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Benefits assessment methodology for an air traffic control tower advanced automation system

Published in:
ATIO 2010: 10th AIAA Aviation Technology Integration and Operations Conf., 13-15 September 2010.

Summary

This paper presents a benefits assessment methodology for an air traffic control tower advanced automation system called the Tower Flight Data Manager (TFDM), which is being considered for development by the FAA to support NextGen operations. The standard FAA benefits analysis methodology is described, together with how it has been tailored to the TFDM application to help inform the development process and the business case for system deployment. Parts of the methodology are illustrated through data analysis and modeling, and insights are presented to help prioritize TFDM capability development.
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Summary

This paper presents a benefits assessment methodology for an air traffic control tower advanced automation system called the Tower Flight Data Manager (TFDM), which is being considered for development by the FAA to support NextGen operations. The standard FAA benefits analysis methodology is described, together with how it has been...

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On estimating mid-air collision risk

Published in:
ATIO 2010: 10th AIAA Aviation Technology Integration and Operations Conf., 13-15 September 2010.

Summary

Many aviation safety studies involve estimating near mid-air collision (NMAC) rate. In the past, it has been assumed that the probability that an NMAC leads to a mid-air collision is 0.1, but there has not yet been a comprehensive study to serve as a basis for this estimate. This paper explains how to use existing encounter models, a flight simulation framework, three-dimensional aircraft wireframe models, and surveillance data to estimate mid-air collision risk. The results show that 0.1 is an overly conservative estimate and that the true rate is likely to be an order of magnitude lower.
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Summary

Many aviation safety studies involve estimating near mid-air collision (NMAC) rate. In the past, it has been assumed that the probability that an NMAC leads to a mid-air collision is 0.1, but there has not yet been a comprehensive study to serve as a basis for this estimate. This paper...

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Machine learning in adversarial environments

Published in:
Mach. Learn., Vol. 81, No. 2, November 2010, pp. 115-119.

Summary

Whenever machine learning is used to prevent illegal or unsanctioned activity and there is an economic incentive, adversaries will attempt to circumvent the protection provided. Constraints on how adversaries can manipulate training and test data for classifiers used to detect suspicious behavior make problems in this area tractable and interesting. This special issue highlights papers that span many disciplines including email spam detection, computer intrusion detection, and detection of web pages deliberately designed to manipulate the priorities of pages returned by modern search engines. The four papers in this special issue provide a standard taxonomy of the types of attacks that can be expected in an adversarial framework, demonstrate how to design classifiers that are robust to deleted or corrupted features, demonstrate the ability of modern polymorphic engines to rewrite malware so it evades detection by current intrusion detection and antivirus systems, and provide approaches to detect web pages designed to manipulate web page scores returned by search engines. We hope that these papers and this special issue encourages the multidisciplinary cooperation required to address many interesting problems in this relatively new area including predicting the future of the arms races created by adversarial learning, developing effective long-term defensive strategies, and creating algorithms that can process the massive amounts of training and test data available for internet-scale problems.
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Summary

Whenever machine learning is used to prevent illegal or unsanctioned activity and there is an economic incentive, adversaries will attempt to circumvent the protection provided. Constraints on how adversaries can manipulate training and test data for classifiers used to detect suspicious behavior make problems in this area tractable and interesting...

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Traffic Management Advisor (TMA) weather integration

Published in:
MIT Lincoln Laboratory Report ATC-364

Summary

TCAS behavior in New England airspace is being monitored and analyzed, making use of an omni-directional 1030/1090 MHz receiver. The receiver system, located in Lexington, MA, and operated by M.I.T. Lincoln Laboratory, is used to record Resolution Advisories (RAs). Omni-directional receptions make it possible to examine the air-to-air messages exchanged between aircraft for coordination of RAs. Omni-directional reception rates are also being studied. THe results indicated the percentage of aircraft that are TCAS equipped and the percentage of received signals that originate from TCAS and other systems. A third aspect of the program evaluates the availablity of 1090 MHz Extended Squitter data for use in collision avoidance systems. Data is recorded continuously, and the busiest periods are selected for focused attention.
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Summary

TCAS behavior in New England airspace is being monitored and analyzed, making use of an omni-directional 1030/1090 MHz receiver. The receiver system, located in Lexington, MA, and operated by M.I.T. Lincoln Laboratory, is used to record Resolution Advisories (RAs). Omni-directional receptions make it possible to examine the air-to-air messages exchanged...

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Collision avoidance for unmanned aircraft using Markov Decision Processes

Summary

Before unmanned aircraft can fly safely in civil airspace, robust airborne collision avoidance systems must be developed. Instead of hand-crafting a collision avoidance algorithm for every combination of sensor and aircraft configuration, we investigate the automatic generation of collision avoidance algorithms given models of aircraft dynamics, sensor performance, and intruder behavior. By formulating the problem of collision avoidance as a Markov Decision Process (MDP) for sensors that provide precise localization of the intruder aircraft, or a Partially Observable Markov Decision Process (POMDP) for sensors that have positional uncertainty or limited field-of-view constraints, generic MDP/POMDP solvers can be used to generate avoidance strategies that optimize a cost function that balances flight-plan deviation with collision. Experimental results demonstrate the suitability of such an approach using four different sensor modalities and a parametric aircraft performance model.
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Summary

Before unmanned aircraft can fly safely in civil airspace, robust airborne collision avoidance systems must be developed. Instead of hand-crafting a collision avoidance algorithm for every combination of sensor and aircraft configuration, we investigate the automatic generation of collision avoidance algorithms given models of aircraft dynamics, sensor performance, and intruder...

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Wind-shear system cost-benefit analysis

Author:
Published in:
Lincoln Laboratory Journal, Vol. 18, No. 2, August 20, pp. 47-68.

Summary

Mitigating thunderstorm wind-shear threats for aircraft near the ground has been an important issue since the 1970s, when several fatal commercial aviation accidents were attributed to wind shear. Updating the knowledge base for airport wind-shear exposure and effectiveness of detection systems has become critical to the Federal Aviation Administration as they consider options for aging systems and evaluations of new systems.
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Summary

Mitigating thunderstorm wind-shear threats for aircraft near the ground has been an important issue since the 1970s, when several fatal commercial aviation accidents were attributed to wind shear. Updating the knowledge base for airport wind-shear exposure and effectiveness of detection systems has become critical to the Federal Aviation Administration as...

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GROK: a practical system for securing group communications

Published in:
NCA 2010, 9th IEEE Int. Symp. on Network Computing and Applications, 15 July 2010, pp. 100-107.

Summary

We have designed and implemented a general-purpose cryptographic building block, called GROK, for securing communication among groups of entities in networks composed of high-latency, low-bandwidth, intermittently connected links. During the process, we solved a number of non-trivial system problems. This paper describes these problems and our solutions, and motivates and justifies these solutions from three viewpoints: usability, efficiency, and security. The solutions described in this paper have been tempered by securing a widely-used group-oriented application, group text chat. We implemented a prototype extension to a popular text chat client called Pidgin and evaluated it in a real-world scenario. Based on our experiences, these solutions are useful to designers of group-oriented systems specifically, and secure systems in general.
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Summary

We have designed and implemented a general-purpose cryptographic building block, called GROK, for securing communication among groups of entities in networks composed of high-latency, low-bandwidth, intermittently connected links. During the process, we solved a number of non-trivial system problems. This paper describes these problems and our solutions, and motivates and...

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Predictive modeling of forecast uncertainty in the Route Availability Planning Tool (RAPT)

Published in:
2010 Intl. Conf. on Scientific Computing, CSC, 12-15 July 2010.

Summary

MIT Lincoln Laboratory has developed the Route Availability Planning Tool (RAPT), which provides automated convective weather guidance to air traffic managers of the NYC metro region. Prior studies of RAPT have shown high-accuracy guidance from forecast weather, but further refinements to prevent forecast misclassification is still desirable. An attribute set of highly correlated predictors for forecast misclassification is identified. Using this attribute set, a variety of prediction models for forecast misclassification are generated and evaluated. Rule-based models, decision trees, multi-layer perceptrons, and Bayesian prediction model techniques are used. Filtering, resampling, and attribute selection methods are applied to refine model generation. Our results show promising accuracy rates for multi-layer perceptrons trained on full attribute sets.
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Summary

MIT Lincoln Laboratory has developed the Route Availability Planning Tool (RAPT), which provides automated convective weather guidance to air traffic managers of the NYC metro region. Prior studies of RAPT have shown high-accuracy guidance from forecast weather, but further refinements to prevent forecast misclassification is still desirable. An attribute set...

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Weighted nuisance attribute projection

Published in:
Odyssey 2010, the Speaker and Language Recognition Workshop, 28 June - 1 July 2010.

Summary

Nuisance attribute projection (NAP) has become a common method for compensation of channel effects, session variation, speaker variation, and general mismatch in speaker recognition. NAP uses an orthogonal projection to remove a nuisance subspace from a larger expansion space that contains the speaker information. Training the NAP subspace is based on optimizing pairwise distances to reduce intraspeaker variability and retain interspeaker variability. In this paper, we introduce a novel form of NAP called weighted NAP (WNAP) which significantly extends the current methodology. For WNAP, we propose a training criterion that incorporates two critical extensions to NAP variable metrics and instance-weighted training. Both an eigenvector and iterative method are proposed for solving the resulting optimization problem. The effectiveness of WNAP is shown on a NIST speaker recognition evaluation task where error rates are reduced by over 20%.
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Summary

Nuisance attribute projection (NAP) has become a common method for compensation of channel effects, session variation, speaker variation, and general mismatch in speaker recognition. NAP uses an orthogonal projection to remove a nuisance subspace from a larger expansion space that contains the speaker information. Training the NAP subspace is based...

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Adaptive optics wavefront sensors based on photon-counting detector arrays

Published in:
Proc. SPIE Vol. 7736, Adaptive Optics Systems II, 27 June 2010, 773610.

Summary

For adaptive optics systems, there is a growing demand for wavefront sensors that operate at higher frame rates and with more pixels while maintaining low readout noise. Lincoln Laboratory has been investigating Geiger·mode avalanche photodiode arrays integrated with CMOS readout circuits as a potential solution. This type of sensor counts photons digitally within the pixel, enabling data to be read out at high rates without the penalty of readout noise. After a brief overview of adaptive optics sensor development at Lincoln Laboratory, we will present the status of silicon Geiger· mode·APD technology along with future plans to improve performance.
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Summary

For adaptive optics systems, there is a growing demand for wavefront sensors that operate at higher frame rates and with more pixels while maintaining low readout noise. Lincoln Laboratory has been investigating Geiger·mode avalanche photodiode arrays integrated with CMOS readout circuits as a potential solution. This type of sensor counts...

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