Publications
Design and development of the TFDM information management architecture
April 30, 2009
Conference Paper
Published in:
Integrated Communication, Navigation and Surveillance Conf., ICNS, 13-15 May 2009.
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Summary
The Tower Flight Data Manager (TFDM) is a new terminal automation platform that will provide an integrated tower-user display suite including an extended electronic flight strip or "flight data management" (FDM) display. The integrated information exchange and processing environment established by TFDM will support a suite of automation-assisted user support tools collectively designated as the Arrival/Departure Management Tool or A/DMT. A/DMT will develop and manage an integrated plan for arrival, scheduled (and to the extent possible) non-scheduled departure operations at the airport, based on 4D-trajectory assignments. A primary concern of A/DMT is the efficient use of the runway complex to meet service demand from both arrivals and departures. In addition, A/DMT seeks to reduce fuel usage and engine emissions on the airport surface, to permit more efficient use of gates and holding areas, and to enhance the safety of surface operations. We first put forth a strategy for developing a scalable TFDM-A/DMT Information Management Architecture (TIMA) employing standard information exchange models, services and data formats. This architecture will be consistent with evolving System Wide Information Management (SWIM) technologies and data standards, and will support efficient insertion of processing algorithms (e.g. surface trajectory management algorithms) developed by the research community and/or industry. Next, we describe TIMA . While TIMA makes use of Service-Oriented Architecture (SOA) principles, it is primarily an information-oriented architecture; we discuss why this architectural style is necessary for TFDM, and how it is also beneficial for SWIM. We conclude with a description of a general model for managing temporal aspects of information within TFDM. TIMA needs to support not only real-time operations, but post-facto analysis as well. A major difficulty in conducting analyses involving different data sources is time synchronization of data. We describe a method for associating temporal information with data sources in a data-agnostic manner, so that data can be retrieved from a variety of sources in a uniform manner.
Summary
The Tower Flight Data Manager (TFDM) is a new terminal automation platform that will provide an integrated tower-user display suite including an extended electronic flight strip or "flight data management" (FDM) display. The integrated information exchange and processing environment established by TFDM will support a suite of automation-assisted user support...
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Evaluation of TCAS II Version 7.1 using the FAA Fast-Time Encounter Generator model [volume 1]
April 29, 2009
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-346,I
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This report documents the Lincoln Laboratory evaluation of the Traffic Alert and Collision Avoidance System II (TCAS II) logic version 7.1. TCAS II is an airborne collision avoidance system required since 30 December 1993 by the FAA on all air carrier aircraft with more than 30 passenger seats operating in the U.S. airspace. Version 7.1 was created to correct two potential safety problems in earlier versions. The first change focuses on the sense reversal logic. The second change focuses on avoiding "wrong way" responses to Vertical Speed Limit or "Adjust Vertical Speed, Adjust" RAs. Lincoln Laboratory evaluated the logic by examining more than eight million simulated pairwise encounters, derived from actual tracks recorded in U.S. airspace. The main goals of the evaluation were: (1) to study the performance of the revised sense reversal logic for encounters where one pilot ignores the TCAS advisory; (2) to determine if the revised sense reversal logic has an adverse impact on encounters where both pilots follow the TCAS advisories; (3) to determine if the change from "Adjust Vertical Speed, Adjust" advisories to "Level Off, Level Off" advisories provides a safety benefit for TCAS. Three sets of encounters were examined in order to fulfill these goals: encounters where both aircraft are TCAS-equipped and both pilots follow the advisories; encounters where both aircraft are TCAS-equipped and one pilot does not follow the advisory; and encounters where only one aircraft is TCAS-equipped. A detailed analysis followed by a summary is provided for each set of encounters. An overall summary is given at the end of the report.
Summary
This report documents the Lincoln Laboratory evaluation of the Traffic Alert and Collision Avoidance System II (TCAS II) logic version 7.1. TCAS II is an airborne collision avoidance system required since 30 December 1993 by the FAA on all air carrier aircraft with more than 30 passenger seats operating in...
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Evaluation of TCAS II Version 7.1 using the FAA Fast-Time Encounter Generator model : appendix [volume 2]
April 29, 2009
Project Report
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MIT Lincoln Laboratory Report ATC-346,II
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Appendix to Project Report ATC-346, Evaluation of TCAS II Version 7.1 Using the Fast-Time Encounter Generator Model, Volume 1.
Summary
Appendix to Project Report ATC-346, Evaluation of TCAS II Version 7.1 Using the Fast-Time Encounter Generator Model, Volume 1.
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Encounter models for unconventional aircraft version 1.0
April 10, 2009
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-348
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Airspace encounter models, covering close encounter situations that may occur after standard separation assurance has been lost, are a critical component in the safety assessment of aviation procedures and collision avoidance systems. Of particular relevance to Unmanned Aircraft Systems (UAS) is the potential for encountering general aviation aircraft that are flying under Visual Flight Rules (VFR) and are not in contact with air traffic control. In response to the need to develop a model of these types of encounters, Lincoln Laboratory undertook an extensive data collection and modeling effort involving more than 96,000 unconventional aircraft tracks. The outcome of this effort was nine individual models encompassing ultralights, gliders, balloons, and airships. The models use Bayesian networks to represent relationships between dynamic variables and to construct random trajectories that are statistically similar to those observed in the data. The intruder trajectories can be used in fast-time Monte Carlo simulations to estimate collision risk. The model described in this report is one of three developed by Lincoln Laboratory. A correlated encounter model has been developed to represent situations in which it is likely that there would b e air traffic control intervention prior to a close enounter. The correlated model applies to encounters involving aircraft receiving Air Traffic Control (ATC) services and with transponders. TAn encounter with an intruder that does not have a transponder is uncorrelated in the sense that it is unlikely that there would be prior intervention by air traffic control. The uncorrelated model described in this report is based on global databases of pilot-submitted track data. This work is a follow-on to an uncorrelated conventional model developed from recorded radar tracks from aircraft using a 1200 transponder code. A byproduct of this encounter modeling effort was the extraction of feature distributions for unconventional aircraft. This provides an extensive collection of unconventional aircraft behavior in the airspace.
Summary
Airspace encounter models, covering close encounter situations that may occur after standard separation assurance has been lost, are a critical component in the safety assessment of aviation procedures and collision avoidance systems. Of particular relevance to Unmanned Aircraft Systems (UAS) is the potential for encountering general aviation aircraft that are...
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Airspace encounter models for conventional and unconventional aircraft
March 25, 2009
Conference Paper
Published in:
8th USA/Europe Air Traffic Management Research and Development Sem. (ATM 2009), 25 March 2009.
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Collision avoidance systems play an important role in the future of aviation safety. Before new technologies on board manned or unmanned aircraft are deployed, rigorous analysis using encounter simulations is required to prove system robustness. These simulations rely on models that accurately reflect the geometries and dynamics of aircraft encounters at close range. These types of encounter models have been developed by several organizations since the early 1980s. Lincoln Laboratory's newer encounter models, however, provide a higher-fidelity representation of encounters, are based on substantially more data, leverage a theoretical framework for finding optimal model structures, and reflect recent changes in the airspace. Three categories of encounter model were developed by Lincoln Laboratory. Two of these categories are used for modeling conventional aircraft; one involving encounters with prior air traffic control intervention and one without. The third category of encounter model is for encounters with unconventional aircraft -- such as gliders, skydivers, balloons, and airships -- that typically do not carry transponders. Together, these encounter models are being used to examine the safety and effectiveness of aircraft collision avoidance systems and as a foundation for algorithms for future manned and unmanned systems.
Summary
Collision avoidance systems play an important role in the future of aviation safety. Before new technologies on board manned or unmanned aircraft are deployed, rigorous analysis using encounter simulations is required to prove system robustness. These simulations rely on models that accurately reflect the geometries and dynamics of aircraft encounters...
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Dry cyclogenesis and dust mobilization in the intertropical discontinuity of the West African Monsoon: a case study
March 14, 2009
Journal Article
Published in:
J. Geophys. Res., Vol. 114, 14 March 2009, D05115.
Summary
Three-dimensional mesoscale numerical simulations were performed over Niger in order to investigate dry cyclogenesis in the West African intertropical discontinuity (ITD) during the summer, when it is located over the Sahel. The implications of dry cyclogenesis on dust emission and transport over West Africa are also addressed using the model results, together with spaceborne observations from the Spinning Enhanced Visible and Infra-Red Imager (SEVIRI) and the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP). The study focuses on the case of 7-8 July 2006, during the African Monsoon Multidisciplinary Analysis (AMMA) Special Observing Period 2a1. Model results show the formation of three dry cyclones in the ITD during a 24-h period. Simulations are used to investigate the formation and the development of one of these cyclones over Niger in the lee of the Hoggar-Air Mountains. They show the development of the vortex to be associated with (1) strong horizontal shear and low-level convergence existing along the monsoon shearline and (2) enhanced northeasterly winds associated with orographic blocking of air masses from the Mediterranean Sea. The dry cyclone was apparent between 0700 and 1300 UTC in the simulation, and it was approximately 400 km wide and 1500 m deep. Potential vorticity in the center of vortex reached nearly 6 PVU at the end of the cyclogenesis period (1000 UTC). The role of the orography on cyclogenesis along the ITD was evaluated through model simulations without orography. The comparison of the characteristics of the vortex in the simulations with and without orography suggests that the orography plays a secondary but still important role in the formation of the cyclone. Orography and related flow splitting tend to create low-level jets in the lee of the Hoggar and Air mountains which, in turn, create conditions favorable for the onset of a better defined and more intense vortex in the ITD region. Moreover, orography blocking appears to favor the occurrence of a longer-lived cyclone. Furthermore, model results suggested that strong surface winds (~11 m s−1) enhanced by the intensification of the vortex led to the emission of dust mass fluxes as large as 3 ug m−2 s−1. The mobilized dust was mixed upward to a height of 4–5 km to be made available for long-range transport. This study suggests that the occurrence of dry vortices in the ITD region may contribute significantly to the total dust activity over West Africa during summer. The distribution of dust over the Sahara-Sahel may be affected over areas and at time scales much larger than those associated with the cyclone itself.
Summary
Three-dimensional mesoscale numerical simulations were performed over Niger in order to investigate dry cyclogenesis in the West African intertropical discontinuity (ITD) during the summer, when it is located over the Sahel. The implications of dry cyclogenesis on dust emission and transport over West Africa are also addressed using the model...
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Ultra-wideband offset bicone/dipole antenna: simulations and measurements
March 8, 2009
Conference Paper
Published in:
Ann. Rev. of Progress in Applied Computational Electromagnetics, 8-12 March 2009.
Summary
An ultrawideband (UWB) antenna has been developed for operation in the 60 MHz to 18 GHz frequency range. This antenna is a new type--an offset bicone/dipole design that allows for vertically polarized omnidirectional coverage over an instantaneous 300:1 bandwidth. Numerical electromagnetic simulations with the finite-element method (FEM) were used to investigate the antenna concept and optimize geometry prior to fabrication. Measurements both outdoors and in an anechoic chamber confirm the antenna's performance.
Summary
An ultrawideband (UWB) antenna has been developed for operation in the 60 MHz to 18 GHz frequency range. This antenna is a new type--an offset bicone/dipole design that allows for vertically polarized omnidirectional coverage over an instantaneous 300:1 bandwidth. Numerical electromagnetic simulations with the finite-element method (FEM) were used to...
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Modeling and detection techniques for counter-terror social network analysis and intent recognition
March 7, 2009
Conference Paper
Published in:
2009 IEEE Aerospace Conf., March 7-14 2009.
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In this paper, we describe our approach and initial results on modeling, detection, and tracking of terrorist groups and their intents based on multimedia data. While research on automated information extraction from multimedia data has yielded significant progress in areas such as the extraction of entities, links, and events, less progress has been made in the development of automated tools for analyzing the results of information extraction to ?connect the dots.? Hence, our Counter-Terror Social Network Analysis and Intent Recognition (CT-SNAIR) work focuses on development of automated techniques and tools for detection and tracking of dynamically-changing terrorist networks as well as recognition of capability and potential intent. In addition to obtaining and working with real data for algorithm development and test, we have a major focus on modeling and simulation of terrorist attacks based on real information about past attacks. We describe the development and application of a new Terror Attack Description Language (TADL), which is used as a basis for modeling and simulation of terrorist attacks. Examples are shown which illustrate the use of TADL and a companion simulator based on a Hidden Markov Model (HMM) structure to generate transactions for attack scenarios drawn from real events. We also describe our techniques for generating realistic background clutter traffic to enable experiments to estimate performance in the presence of a mix of data. An important part of our effort is to produce scenarios and corpora for use in our own research, which can be shared with a community of researchers in this area. We describe our scenario and corpus development, including specific examples from the September 2004 bombing of the Australian embassy in Jakarta and a fictitious scenario which was developed in a prior project for research in social network analysis. The scenarios can be created by subject matter experts using a graphical editing tool. Given a set of time ordered transactions between actors, we employ social network analysis (SNA) algorithms as a filtering step to divide the actors into distinct communities before determining intent. This helps reduce clutter and enhances the ability to determine activities within a specific group. For modeling and simulation purposes, we generate random networks with structures and properties similar to real-world social networks. Modeling of background traffic is an important step in generating classifiers that can separate harmless activities from suspicious activity. An algorithm for recognition of simulated potential attack scenarios in clutter based on Support Vector Machine (SVM) techniques is presented. We show performance examples, including probability of detection versus probability of false alarm tradeoffs, for a range of system parameters.
Summary
In this paper, we describe our approach and initial results on modeling, detection, and tracking of terrorist groups and their intents based on multimedia data. While research on automated information extraction from multimedia data has yielded significant progress in areas such as the extraction of entities, links, and events, less...
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Forensic speaker recognition: a need for caution
March 1, 2009
Journal Article
Published in:
IEEE Signal Process. Mag., Vol. 26, No. 2, March 2009, pp. 95-103.
Summary
There has long been a desire to be able to identify a person on the basis of his or her voice. For many years, judges, lawyers, detectives, and law enforcement agencies have wanted to use forensic voice authentication to investigate a suspect or to confirm a judgment of guilt or innocence. Challenges, realities, and cautions regarding the use of speaker recognition applied to forensic-quality samples are presented.
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There has long been a desire to be able to identify a person on the basis of his or her voice. For many years, judges, lawyers, detectives, and law enforcement agencies have wanted to use forensic voice authentication to investigate a suspect or to confirm a judgment of guilt or...
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A 4-side tileable back illuminated 3D-integrated Mpixel CMOS image sensor
February 9, 2009
Conference Paper
Published in:
ISSCC 09, 2009 IEEE Int. Solid-State Circuits Conf., 8-12 February 2009, pp. 38-39.
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The dominant trend with conventional image sensors is toward scaled-down pixel sizes to increase spatial resolution and decrease chip size and cost. While highly capable chips, these monolithic image sensors devote substantial perimeter area to signal acquisition and control circuitry and trade off pixel complexity for fill factor. For applications such as wide-area persistent surveillance, reconnaissance, and astronomical sky surveys it is desirable to have simultaneous near-real-time imagery with fast, wide field-of-view coverage. Since the fabrication of a complex large-format sensor on a single piece of silicon is cost and yield-prohibitive and is limited to the wafer size, for these applications many smaller-sized image sensors are tiled together to realize very large arrays. Ideally the tiled image sensor has no missing pixels and the pixel pitch is continuous across the seam to minimize loss of information content. CCD-based imagers have been favored for these large mosaic arrays because of their low noise and high sensitivity, but CMOS-based image sensors bring architectural benefits, including electronic shutters, enhanced radiation tolerance, and higher data-rate digital outputs that are more easily scalable to larger arrays. In this report the first back-illuminated, 1 Mpixel, 3D-integrated CMOS image sensor with 8 mum-pitch 3D via connections. The chip employs a conventional pixel layout and requires 500 mum of perimeter silicon to house the support circuitry and protect the array from saw damage. In this paper we present a back-illuminated 1 Mpixel CMOS image sensor tile that includes a 64-channel vertically integrated ADC chip stack, and requires only a few pixels of silicon perimeter to the pixel array. The tile and system connector design support 4-side abuttability and fast burst data rates.
Summary
The dominant trend with conventional image sensors is toward scaled-down pixel sizes to increase spatial resolution and decrease chip size and cost. While highly capable chips, these monolithic image sensors devote substantial perimeter area to signal acquisition and control circuitry and trade off pixel complexity for fill factor. For applications...
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