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Hazard alerting using line-of-sight rate

August 18, 2008
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Conference Paper
Author:
Mykel J. Kochenderfer
…
Published in:
AIAA Guidance, Navigation, and Control Conf., 18-21 August 2008.
Topic:
collision avoidance
R&D area:
R&D group:

Summary

This paper presents an analysis of an electro-optical hazard alerting system based on intruder line-of-sight rate. We use a recently-developed airspace encounter model to analyze intruder line-of-sight rate behavior prior to near miss. We look at a simple hazard alerting system that alerts whenever the line-of-sight rate drops below some set threshold. Simulations demonstrate that such an approach, regardless of the chosen threshold, leads to frequent false alerts. We explain how the problem of hazard alerting can also be formulated as a partially observable Markov decision process (POMDP) and show how such an approach significantly decreases the false alert rate.
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Summary

This paper presents an analysis of an electro-optical hazard alerting system based on intruder line-of-sight rate. We use a recently-developed airspace encounter model to analyze intruder line-of-sight rate behavior prior to near miss. We look at a simple hazard alerting system that alerts whenever the line-of-sight rate drops below some...

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Hazard alerting using line-of-sight rate

High-fidelity quantum operations on superconducting qubits in the presence of noise

August 15, 2008
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Journal Article
Author:
Andrew J. Kerman
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Published in:
Phys. Rev. Lett., Vol. 101, No. 7, 15 August 2008, 070501.
Topic:
quantum
R&D area:
R&D group:

Summary

We present a scheme for implementing quantum operations with superconducting qubits. Our approach "coupler" qubit to mediate a controllable interaction between data qubits, pulse sequences which strongly mitigate the effects of 1/f flux noise, and a high-Q resonator-based local memory. We develop a Monte Carlo simulation technique capable of describing arbitrary noise-induced dephasing and decay, and demonstrate in this system a set of universal gate operations with O(10^-5) error probabilities in the presence of experimentally measured levels of 1=f noise. We then add relaxation and quantify the decay times required to maintain this error level.
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Summary

We present a scheme for implementing quantum operations with superconducting qubits. Our approach "coupler" qubit to mediate a controllable interaction between data qubits, pulse sequences which strongly mitigate the effects of 1/f flux noise, and a high-Q resonator-based local memory. We develop a Monte Carlo simulation technique capable of describing...

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High-fidelity quantum operations on superconducting qubits in the presence of noise

Comparing convective weather avoidance models and aircraft-based data

August 4, 2008
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Conference Paper
Author:
Richard A. DeLaura
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Published in:
89th ARAM Special Symp., 4 August 2008.
Topic:
aviation weather
R&D area:
R&D group:

Summary

The Convective Weather Avoidance Model (CWAM), developed in collaboration with NASA, translates convective weather information into a Weather Avoidance Field (WAF), to determine if pilots will route around convective regions. The WAF provides an estimate of the probability of pilot deviation around convective weather in en route airspace as a function of time, horizontal location, and flight altitude [1][2]. The results of the WAF can used to create reroutes around regions of convective weather where pilots are more likely to deviate. If reliable WAF information is provided to the cockpit and ground, pilot decisions may become more predictable, simplifying the task of air traffic control in convective weather. The improvement and validation of CWAM requires inference of pilot intent from flight trajectory data, which is challenging. The process currently involves laborious human review of the results of automated deviation detection algorithms. Both previous CWAM studies and a recent validation study [3] illustrate the difficulties and limitations of attempting to infer pilot intent from flight trajectory data. Furthermore, observed flight tracks may not correctly represent pilot preference. In some instances, pilots may have penetrated airspace that they would rather have avoided or they may have avoided airspace that was easily passable. In order to improve and assess the accuracy of the WAF, it is desirable to compare WAF predictions of pilot intent with direct evidence of the airborne experience during weather encounters in en route airspace, such as normal acceleration. To achieve this, a series of flights using a research aircraft was conducted. In the summer of 2008, four research flights (three on 17 July and one on 14 August) were flown in and around convective activity in the upper Midwestern United States to gather aircraft data that could be correlated to the WAF and other remotely-sensed weather data. The aircraft, a Rockwell Sabreliner Model 50 research aircraft (similar to the Sabreliner Model 40 production model) owned by Rockwell-Collins, flew through and around convective activity while recording on-board accelerations for comparison to the WAF deviation probabilities encountered along the flight trajectory. Aircraft state data, on-board weather radar images, video, photographs and pilot narrative from the cockpit were also collected. This paper briefly describes the CWAM model and WAF. Description of the data collection methodology is then presented. Following that section are descriptions of the flights comparing radar data from the flight deck with ground-based weather radar and the WAF. Visual observations and pilot narrative from the flight deck are also presented. Next, the normal acceleration data from on-board accelerometer data are compared with WAF. Finally, conclusions and suggestions for further study are presented.
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Summary

The Convective Weather Avoidance Model (CWAM), developed in collaboration with NASA, translates convective weather information into a Weather Avoidance Field (WAF), to determine if pilots will route around convective regions. The WAF provides an estimate of the probability of pilot deviation around convective weather in en route airspace as a...

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Comparing convective weather avoidance models and aircraft-based data

Measuring the uncertainty of weather forecasts specific to air traffic management operations

August 4, 2008
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Conference Paper
Author:
Michael P. Matthews
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Published in:
89th ARAM Special Symp., 4 August 2008.
Topic:
aviation weather
R&D area:
R&D group:

Summary

In this paper, we develop a novel way to measure the accuracy of weather forecasts based upon the impact on air traffic flows. This method uses new techniques developed as part of the CWAM that consider the complicated interaction between pilots, air traffic controllers and weather. This technique, known as the blockage model (Martin et al., 2006), differentiates between minor deviations performed by pilots around convective weather and their larger deviations due to fully blocked air routes that require air traffic control interaction. This blockage model is being used by the automated Route Availability Planning Tool (RAPT) to predict route blockage for NYC departures. RAPT integrates the Corridor Integrated Weather Systems (CIWS) deterministic 0-2 hour forecasts of precipitation and echo tops into route specific forecasts of impact on air traffic in the congested east coast corridor. Applying the blockage model to the entire CIWS weather domain as a metric for scoring the performance of the forecast algorithms is shown to be an excellent approach for measuring the adequacy of the forecast in predicting the impact of the convective weather on air traffic operations.
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Summary

In this paper, we develop a novel way to measure the accuracy of weather forecasts based upon the impact on air traffic flows. This method uses new techniques developed as part of the CWAM that consider the complicated interaction between pilots, air traffic controllers and weather. This technique, known as...

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Measuring the uncertainty of weather forecasts specific to air traffic management operations

Epitaxial graphene transistors on SiC substrates

August 1, 2008
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Journal Article
Author:
Jakub T. Kedzierski
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Published in:
IEEE Trans. Electron Devices, Vol. 55, No. 8, August 2008, pp. 2078-2085.
Topic:
microelectronics
R&D area:

Summary

This paper describes the behavior of top-gated transistors fabricated using carbon, specifically epitaxial graphene on SiC, as the active material. Although graphene devices have been built before, in this paper, we provide the first demonstration and systematic evaluation of arrays of a large number of transistors produced using standard microelectronics methods. The graphene devices presented feature high-k dielectric, mobilities up to 5000 cm2/V · s, and Ion/Ioff ratios of up to seven, and are methodically analyzed to provide insight into the substrate properties. Typical of graphene, these micrometer-scale devices have negligible band gaps and, therefore, large leakage currents.
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Summary

This paper describes the behavior of top-gated transistors fabricated using carbon, specifically epitaxial graphene on SiC, as the active material. Although graphene devices have been built before, in this paper, we provide the first demonstration and systematic evaluation of arrays of a large number of transistors produced using standard microelectronics...

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Epitaxial graphene transistors on SiC substrates

CMOS-compatible dual-output silicon modulator for analog signal processing

July 21, 2008
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Journal Article
Author:
Steven Jay Spector
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Published in:
Opt. Express, Vol. 16, No. 15, 21 July 2008, pp. 11027-11031.
Topic:
optics
R&D area:
R&D group:

Summary

A broadband, Mach-Zehnder-interferometer based silicon optical modulator is demonstrated, with an electrical bandwidth of 26 GHz and V[pi]L of 4 V·cm. The design of this modulator does not require epitaxial overgrowth and is therefore simpler to fabricate than previous devices with similar performance.
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Summary

A broadband, Mach-Zehnder-interferometer based silicon optical modulator is demonstrated, with an electrical bandwidth of 26 GHz and V[pi]L of 4 V·cm. The design of this modulator does not require epitaxial overgrowth and is therefore simpler to fabricate than previous devices with similar performance.

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CMOS-compatible dual-output silicon modulator for analog signal processing

Proficiency testing for imaging and audio enhancement: guidelines for evaluation

July 21, 2008
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Conference Paper
Author:
Reva Schwartz
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Published in:
Int. Assoc. of Forensic Sciences, IAFS, 21-26 July 2008.
Topic:
cyber security
R&D area:
R&D group:

Summary

Proficiency tests in the forensic sciences are vital in the accreditation and quality assurance process. Most commercially available proficiency testing is available for examiners in the traditional forensic disciplines, such as latent prints, drug analysis, DNA, questioned documents, etc. Each of these disciplines is identification based. There are other forensic disciplines, however, where the output of the examination is not an identification of a person or substance. Two such disciplines are audio enhancement and video/image enhancement.
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Summary

Proficiency tests in the forensic sciences are vital in the accreditation and quality assurance process. Most commercially available proficiency testing is available for examiners in the traditional forensic disciplines, such as latent prints, drug analysis, DNA, questioned documents, etc. Each of these disciplines is identification based. There are other forensic...

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Proficiency testing for imaging and audio enhancement: guidelines for evaluation

Detecting asteroids with a multi-hypothesis velocity matched filter

July 17, 2008
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Conference Paper
Author:
Brian D. Shucker
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Published in:
ACM 2008, 10th Asteroids, Comets Meteors Mtg., 14-18 July 2008.
Topic:
asteroids
R&D area:
R&D group:

Summary

We present a novel approach to image processing for optical detection of faint asteroids. Traditional methods of asteroid detection require observations in multiple frames taken over a period of time, but are limited by the signal-to-noise ratio in a single frame. Our approach is based on a velocity matched filter (VMF), which combines the signal from multiple frames in order to increase the aggregate SNR for dim objects. By generating a series of hypotheses about the apparent velocities of potential objects, we create a set of highly sensitive velocity-specific filters, the results of which are combined to achieve complete coverage of the search space. Each filter collapses a set of sidereal frames into a single frame through a shifted sum operation, thus aggregating the signal from the entire frameset and increasing SNR for objects matching the hypothesized velocity. We also present additional signal processing steps designed to filter out a variety of noise sources such as stars, spacecraft, and background gradients.
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Summary

We present a novel approach to image processing for optical detection of faint asteroids. Traditional methods of asteroid detection require observations in multiple frames taken over a period of time, but are limited by the signal-to-noise ratio in a single frame. Our approach is based on a velocity matched filter...

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Detecting asteroids with a multi-hypothesis velocity matched filter

PVTOL: providing productivity, performance, and portability to DoD signal processing applications on multicore processors

July 14, 2008
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Conference Paper
Author:
Hahn G. Kim
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Published in:
DoD HPCMP 2008, High Performance Computing Modernization Program Users Group Conf., 14 July 2008, pp. 327-333.
Topic:
high performance computing
R&D area:
R&D group:

Summary

PVTOL provides an object-oriented C++ API that hides the complexity of multicore architectures within a PGAS programming model, improving programmer productivity. Tasks and conduits enable data flow patterns such as pipelining and round-robining. Hierarchical maps concisely describe how to allocate hierarchical arrays across processor and memory hierarchies and provide a simple API for moving data across these hierarchies. Functors encapsulate computational kernels; new functors can be easily developed using the PVTOL API and can be fused for more efficient computation. Existing computation and communication technologies that are optimized for various architectures are used to achieve high performance. PVTOL abstracts the details of the underlying processor architectures to provide portability. We are actively developing PVTOL for Intel, PowerPC and Cell architectures and intend to add support for more computational kernels on these architectures. FPGAs are becoming popular for accelerating computation in both the high performance computing (HPC) and high performance embedded computing (HPEC) communities. Integrated processor-FPGA technologies are now available from both HPC and HPEC vendors, e.g. Cray and Mercury Computer Systems. We plan to support FPGAs as co-processors in PVTOL. Finally, automated mapping technology has been demonstrated with pMatlab. We plan to begin implementing automated mapping in PVTOL next year. Similar to PVL, as PVTOL matures and is used in more projects at Lincoln, we plan to propose concepts demonstrated in PVTOL to HPEC-SI for adoption into future versions of VSIPL++.
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Summary

PVTOL provides an object-oriented C++ API that hides the complexity of multicore architectures within a PGAS programming model, improving programmer productivity. Tasks and conduits enable data flow patterns such as pipelining and round-robining. Hierarchical maps concisely describe how to allocate hierarchical arrays across processor and memory hierarchies and provide a...

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PVTOL: providing productivity, performance, and portability to DoD signal processing applications on multicore processors

Higher order cochlea-like channelizing filters

July 1, 2008
  |
Journal Article
Author:
Christopher J. Galbraith
…
Published in:
IEEE Trans. Microw. Theory Tech., Vol. 56, No. 7, July 2008, pp. 1675-1683.
Topic:
wireless
R&D area:
R&D group:

Summary

A design method is presented for contiguous-channel multiplexing filters with many channels covering a wide bandwidth. The circuit topology extends previous work on cochlea-like channelizers by introducing multiple resonator-channel filter sections. The new design provides increased stopband rejection, lower insertion loss, and improved passband shape compared with the earlier version while retaining a simple design method and a compact layout, and requires no post-fabrication tuning. Results of a three-pole ten-channel channelizer covering from 182 MHz to 1.13 GHz with 17.5% bandwidth channels and 1.1-dB insertion loss are presented, and agree well with theory. A discussion of the power handling of planar channelizers is also presented.
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Summary

A design method is presented for contiguous-channel multiplexing filters with many channels covering a wide bandwidth. The circuit topology extends previous work on cochlea-like channelizers by introducing multiple resonator-channel filter sections. The new design provides increased stopband rejection, lower insertion loss, and improved passband shape compared with the earlier version...

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Higher order cochlea-like channelizing filters
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