Showing papers by "Raytheon published in 2005"

Nonlinear filters: beyond the Kalman filter

Abstract: Nonlinear filters can provide estimation accuracy that is vastly superior to extended Kalman filters for some important practical applications. We compare several types of nonlinear filters, including: particle filters (PFs), unscented Kalman filters, extended Kalman filters, batch filters and exact recursive filters. The key practical issue in nonlinear filtering is computational complexity, which is often called "the curse of dimensionality". It has been asserted that PFs avoid the curse of dimensionality, but this is generally incorrect. Well-designed PFs with good proposal densities sometimes avoid the curse of dimensionality, but not otherwise. Future research in nonlinear filtering will exploit recent progress in quasi-Monte Carlo algorithms (rather than boring old Monte Carlo methods), as well as ideas borrowed from physics (e.g., dimensional interpolation) and new mesh-free adjoint methods for solving PDEs. This tutorial was written for normal engineers, who do not have nonlinear filters for breakfast.

Model predictive control: for want of a local control Lyapunov function, all is not lost

Abstract: We present stability results for unconstrained discrete-time nonlinear systems controlled using finite-horizon model predictive control (MPC) algorithms that do not require the terminal cost to be a local control Lyapunov function. The two key assumptions we make are that the value function is bounded by a K/sub /spl infin// function of a state measure related to the distance of the state to the target set and that this measure is detectable from the stage cost. We show that these assumptions are sufficient to guarantee closed-loop asymptotic stability that is semiglobal and practical in the horizon length and robust to small perturbations. If the assumptions hold with linear (or locally linear) K/sub /spl infin// functions, then the stability will be global (or semiglobal) for long enough horizon lengths. In the global case, we give an explicit formula for a sufficiently long horizon length. We relate the upper bound assumption to exponential and asymptotic controllability. Using terminal and stage costs that are controllable to zero with respect to a state measure, we can guarantee the required upper bound, but we also require that the state measure be detectable from the stage cost to ensure stability. While such costs and state measures may not be easy to construct in general, we explore a class of systems, called homogeneous systems, for which it is straightforward to choose them. In fact, we show for homogeneous systems that the associated K/sub /spl infin// functions are linear, thereby guaranteeing global asymptotic stability. We discuss two examples found elsewhere in the MPC literature, including the discrete-time nonholonomic integrator, to demonstrate our methods. For these systems, we give a new result: They can be globally asymptotically stabilized by a finite-horizon MPC algorithm that has guaranteed robustness. We also show that stable linear systems with control constraints can be globally exponentially stabilized using finite-horizon MPC without requiring the terminal cost to be a global control Lyapunov function.

Network intrusion prevention

Abstract: According to one embodiment of the invention, a system for preventing a network attack is provided. The system includes a computer having a processor and a computer-readable medium. The system also includes a shield program stored in the computer-readable medium. The shield program is operable, when executed by the processor, to transmit an agent to each of one or more nodes in a network in response to an attack directed to the network. The agent is operable to initiate a reduction of the effect of the attack on the node.

Resolving mass flux at high spatial and temporal resolution using GRACE intersatellite measurements

Abstract: [1] The GRACE mission is designed to monitor mass flux on the Earth's surface at one month and high spatial resolution through the estimation of monthly gravity fields. Although this approach has been largely successful, information at submonthly time scales can be lost or even aliased through the estimation of static monthly parameters. Through an analysis of the GRACE data residuals, we show that the fundamental temporal and spatial resolution of the GRACE data is 10 days and 400 km. We present an approach similar in concept to altimetric methods that recovers submonthly mass flux at a high spatial resolution. Using 4° × 4° blocks at 10-day intervals, we estimate the mass of surplus or deficit water over a 52° × 60° grid centered on the Amazon basin for July 2003. We demonstrate that the recovered signals are coherent and correlate well with the expected hydrological signal.

The I3RC - Bringing Together the Most Advanced Radiative Transfer Tools for Cloudy Atmospheres

Abstract: The interaction of clouds with solar and terrestrial radiation is one of the most important topics of climate research. In recent years it has been recognized that only a full three-dimensional (3D) treatment of this interaction can provide answers to many climate and remote sensing problems, leading to the worldwide development of numerous 3D radiative transfer (RT) codes. The international Intercomparison of 3D Radiation Codes (I3RC), described in this paper, sprung from the natural need to compare the performance of these 3D RT codes used in a variety of current scientific work in the atmospheric sciences. I3RC supports intercomparison and development of both exact and approximate 3D methods in its effort to 1) understand and document the errors/limits of 3D algorithms and their sources; 2) provide “baseline” cases for future code development for 3D radiation; 3) promote sharing and production of 3D radiative tools; 4) derive guidelines for 3D radiative tool selection; and 5) improve atmospheric science education in 3D RT. Results from the two completed phases of I3RC have been presented in two workshops and are expected to guide improvements in both remote sensing and radiative energy budget calculations in cloudy atmospheres.

Recent developments to the MICHELLE 2-D/3-D electron gun and collector modeling code

Abstract: Recent developments to the MICHELLE electron gun and collector design tool are reported in this paper. The MICHELLE code is a new finite-element (FE) two-dimensional and three-dimensional electrostatic particle-in-cell code that has been designed to address the recent beam optics modeling and simulation requirements for vacuum electron devices, ion sources, and charged-particle transport. Problem classes specifically targeted include depressed collectors, gridded-guns, multibeam guns, sheet-beam guns, and ion thrusters. The focus of the development program is to combine modern FE techniques with improved physics models. The code employs a conformal mesh, including both structured and unstructured mesh architectures for meshing flexibility, along with a new method for accurate, efficient particle tracking. New particle emission models for thermionic beam representation are included that support primary emission, with an advanced secondary emission model. This paper reports on three significant advances to MICHELLE over the past year; hybrid structured/unstructured mesh support, a time-domain electrostatic algorithm, and an ion plasma model with charge exchange.

Shelf-life monitoring sensor-transponder system

Abstract: A perishable integrity indicator system includes a RFID transponder and a perishable integrity sensor. The RFID transponder includes a RF integrated circuit coupled with an antenna. The sensor monitors the time and temperature of the perishable. A freshness determining module receives time- and temperature-dependent measurement data from the perishable integrity sensor and determines a current freshness status. A communications interface to the RFID transponder permits a RFID reader to retrieve current freshness status data corresponding to the freshness status determined by the freshness determining module. The system further includes a power management module.

System and method for adaptive path planning

Abstract: A path planning system and method for an object, such as a vehicle, provides a randomized adaptive path planning from starting position (RN) to a goal posotion (202) that handles real-time path planning for a vehicle operating under kinodynamic constraints in dynamically changing and uncertain environments with probabilistic knowledge of vehicle and obstacle (204a-f) movement

An intelligently controlled RF power amplifier with a reconfigurable MEMS-varactor tuner

Abstract: This paper presents an intelligently controlled RF power amplifier with a reconfigurable output tuner using microelectromechanical system (MEMS) switches and a varactor. By switching on/off the MEMS switches and varying the bias voltage of the varactor, the performance of the amplifier is optimized for input signals with known or unknown frequencies in a range of 8-12 GHz. Fabrication-related unit-to-unit variations of the amplifier are overcome by the reconfigurable tuner. Directed algorithms based on a characterization table and on black-box genetic algorithms are developed for optimization and search.

Reflect array antennas having monolithic sub-arrays with improved DC bias current paths

Abstract: Embodiments of active array antennas are generally described herein. Other embodiments may be described and claimed. In some embodiments, a reflect array antenna includes an array of rectangular monolithic sub-array modules arranged in a non-uniform pattern to leave a plurality of rectangular gaps in the pattern. A DC feed pin located within each gap may provide DC bias current to the sub-array modules. The sub-array modules may be mounted on a heat sink in the non-uniform pattern. The heat sink may have holes aligned with the gaps to allow passage of the DC feed pins. In some embodiments, an array cooling assembly may be coupled to the back of the heat sink to cool the reflect array antenna with a coolant.

Electronic sight for firearm, and method of operating same

Abstract: A firearm sight receives information regarding a factor, and then automatically adjusts the relative positions of a digital reticle and an image on a viewing section to compensate for the influence of the factor on a projectile trajectory. A different feature involves automatically adjusting a characteristic of the reticle based on the image. Another feature involves automatically adjusting the digital image to distinguish a portion thereof aligned with the reticle from an adjacent portion thereof. Yet another feature involves causing the firearm sight to generate an audible sound. Still another feature involves presenting information on the viewing section which represents the position of the firearm sight on the surface of the earth.

System and method to increase network throughput

Abstract: Data flows in a network are managed by dynamically determining bandwidth usage and available bandwidth for IP-ABR service data flows and dynamically allocating a portion of the available bandwidth to the IP-ABR data flows. Respective bandwidth requests from network hosts are received and an optimal window size for a sender host is determined based upon bandwidth allocated for the data flow and a round trip time of a segment to provide self-pacing of the data flow.

Search for gravitational waves from galactic and extra-galactic binary neutron stars

Abstract: We use 373 hours (≈15 days) of data from the second science run of the LIGO gravitational-wave detectors to search for signals from binary neutron star coalescences within a maximum distance of about 1.5 Mpc, a volume of space which includes the Andromeda Galaxy and other galaxies of the Local Group of galaxies. This analysis requires a signal to be found in data from detectors at the two LIGO sites, according to a set of coincidence criteria. The background (accidental coincidence rate) is determined from the data and is used to judge the significance of event candidates. No inspiral gravitational-wave events were identified in our search. Using a population model which includes the Local Group, we establish an upper limit of less than 47 inspiral events per year per Milky Way equivalent galaxy with 90% confidence for nonspinning binary neutron star systems with component masses between 1 and 3M⊙.

Joint Strategy Fictitious Play with Inertia for Potential Games

Abstract: We consider finite multi-player repeated games involving a large number of players with large strategy spaces and enmeshed utility structures. In these "large-scale" games, players are inherently faced with limitations in both their observational and computational capabilities. Accordingly, players in large-scale games need to make their decisions using algorithms that accommodate limitations in information gathering and processing. A motivating example is a congestion game in a complex transportation system, in which a large number of vehicles make daily routing decisions to optimize their own objectives in response to their observations. In this setting, observing and responding to the individual actions of all vehicles on a daily basis would be a formidable task for any individual driver. This disqualifies some of the well known decision making models such as "Fictitious Play" (FP) as suitable models for driver routing behavior. A more realistic assumption on the information tracked and processed by an individual driver is the daily aggregate congestion on the specific roads that are of interest to that driver. We will show that Joint Strategy Fictitious Play (JSFP), a close variant of FP, accommodates such information aggregation. Furthermore, we establish the convergence of JSFP to a pure Nash equilibrium in congestion games, or equivalently in finite potential games, when players use some inertia in their decisions and in both cases of with or without exponential discounting of the historical data.

Fault tolerance and recovery in a high-performance computing (HPC) system

Abstract: In one embodiment, a method for fault tolerance and recovery in a high-performance computing (HPC) system includes monitoring a currently running node in an HPC system including multiple nodes. A fabric coupling the multiple nodes to each other and coupling the multiple nodes to storage accessible to each of the multiple nodes and capable of storing multiple hosts that are each executable at any of the multiple nodes. The method includes, if a fault occurs at the currently running node, discontinuing operation of the currently running node and booting the host at a free node in the HPC system from the storage.

A gas turbine engine frame with an integral fluid reservoir and air/fluid heat exchanger

Abstract: Disclosed is a structural frame (38) for a gas turbine (10) engine comprising an integral fluid reservoir (60) and air/fluid heat exchanger (68;168;268). A central hub (56) includes a reservoir (60) for storing a fluid and an outer rim (62) circumscribes the hub (56). A heat exchanger (68;168;268) is fluidly coupled to the reservoir (60) and is in simultaneous communication with the fluid and an air stream.

Scheduling in a high-performance computing (hpc) system

Abstract: In one embodiment, a method for scheduling in a high-performance computing (HPC) system includes receiving a call from a management engine that manages a cluster of nodes in the HPC system. The call specifies a request including a job for scheduling. The method further includes determining whether the request is spatial, compact, or nonspatial and noncompact. The method further includes, if the request is spatial, generating one or more spatial combinations of nodes in the cluster and selecting one of the spatial combinations that is schedulable. The method further includes, if the request is compact, generating one or more compact combinations of nodes in the cluster and selecting one of the compact combinations that is schedulable. The method further includes, if the request is nonspatial and noncompact, identifying one or more schedulable nodes and generating a nonspatial and noncompact combination of nodes in the cluster.

An approach to using snow areal depletion curves inferred from MODIS and its application to land surface modelling in Alaska

Abstract: Snowcover areal depletion curves inferred from the moderate resolution imaging spectroradiometer (MODIS) are validated and then applied in NASA’s catchment-based land surface model (CLSM) for numerical simulations of hydrometeorological processes in the Kuparuk River basin (KRB) of Alaska. The results demonstrate that the MODIS snowcover fraction f derived from a simple relationship in terms of the normalized difference snow index compares well with Landsat values over the range 20 � f � 100%. For f< 20%, however, MODIS 500 m subpixel data underestimate the amount of snow by up to 13% compared with Landsat at spatial resolutions of 30 m binned to equivalent 500 m pixels. After a bias correction, MODIS snow areal depletion curves during the spring transition period of 2002 for the KRB exhibit similar features to those derived from surface-based observations. These results are applied in the CLSM subgrid-scale snow parameterization that includes a deep and a shallow snowcover fraction. Simulations of the evolution of the snowpack and of freshwater discharge rates for the KRB over a period of 11 years are then analysed with the inclusion of this feature. It is shown that persistent snowdrifts on the arctic landscape, associated with a secondary plateau in the snow areal depletion curves, are hydrologically important. An automated method is developed to generate the shallow and deep snowcover fractions from MODIS snow areal depletion curves. This provides the means to apply the CLSM subgrid-scale snow parameterization in all watersheds subject to seasonal snowcovers. Improved simulations and predictions of the global surface energy and water budgets are expected with the incorporation of the MODIS snow data into the CLSM. Copyright  2005 John Wiley & Sons, Ltd.

Search for gravitational waves from primordial black hole binary coalescences in the galactic halo

Abstract: We use data from the second science run of the LIGO gravitational-wave detectors to search for the gravitational waves from primordial black hole binary coalescence with component masses in the range 0.2–1.0M⊙. The analysis requires a signal to be found in the data from both LIGO observatories, according to a set of coincidence criteria. No inspiral signals were found. Assuming a spherical halo with core radius 5 kpc extending to 50 kpc containing nonspinning black holes with masses in the range 0.2–1.0M⊙, we place an observational upper limit on the rate of primordial black hole coalescence of 63 per year per Milky Way halo (MWH) with 90% confidence.

First all-sky upper limits from LIGO on the strength of periodic gravitational waves using the Hough transform

Abstract: We perform a wide parameter-space search for continuous gravitational waves over the whole sky and over a large range of values of the frequency and the first spin-down parameter. Our search method is based on the Hough transform, which is a semicoherent, computationally efficient, and robust pattern recognition technique. We apply this technique to data from the second science run of the LIGO detectors and our final results are all-sky upper limits on the strength of gravitational waves emitted by unknown isolated spinning neutron stars on a set of narrow frequency bands in the range 200–400 Hz. The best upper limit on the gravitational-wave strain amplitude that we obtain in this frequency range is 4.43×10^(-23).

Multimodal biometric identification for large user population using fingerprint, face and iris recognition

Abstract: Biometric systems based solely on one-modal biometrics are often not able to meet the desired performance requirements for large user population applications, due to problems such as noisy data, intra-class variations, restricted degrees of freedom, nonuniversity, spoof attacks, and unacceptable error rates. Multimodal biometrics refers to the use of a combination of two or more biometric modalities in a single identification system. The most compelling reason to combine different modalities is to improve the recognition accuracy. This can be done when features of different biometrics are statistically independent. This paper overviews and discusses the various scenarios that are possible in multimodal biometric systems using fingerprint, face and iris recognition, the levels of fusion that are possible and the integration strategies that can be adopted to fuse information and improve overall system accuracy. This paper also discusses how the image quality of fingerprint, face and iris used in the multimodal biometric systems affects the overall identification accuracy and the need of staffing for the secondary human validation. For a large user population identification system, which often has more than tens or hundreds of millions of subject images already enrolled in the matcher databases and has to process more than hundreds of thousands of identification requests, the system's identification accuracy and the need of staffing levels to properly operate the system are two of the most important factors in determining whether a system is properly designed and integrated

Programmable cockpit upgrade system

Abstract: Disclosed is a programmable computing and display device (14) for upgrading a cockpit instrument panel (12) of an aircraft (8). The programmable computing and display device includes a plurality of processing units; a network backbone (50) that establishes a network among the processing units for the exchange of network data traffic; at least one display (16) to display video graphics to a cockpit crew member; and a modular assembly (17) that retains the processing units, the network backbone and the display.

Upper limits on gravitational wave bursts in LIGO's second science run

Abstract: We perform a search for gravitational wave bursts using data from the second science run of the LIGO detectors, using a method based on a wavelet time-frequency decomposition. This search is sensitive to bursts of duration much less than a second and with frequency content in the 100–1100 Hz range. It features significant improvements in the instrument sensitivity and in the analysis pipeline with respect to the burst search previously reported by LIGO. Improvements in the search method allow exploring weaker signals, relative to the detector noise floor, while maintaining a low false alarm rate, O(0.1) μHz. The sensitivity in terms of the root-sum-square (rss) strain amplitude lies in the range of hrss∼10-20-10-19 Hz-1/2. No gravitational wave signals were detected in 9.98 days of analyzed data. We interpret the search result in terms of a frequentist upper limit on the rate of detectable gravitational wave bursts at the level of 0.26 events per day at 90% confidence level. We combine this limit with measurements of the detection efficiency for selected waveform morphologies in order to yield rate versus strength exclusion curves as well as to establish order-of-magnitude distance sensitivity to certain modeled astrophysical sources. Both the rate upper limit and its applicability to signal strengths improve our previously reported limits and reflect the most sensitive broad-band search for untriggered and unmodeled gravitational wave bursts to date.

Evolving cooperative strategies for UAV teams

Abstract: We present a Genetic Programming approach to evolve cooperative controllers for teams of UAVs. Our focus is a collaborative search mission in an uncertain and/or hostile environment. The controllers are decision trees constructed from a set of low-level functions. Evolved decision trees are robust to changes in initial mission parameters and approach the optimal bound for time-to-completion. We compare results between steady-state and generational approaches, and examine the effects of two common selection operators.

Centralizer-based survey and navigation device and method

Abstract: A Centralizer based Survey and Navigation (CSN) device designed to provide borehole or passageway position information The CSN device can include one or more displacement sensors, centralizers, an odometry sensor, a borehole initialization system, and navigation algorithm implementing processor(s) Also, methods of using the CSN device for in-hole survey and navigation

Method and apparatus for cooling with coolant at a subambient pressure

Abstract: According to one embodiment, an apparatus includes a fluid coolant and structure which reduces a pressure of the fluid coolant through a subambient pressure at which the coolant has a cooling temperature less than a temperature of the heat-generating structure. The apparatus also includes structure that directs a flow of the fluid coolant in the form of a liquid at a subambient pressure in a manner causing the liquid coolant to be brought into thermal communication with the heat-generating structure. The heat from the heat-generating structure causes the liquid coolant to boil and vaporize so that the coolant absorbs heat from the heat-generating structure as the coolant changes state. The structure is configured to circulate the fluid coolant through a flow loop while maintaining the pressure of the fluid coolant within a range having an upper bound less than ambient pressure. The apparatus also includes a first heat exchanger for exchanging heat between the fluid coolant flowing through the loop and a second coolant in an intermediary loop so as to condense the fluid coolant flowing through the loop to a liquid. The apparatus also includes a second heat exchanger for exchanging heat between the second coolant in the intermediary cooling loop and a body of water on which the ship is disposed.

Upper limits from the LIGO and TAMA detectors on the rate of gravitational-wave bursts

Abstract: We report on the first joint search for gravitational waves by the TAMA and LIGO collaborations. We looked for millisecond-duration unmodeled gravitational-wave bursts in 473 hr of coincident data collected during early 2003. No candidate signals were found. We set an upper limit of 0.12 events per day on the rate of detectable gravitational-wave bursts, at 90% confidence level. From software simulations, we estimate that our detector network was sensitive to bursts with root-sum-square strain amplitude above approximately 1–3×10-19 Hz-1/2 in the frequency band 700-2000 Hz. We describe the details of this collaborative search, with particular emphasis on its advantages and disadvantages compared to searches by LIGO and TAMA separately using the same data. Benefits include a lower background and longer observation time, at some cost in sensitivity and bandwidth. We also demonstrate techniques for performing coincidence searches with a heterogeneous network of detectors with different noise spectra and orientations. These techniques include using coordinated software signal injections to estimate the network sensitivity, and tuning the analysis to maximize the sensitivity and the livetime, subject to constraints on the background.

The Mass Function of Void Galaxies in the Sloan Digital Sky Survey Data Release 2

Abstract: We estimate the mass function of void galaxies in the second public data release of the Sloan Digital Sky Survey from a sample of 1000 galaxies with local density contrasts of ?v < -0.6. The galaxy sample is split into ellipticals and spirals using a color-S?rsic index criterion. We estimate the virial masses of ellipticals using the measured spectral line widths along with the observed size. Projection effects and uncertainties in halo properties make mass estimates of spirals more difficult. We use an inversion of the Tully-Fisher relation to estimate the isothermal rotational velocity and introduce a scaling factor to estimate the halo extent. We then fit the measured mass function against a theoretical Press-Schechter model and find that the distribution of galaxies in voids appears to be nearly unbiased compared to the mass.

A spatially continuous magnetization model for Mars

Abstract: [1] Using a three-component magnetic field data set at over 100,000 satellite points previously compiled for spherical harmonic analysis, we have produced a continuously varying magnetization model for Mars. The magnetized layer was assumed to be 40 km thick, an average value based on previous studies of the topography and gravity field. The severe nonuniqueness in magnetization modeling is addressed by seeking the model with minimum root-mean-square (RMS) magnetization for a given fit to the data, with the trade-off between RMS magnetization and fit controlled by a damping parameter. Our preferred model has magnetization amplitudes up to 20 A/m. It is expressed as a linear combination of the Green's functions relating each observation to magnetization at the point of interest within the crust, leading to a linear system of equations of dimension the number of data points. Although this is impractically large for direct solution, most of the matrix elements relating data to model parameters are negligibly small. We therefore apply methods applicable to sparse systems, allowing us to preserve the resolution of the original data set. Thus we produce more detailed models than any previously published, although they share many similarities. We find that tectonism in the Valles Marineris region has a magnetic signature, and we show that volcanism south of the dichotomy boundary has both a magnetic and gravity signature. The method can also be used to downward continue magnetic data, and a comparison with other leveling techniques at Mars' surface is favorable.