Showing papers by "Raytheon published in 2004"

The Infrared Array Camera (IRAC) for the Spitzer Space Telescope

Abstract: The Infrared Array Camera (IRAC) is one of three focal plane instruments on the Spitzer Space Telescope. IRAC is a four-channel camera that obtains simultaneous broadband images at 3.6, 4.5, 5.8, and 8.0 � m. Two nearly adjacent 5A2 ; 5A2 fields of view in the focal plane are viewed by the four channels in pairs (3.6 and 5.8 � m; 4.5 and 8 � m). All four detector arrays in the camera are 256 ; 256 pixels in size, with the two shorter wavelength channels using InSb and the two longer wavelength channels using Si:As IBC detectors. IRAC is a powerful survey instrument because of its high sensitivity, large field of view, and four-color imaging. This paper summarizes the in-flight scientific, technical, and operational performance of IRAC.

Multiple hypothesis tracking for multiple target tracking

Abstract: Multiple hypothesis tracking (MHT) is generally accepted as the preferred method for solving the data association problem in modern multiple target tracking (MTT) systems. This paper summarizes the motivations for MHT, the basic principles behind MHT and the alternative implementations in common use. It discusses the manner in which the multiple data association hypotheses formed by MHT can be combined with multiple filter models, such as used by the interacting multiple model (IMM) method. An overview of the studies that show the advantages of MHT over the conventional single hypothesis approach is given. Important current applications and areas of future research and development for MHT are discussed.

The Thermal Emission Imaging System (THEMIS) for the Mars 2001 Odyssey mission

Abstract: The Thermal Emission Imaging System (THEMIS) on 2001 Mars Odyssey will investigate the surface mineralogy and physical properties of Mars using multi-spectral thermal-infrared images in nine wavelengths centered from 6.8 to 14.9 μm, and visible/near-infrared images in five bands centered from 0.42 to 0.86 μm. THEMIS will map the entire planet in both day and night multi-spectral infrared images at 100-m per pixel resolution, 60% of the planet in one-band visible images at 18-m per pixel, and several percent of the planet in 5-band visible color. Most geologic materials, including carbonates, silicates, sulfates, phosphates, and hydroxides have strong fundamental vibrational absorption bands in the thermal-infrared spectral region that provide diagnostic information on mineral composition. The ability to identify a wide range of minerals allows key aqueous minerals, such as carbonates and hydrothermal silica, to be placed into their proper geologic context. The specific objectives of this investigation are to: (1) determine the mineralogy and petrology of localized deposits associated with hydrothermal or sub-aqueous environments, and to identify future landing sites likely to represent these environments; (2) search for thermal anomalies associated with active sub-surface hydrothermal systems; (3) study small-scale geologic processes and landing site characteristics using morphologic and thermophysical properties; and (4) investigate polar cap processes at all seasons. THEMIS follows the Mars Global Surveyor Thermal Emission Spectrometer (TES) and Mars Orbiter Camera (MOC) experiments, providing substantially higher spatial resolution IR multi-spectral images to complement TES hyperspectral (143-band) global mapping, and regional visible imaging at scales intermediate between the Viking and MOC cameras.

ZnO nanowire growth and devices

Abstract: The large surface area of ZnO nanorods makes them attractive for gas and chemical sensing, and the ability to control their nucleation sites makes them candidates for micro-lasers or memory arrays. In addition, they might be doped with transition metal (TM) ions to make spin-polarized light sources. To date, most of the work on ZnO nanostructures has focused on the synthesis methods and there have been only a few reports of the electrical characteristics. We review fabrication methods for obtaining device functionality from single ZnO nanorods. A key aspect is the use of sonication to facilitate transfer of the nanorods from the initial substrate on which they are grown to another substrate for device fabrication. Examples of devices fabricated using this method are briefly described, including metal-oxide semiconductor field effect depletion-mode transistors with good saturation behavior, a threshold voltage of ∼−3 V and a maximum transconductance of order 0.3 mS/mm and Pt Schottky diodes with excellent ideality factors of 1.1 at 25 °C and very low (1.5 × 10 −10 A, equivalent to 2.35 A cm −2 , at −10 V) reverse currents. The photoresponse showed only a minor component with long decay times (tens of seconds) thought to originate from surface states. These results show the ability to manipulate the electron transport in nanoscale ZnO devices.

Work characteristics and employee health and well-being: Test of a model of healthy work organization.

Abstract: This paper presents an initial test and validation of a model of healthy work organization. A questionnaire based on the proposed model was completed by 1,130 employees of a national retailer. The instrument measured 29 first-order constructs underlying the six higher-order domains of the model. The overall model fit and relationships among the second-order factors were examined using AMOS structural equation-modelling procedures. The structural analyses presented here support the proposed model. An acceptable overall fit was demonstrated, and all second-order, and second- to first-order, relationships were significant. Employees' perceptions of their organization affect their perception of the climate, which impacts the way people relate to their job and see their future in the organization, ultimately impacting their work adjustment, health and well-being. This model has implications for both research and practice.

Closed-loop control over wireless networks

Abstract: This article includes an implementation of an 802.11b wireless control loop with high communication rates and a timing scheme that uses clock driven sensing and actuation with event-driven control. The timing scheme was implemented using standard PCs and an 802.11b peer-to-peer wireless network. The control scheme was scaled up to a multimode multiplant arrangement with coordination among loops. To examine the wireless control loop performance, we use the rotating base variation of the linear inverted pendulum. Using the wireless control loop, we can examine a number of the characteristics of UDP data transmission over 802.11b.

Detector description and performance for the first coincidence observations between LIGO and GEO

Abstract: For 17 days in August and September 2002, the LIGO and GEO interferometer gravitational wave detectors were operated in coincidence to produce their first data for scientific analysis. Although the detectors were still far from their design sensitivity levels, the data can be used to place better upper limits on the flux of gravitational waves incident on the earth than previous direct measurements. This paper describes the instruments and the data in some detail, as a companion to analysis papers based on the first data.

Vacuum package fabrication of integrated circuit components

Abstract: A method for manufacturing integrated circuit device lids includes creating a lid cavity on the surface of a lid wafer, forming a sealing surface on the lid wafer that surrounds the lid cavity, and forming a trench on the lid wafer between the lid cavity and the sealing surface. The resulting structure uptakes excess sealing surface material and prevents such material from entering the lid cavity.

A parallel electromagnetic genetic-algorithm optimization (EGO) application for patch antenna design

Abstract: In this paper, we describe an electromagnetic genetic algorithm (GA) optimization (EGO) application developed for the cluster supercomputing platform. A representative patch antenna design example for commercial wireless applications is detailed, which illustrates the versatility and applicability of the method. We show that EGO allows us to combine the accuracy of full-wave EM analysis with the robustness of GA optimization and the speed of a parallel computing algorithm. A representative patch antenna design case study is presented. We illustrate the use of EGO to design a dual-band antenna element for wireless communication (1.9 and 2.4 GHz) applications. The resulting antenna exhibits acceptable dual-band operation (i.e., better than -10 dB return loss with 5.3 and 7% operating bandwidths at 1.9 and 2.4 GHz) while maintaining a cross-pol maximum field level at least 11 dB below the co-pol maximum.

Transverse device array radiator ESA

Abstract: An antenna array employing continuous transverse stubs as radiating elements is described, which includes an upper conductive plate structure comprising a set of continuous transverse stubs, and a lower conductive plate structure disposed in a spaced relationship relative to the upper plate structure. The upper plate structure and the lower plate structure define an overmoded waveguide medium for propagation of electromagnetic energy. For each of the stubs, one or more transverse device array phase shifters are disposed therein.

Global change in the thermosphere: Compelling evidence of a secular decrease in density

Abstract: [1] We derive secular trends in upper thermospheric density from the historical orbital elements of 27 long-lived, near-Earth space objects. The results cover all levels of solar activity during the period 1996–2001, and each object indicates a long-term decrease of total mass density. The observed trends increase with increasing height from 200–700 km and are largest for solar minimum conditions; average values range from −2% to −5% per decade. The trends are largely independent of geomagnetic activity, local time, latitude, and season. We examine several possible sources of error in our results and conclude that none of them can individually account for the observed trends. The trends that we obtain are qualitatively, and in some cases quantitatively, consistent with available theoretical predictions of density decreases associated with the cooling effect of increased greenhouse gas concentrations.

MMW electronically scanned antenna

Abstract: A millimeter wave (MMW) antenna array includes a continuous transverse stub (CTS) radiating aperture comprising a set of spaced continuous transverse stubs, each having a longitudinal extent. A series feed system is coupled to an excitation source for exciting the stubs with MMW electromagnetic energy having a linear phase progression along the longitudinal extent of the stubs to produce an array beam which can be scanned over a beam scan range by changing the excitation frequency.

North Alabama Lightning Mapping Array (LMA): VHF Source Retrieval Algorithm and Error Analyses

Abstract: Two approaches are used to characterize how accurately the north Alabama Lightning Mapping Array (LMA) is able to locate lightning VHF sources in space and time The first method uses a Monte Carlo computer simulation to estimate source retrieval errors The simulation applies a VHF source retrieval algorithm that was recently developed at the NASA Marshall Space Flight Center (MSFC) and that is similar, but not identical to, the standard New Mexico Tech retrieval algorithm The second method uses a purely theoretical technique (ie, chi-squared Curvature Matrix Theory) to estimate retrieval errors Both methods assume that the LMA system has an overall rms timing error of 50 ns, but all other possible errors (eg, anomalous VHF noise sources) are neglected The detailed spatial distributions of retrieval errors are provided Even though the two methods are independent of one another, they nevertheless provide remarkably similar results However, altitude error estimates derived from the two methods differ (the Monte Carlo result being taken as more accurate) Additionally, this study clarifies the mathematical retrieval process In particular, the mathematical difference between the first-guess linear solution and the Marquardt-iterated solution is rigorously established thereby explaining why Marquardt iterations improve upon the linear solution

The Third VLBA Calibrator Survey

Abstract: This paper presents the third extension to the Very Large Baseline Array (VLBA) Calibrator Survey, containing 360 new sources not previously observed with very long baseline interferometry (VLBI). The survey, based on three 24 hour VLBA observing sessions, fills the areas on the sky above declination -45 degrees where the calibrator density is less than one source within a 4 degrees radius disk at any given direction. The positions were derived from astrometric analysis of the group delays determined at 2.3 and 8.6 GHz frequency bands using the Calc/Solve software package. The VCS3 catalogue of source positions, plots of correlated flux density versus the length of projected baseline, contour plots and fits files of naturally weighted CLEAN images as well as calibrated visibility function files are available on the Web at this http URL

Multispectral imaging chip using photonic crystals

Abstract: On-chip multispectral imaging and data management is provided in the form of an Adaptive Focal Plane Array (AFPA) that is capable of spectral tunability at the pixel level. Layers of photonic crystals are registered with pixels of a broadband focal plane array. Spectral tuning is accomplished by switching the photonic crystal layers on/off and/or by changing their material structure to tune their photonic band gaps and provide a passband for incident photons. The photonic crystal layers are preferably segmented to independently address different regions or “cells” of pixels down to a pixel-by-pixel resolution. The AFPA may simultaneously sense different regions of a scene at different spectral wavelengths, spatial resolutions and sensitivities.

Self-organized coherence in fiber laser arrays

Abstract: Self-organized coherence between fiber lasers has been reported both via all-fiber 2x2 directional coupler trees and in spatially multi-core fibers. We have taken this a major step forward, coupling together a number of independent fiber lasers to obtain a spatially and spectrally coherent far field, with no active length, polarization, or amplitude control. The near field output comes from a spatial array rather than from a single fiber, making this approach scalable to extremely high power.

HgCdTe focal plane arrays for dual-color mid- and long-wavelength infrared detection

Abstract: Raytheon Vision Systems (RVS, Goleta, CA) in collaboration with HRL Laboratories (Malibu, CA) is contributing to the maturation and manufacturing readiness of third-generation, dual-color, HgCdTe infrared staring focal plane arrays (FPAs). This paper will highlight data from the routine growth and fabrication of 256×256 30-µm unit-cell staring FPAs that provide dual-color detection in the mid-wavelength infrared (MWIR) and long wavelength infrared (LWIR) spectral regions. The FPAs configured for MWIR/MWIR, MWIR/LWIR, and LWIR/LWIR detection are used for target identification, signature recognition, and clutter rejection in a wide variety of space and ground-based applications. Optimized triple-layer heterojunction (TLHJ) device designs and molecular beam epitaxy (MBE) growth using in-situ controls has contributed to individual bands in all dual-color FPA configurations exhibiting high operability (>99%) and both performance and FPA functionality comparable to state-of-the-art, single-color technology. The measured spectral cross talk from out-of-band radiation for either band is also typically less than 10%. An FPA architecture based on a single-mesa, single-indium bump, and sequential-mode operation leverages current single-color processes in production while also providing compatibility with existing second-generation technologies.

Weapon sight with ballistics information persistence

Abstract: A device can be supported on a weapon, and has a range portion that specifies a range to a target, a sensor portion that provides sensor information representing an orientation of the device; and a sight that facilitates weapon orientation in preparation to fire the munition. The device has an electronic control portion responsive to sensor information from the sensor portion and a range from the range portion for calculating how to hit a target with a munition, and for causing the sight to present a visual indication of how to orient the weapon so that the munition will hit the target, the electronic control portion terminating the presentation of the visual indication by the sight in response to a lack of user activity for a selected time interval during the presentation of the visual indication.

Licensed driver detection for high occupancy toll lane qualification

Abstract: A method for collecting tolls on a high occupancy toll lane includes detecting a number of driver's licenses inserted into a card reader located in a vehicle and transmitting the number of driver's licenses to a roadside transceiver for a determination of a toll amount for the vehicle based on the number of driver's licenses A transponder for use with the method includes a card reader for reading information from one or more driver's licenses inserted into the card reader and a processor operative to generate a licensed driver count related to the number of driver's licenses inserted into the card reader In one embodiment, the processor is operative to determine whether or not a driver's license is valid and the licensed driver count is indicative of the number of valid driver's licenses inserted into the card reader

Temperature tolerant vane assembly

Abstract: A vane assembly 10 suitable for a turbine engine features a refractory vane 12 with an internal cavity 20 and a pair of flexible metallic baffles 26 extending into the cavity from spanwisely opposite ends of the vane. A rigid fastener 48 , such as a nut and bolt assembly applies a tensile load to the baffles. The tensile load is reacted out as a compressive load applied to the vane. In another embodiment, the baffle is relatively rigid but the fastener is flexible. The compressive loading exerted on the vane counteracts the brittleness customarily exhibited by refractory materials and imparts damage tolerance to the vane. The arrangement also allows the use of a metal baffle that can be easily secured to the vane and dispenses with any need for a potentially troublesome seal between the baffles and the spanwise extremities of the vane.

Fluid mixer with an integral fluid capture ducts forming auxiliary secondary chutes at the discharge end of said ducts

Abstract: A fluid mixer for mixing two fluid streams 40, 42 includes a set of main lobes 26 defining alternating primary and secondary main chutes 30, 32, one or more auxiliary lobes 28 intermediate two of the main lobes, and an auxiliary fluid capture duct 62. The auxiliary lobes are defined, at least in part, by the discharge end of the duct. In operation, the duct conveys secondary fluid to secondary chutes 36 defined by the lobes thereby improving the performance of the mixer despite the presence of an obstruction 18 that would otherwise impede thorough mixing of two fluid streams.

System and method for locating a target and guiding a vehicle toward the target

Abstract: A vehicle guidance system (10). The system (10) includes a first mechanism (34, 38, 40) for tracking a vehicle (20) based on time-of-arrival information associated with energy (54) emanating from the vehicle (20) and providing vehicle position information in response thereto. A second mechanism (40, 46) steers the vehicle (20) based on the vehicle position information. In a specific embodiment, the system (10) of further includes a third mechanism (24, 28, 36, 38) for locating the target (22) based on time-of-arrival information associated with energy (52) radiating from the target (22) and providing target location information in response thereto. The second the second mechanism steers the vehicle (20) based on the target location information and the vehicle position information.

Robust linear anti‐windup synthesis for recovery of unconstrained performance

Abstract: Fixed order anti-windup augmentation is addressed by considering the dynamics of the mismatch between the constrained and unconstrained responses. The method utilizes LMIs, and the result parallels other recent LMI-based anti-windup synthesis methods. Robustness is directly addressed—which is not done in previous LMI work on anti-windup. An optimal LMI-based synthesis procedure is provided for static and plant-order linear anti-windup augmentation and the performance of the resulting design strategy is shown via a simulation example. Copyright © 2004 John Wiley & Sons, Ltd.

Weapon sight having analog on-target indicators

Abstract: A device has structure that can support the device on a weapon, and a range portion that specifies a range to a target. A sensor portion provides sensor information representing an orientation of the device, and an electronic control portion is responsive to sensor information from the sensor portion and a range from the range portion for calculating how to hit the target with a munition. The device includes a sight that facilitates weapon orientation in preparation to fire the munition, the sight having an analog indicator that is disposed within its field of view and that is responsive to the electronic control portion for indicating how to orient the weapon so that the munition will hit the target.