical first responders and adapter devices (such as those that may be located in air and/or land evacuation vehicles) that connect to a legacy infrastructure. Using a variety of medical first responder oriented communications protocols and applications, the devices can exchange information with all of the other devices in a manner that assists the medical first responders as well as personnel associated with the legacy infrastructure (e.g., tactical command operations personnel, first aid station personnel, or other medical facilities personnel).