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.

Nonlinear filters with log-homotopy

Abstract: We derive and test a new nonlinear filter that implements Bayes' rule using an ODE rather than with a pointwise multiplication of two functions. This avoids one of the fundamental and well known problems in particle filters, namely "particle collapse" as a result of Bayes' rule. We use a log-homotopy to construct this ODE. Our new algorithm is vastly superior to the classic particle filter, and we do not use any proposal density supplied by an EKF or UKF or other outside source. This paper was written for normal engineers, who do not have homotopy for breakfast.

The star formation histories of local group dwarf galaxies. iii. characterizing quenching in low-mass galaxies*

Abstract: We explore the quenching of low-mass galaxies (10 108 ) as a function of lookback time using the star formation histories (SFHs) of 38 Local Group dwarf galaxies. The SFHs were derived by analyzing color–magnitude diagrams of resolved stellar populations in archival Hubble Space Telescope/Wide Field Planetary Camera 2 imaging. We find: (1) lower-mass galaxies quench earlier than higher-mass galaxies; (2) inside of R there is no correlation between a satellite's current proximity to a massive host and its quenching epoch; and (3) there are hints of systematic differences in the quenching times of M31 and Milky Way (MW) satellites, although the sample size and uncertainties in the SFHs of M31 dwarfs prohibit definitive conclusions. Combined with results from the literature, we qualitatively consider the redshift evolution (z = 0–1) of the quenched galaxy fraction over ~7 dex in stellar mass (10 10 ). The quenched fraction of all galaxies generally increases toward the present, with both the lowest and highest-mass systems exhibiting the largest quenched fractions at all redshifts. In contrast, galaxies between 108–1010 have the lowest quenched fractions. We suggest that such intermediate-mass galaxies are the least efficient at quenching. Finally, we compare our quenching times with predictions for infall times for low-mass galaxies associated with the MW. We find that some of the lowest-mass satellites (e.g., CVn II, Leo IV) may have been quenched before infall, while higher-mass satellites (e.g., Leo I, Fornax) typically quench ~1–4 Gyr after infall.

A new compact wideband balun

Abstract: A novel wideband balun has been developed for MMIC (monolithic microwave integrated circuit) applications Simple RF reflection and coupling principles are used to achieve a wideband performance in a simple microstrip configuration The design was intended for 8- to 18-GHz wideband mixer applications According to the predicted performance the insertion loss was better than 2 dB from 7 to 19 GHz, the amplitude balance was less than 1 dB, and the phase balance was less than 5 degrees from the 180 degrees phase difference Experimental results show very good agreement with the predicted performance >

Acoustic catastrophic event detection and data capture and retrieval system for aircraft

Abstract: An acoustic sensor system is provided for detecting failures or terrorist events in commercial aviation and is adapted for assisting in the detection and post event analysis of such events. The system is adapted for use in combination with a comprehensive multi-media safety and surveillance system, utilizing both visual and audio information as well as critical data to the flight crew, and to a ground tracking station, and recording the information and data generated during flight. A plurality of acoustic sensors are strategically and systematically placed about an airframe. The sensors are adapted for communicating with a monitor/recording system and may be hard wired or utilize wireless communications therewith. In the event of a catastrophic event, such as a bomb explosion, a gunshot or structural failure an acoustic event would be recorded for later analysis.

An experimental microwave-powered helicopter

Abstract: Microwave power transmission and helicopter technologies have been successfully combined to produce a hovering vehicle which is held aloft solely by power derived from a microwave beam New, efficient, and lightweight antenna and rectifier technologies allow the helicopter to support its energy-capture system and a substantial payload in addition to its own weight Projections for further development of the device in terms of technological improvements are made