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Convection diagnosis and nowcasting for oceanic aviation applications

August 25, 2008
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Conference Paper
Author:
Cathy J. Kessinger
…
Published in:
Proc. SPIE, Vol. 7088, Remote Sensing Applications for Aviation Weather Hazard Detection and Decision Support, 25 August 2008, 708808.
Topic:
aviation weather
R&D area:
R&D group:

Summary

An oceanic convection diagnosis and nowcasting system is described whose domain of interest is the region between the southern continental United States and the northern extent of South America. In this system, geostationary satellite imagery are used to define the locations of deep convective clouds through the weighted combination of three independent algorithms. The resultant output, called the Convective Diagnosis Oceanic (CDO) product, is independently validated against space-borne radar and lightning products from the Tropical Rainfall Measuring Mission (TRMM) satellite to ascertain the ability of the CDO to discriminate hazardous convection. The CDO performed well in this preliminary investigation with some limitations noted. Short-term, 1-hr and 2-hr nowcasts of convection location are performed within the Convective Nowcasting Oceanic (CNO) system using a storm tracker. The CNO was found to have good statistical performance at extrapolating existing storm positions. Current work includes the development and implementation of additional atmospheric features for nowcasting convection initiation and to improve nowcasting of mature convection evolution.
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Summary

An oceanic convection diagnosis and nowcasting system is described whose domain of interest is the region between the southern continental United States and the northern extent of South America. In this system, geostationary satellite imagery are used to define the locations of deep convective clouds through the weighted combination of...

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Convection diagnosis and nowcasting for oceanic aviation applications

A Bayesian approach to aircraft encounter modeling

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

Aircraft encounter models can be used in a variety of analyses, including collision avoidance system safety assessment, sensor design trade studies, and visual acquisition analysis. This paper presents an approach to airspace encounter model construction based on Markov models estimated from radar data. We use Bayesian networks to represent the distribution over initial states and dynamic Bayesian networks to represent transition probabilities. We apply Bayesian statistical techniques to identify the relationships between the variables in the model to best leverage a large volume of raw aircraft track data obtained from more than 130 radars across the United States.
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Summary

Aircraft encounter models can be used in a variety of analyses, including collision avoidance system safety assessment, sensor design trade studies, and visual acquisition analysis. This paper presents an approach to airspace encounter model construction based on Markov models estimated from radar data. We use Bayesian networks to represent the...

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A Bayesian approach to aircraft encounter modeling

Applications of a macroscopic model for en route sector capacity

August 18, 2008
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Conference Paper
Author:
Jerry D. Welch
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Published in:
AIAA Guidance, Navigation and Control Conf. and Exhibit, 18-21 August 2008.
Topic:
air traffic control
R&D area:
R&D group:

Summary

Airspace capacity estimates are important both for airspace design and for operational air traffic management. Considerable effort has gone into understanding the complexity factors that reduce sector capacity by increasing controller workload. Yet no analytical means is available for accurately estimating the maximum capacity of an en route sector. The Monitor Alert Parameter (MAP) values that determine the operational traffic limit of en route sectors in the United States account only for workload from inter-sector coordination tasks. We propose a more complete sector capacity model that also accounts for workload from conflict avoidance and recurring tasks. We use mean closing speeds and airspace separation standards to estimate aircraft conflict rates. We estimate the mean controller service times for all three task types by fitting the model against observed peak traffic counts for hundreds of en route airspace volumes in the Northeastern United States. This macroscopic approach provides numerical capacity predictions that closely bound peak observed traffic densities for those airspace volumes. This paper reviews recent efforts to improve the accuracy of the bound by replacing certain global parameters with measured data from individual sectors. It also compares the model capacity with MAP values for sectors in the New York Center. It concludes by illustrating the use of the model to predict the capacity benefits of proposed technological and operational improvements to the air traffic management system.
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Summary

Airspace capacity estimates are important both for airspace design and for operational air traffic management. Considerable effort has gone into understanding the complexity factors that reduce sector capacity by increasing controller workload. Yet no analytical means is available for accurately estimating the maximum capacity of an en route sector. The...

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Applications of a macroscopic model for en route sector capacity

Electro-optical system analysis for sense and avoid

August 18, 2008
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Conference Paper
Author:
John Daniel Griffith
…
Published in:
AIAA Guidance, Navigation, and Control Conf. and Exhibit, 19-21 August 2008.
Topic:
collision avoidance
R&D area:
R&D group:

Summary

This paper presents a parametric analysis of the sense and avoid capability for an electro- optical system on unmanned aircraft. Our sensor analysis is based on simulated encounters from a new U.S. airspace encounter model that provides a comprehensive distribution of typical visual flight rule (VFR) aircraft behavior and encounter geometries. We assess the exchange between the sensor field-of-view shape and detection range with the probability of intruder detection prior to near miss. This assessment also includes a trade-off analysis between field-of-view azimuth angle and probability of detection with fixed tracking technology (i.e. pixel array sensor and tracking algorithm). Initial results suggest that current standards are suitable for detecting larger aircraft but may not be ideal for small aircraft such as ultralights.
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Summary

This paper presents a parametric analysis of the sense and avoid capability for an electro- optical system on unmanned aircraft. Our sensor analysis is based on simulated encounters from a new U.S. airspace encounter model that provides a comprehensive distribution of typical visual flight rule (VFR) aircraft behavior and encounter...

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Electro-optical system analysis for sense and avoid

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
…
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
…
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
…
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

Proficiency testing for imaging and audio enhancement: guidelines for evaluation

July 21, 2008
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Conference Paper
Author:
Reva Schwartz
…
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
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