Smith S.M.,L3 Communications Inc. |
Furse C.,University of Utah
IEEE Transactions on Antennas and Propagation | Year: 2012
This paper describes a new stochastic finite difference time domain (S-FDTD) method for calculating the variance in the electromagnetic fields caused by variability or uncertainty in the electrical properties of the materials in the model. Details of the 1D derivation using truncated Taylor series approximations are given. The S-FDTD analysis is then compared to Monte Carlo analysis for a 1D bioelectromagnetic example. The accuracy of the method is controlled by the approximations for the cross correlations of the fields and electrical properties. In this paper, we are able to bound the variance using cross correlations of 1 (overestimate) and the reflection coefficient (underestimate). © 1963-2012 IEEE.
Pigg S.,L3 Communications Inc. |
Bodson M.,University of Utah
Asian Journal of Control | Year: 2013
This paper is concerned with the rejection of sinusoidal disturbances of unknown frequency acting at the output of unknown plants. Disturbance rejection is based on an adaptive harmonic steady-state (ADHSS) algorithm combined with a magnitude/phase locked-loop (MPLL) frequency estimator. The harmonic steady-state method assumes that the plant can be approximated by its steady-state frequency response. For high-order plants such as those encountered in active noise and vibration control (ANVC), this assumption greatly reduces the number of parameters and enables online estimation of the plant response using simple algorithms. The paper shows that when the MPLL is integrated with the ADHSS algorithm, the two components work together in such a way that the control input does not prevent frequency tracking by the MPLL, and so that the order of the ADHSS can be reduced. Thus, the addition of the MPLL allows disturbances of unknown frequency to be considered without significantly increasing the complexity of the original ADHSS. After analyzing the reduced-order ADHSS in the ideal case, the equations describing the complete system are considered. The theory of averaging is used to gain insight into the steady-state behavior of the algorithm. It is found that the system has a two-dimensional equilibrium surface such that the disturbance is cancelled exactly. A subset of the surface is proved to be locally stable. Extensive active noise control experiments demonstrate the performance of the algorithm, even when disturbance and plant parameters are changing. © 2012 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society.
Drews F.A.,L3 Communications Inc. |
Musters A.,L3 Communications Inc.
International Journal of Human Computer Studies | Year: 2015
Abstract Two experiments used a spatial navigation task to study the relationship between individual differences in working memory capacity and interrupted task performance. The results of experiment one show that participants with low working memory capacity (WMC) are more susceptible to the negative effects of interruptions than participants with high WMC. The results of additional analyses indicate that both groups differ in their strategies used to memorize material from the primary task. A second experiment manipulated memory strategy use for high and low memory span participants and found that low span participants performed at the level of high spans when using a strategy that is more typically used by high span participants. However, this performance improvement did not show during interrupted tasks. Overall, these results suggest that individual memory capacity differences affect performance during interrupted tasks by determining selection of memory strategies and by limiting performance of participants. © 2015 Elsevier Ltd. All rights reserved.
L3 Communications Inc. | Date: 2015-04-28
L3 Communications Inc. | Date: 2014-09-11
an x-ray unit for bags, parcels, boxes, and containers used to detect contraband and threats at facility checkpoints and mail and freight shipping facilities PROSCAN.
L3 Communications Inc. | Date: 2016-05-06
baggage handling and explosion detection systems comprised of computers and scanners for use by airlines and other forms of public transportation.
L3 Communications Inc. | Date: 2014-01-23
computer software which presents cargo screening data and images from different cargo inspection stations to a user.
L3 Communications Inc. | Date: 2015-09-30
x-ray scanning apparatus for non-medical purposes, namely, for screening bags, parcels, boxes, and containers used to detect contraband and threats at facilities checkpoints and mail and freight shipping.
L3 Communications Inc. | Date: 2015-07-30
L3 Communications Inc. | Date: 2012-01-24
The present invention provides a system and method for displaying exocentric views of an aircraft in a three-dimensional manner, wherein a pilot, or other user, can select from a plurality of different exocentric viewpoints. The user can thus see a three-dimensional rendering of the terrain, obstacles, and/or other images around the aircraft from vantage points other than the egocentric vantage point of most aircraft display systems. This enables the pilot to easily increase his or her situational awareness.