Publications
The MMSR bilingual and crosschannel corpora for speaker recognition research and evaluation
May 31, 2004
Conference Paper
Published in:
ODYSSEY 2004, Speaker and Language Recognition Workshop, 31 May - 3 June 2004.
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Summary
We describe efforts to create corpora to support and evaluate systems that meet the challenge of speaker recognition in the face of both channel and language variation. In addition to addressing ongoing evaluation of speaker recognition systems, these corpora are aimed at the bilingual and crosschannel dimensions. We report on specific data collection efforts at the Linguistic Data Consortium, the 2004 speaker recognition evaluation program organized by the National Institute of Standards and Technology (NIST), and the research ongoing at the US Federal Bureau of Investigation and MIT Lincoln Laboratory. We cover the design and requirements, the collections and evaluation integrating discussions of the data preparation, research, technology development and evaluation on a grand scale.
Summary
We describe efforts to create corpora to support and evaluate systems that meet the challenge of speaker recognition in the face of both channel and language variation. In addition to addressing ongoing evaluation of speaker recognition systems, these corpora are aimed at the bilingual and crosschannel dimensions. We report on...
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Conversational telephone speech corpus collection for the NIST speaker recognition evaluation 2004
May 24, 2004
Conference Paper
Published in:
Proc. Language Resource Evaluation Conf., LREC, 24-30 May 2004, pp. 587-590.
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Summary
This paper discusses some of the factors that should be considered when designing a speech corpus collection to be used for text independent speaker recognition evaluation. The factors include telephone handset type, telephone transmission type, language, and (non-telephone) microphone type. The paper describes the design of the new corpus collection being undertaken by the Linguistic Data Consortium (LDC) to support the 2004 and subsequent NIST speech recognition evaluations. Some preliminary information on the resulting 2004 evaluation test set is offered.
Summary
This paper discusses some of the factors that should be considered when designing a speech corpus collection to be used for text independent speaker recognition evaluation. The factors include telephone handset type, telephone transmission type, language, and (non-telephone) microphone type. The paper describes the design of the new corpus collection...
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The mixer corpus of multilingual, multichannel speaker recognition data
May 24, 2004
Conference Paper
Published in:
Proc. Language Resource Evaluation Conf., LREC, 24-30 May 2004, pp. 627-630.
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Summary
This paper describes efforts to create corpora to support and evaluate systems that perform speaker recognition where channel and language may vary. Beyond the ongoing evaluation of speaker recognition systems, these corpora are aimed at the bilingual and cross channel dimensions. We report on specific data collection efforts at the Linguistic Data Consortium and the research ongoing at the US Federal Bureau of Investigation and MIT Lincoln Laboratories. We cover the design and requirements, the collections and final properties of the corpus integrating discussions of the data preparation, research, technology development and evaluation on a grand scale.
Summary
This paper describes efforts to create corpora to support and evaluate systems that perform speaker recognition where channel and language may vary. Beyond the ongoing evaluation of speaker recognition systems, these corpora are aimed at the bilingual and cross channel dimensions. We report on specific data collection efforts at the...
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An examination of wind shear alert integration at the Dallas/Ft. Worth International Airport (DFW)
August 20, 2003
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-309
Summary
The Dallas / Fort Worth International Airport (DFW) is one of the four demonstration system sites for the Integrated Terminal Weather System (ITWS). One of the primary benefits of the ITWS is a suite of algorithms that utilize data from the Terminal Doppler Weather Radar (TDWR) to generate wind shear alerts. DFW also benefits from a Network Expansion of the Low-Level Wind Shear Advisory System (LLWAS-NE). The LLWAS-NE generated alerts are integrated with the radar-based alerts in ITWS to provide Air Traffic Control (ATC) with a comprehensive set of alert information. This study examines the integrated DFW wind shear alerts with emphasis on circumstances in which the detection performance of the TDWR-based wind shear algorithms was poor. Specific detection problems occur in the following situations: when wind shear events over the airport are aligned along a radial to the TDWR, during "non-traditional" wind shear events, when severe signal attenuation occurs during heavy precipitation over the TDWR radar site, and because of excessive TDWR clutter-residue editing over the airport. In all of the cases examined, the LLWAS-NE issued alerts to ATC that would have otherwise gone unreported.
Summary
The Dallas / Fort Worth International Airport (DFW) is one of the four demonstration system sites for the Integrated Terminal Weather System (ITWS). One of the primary benefits of the ITWS is a suite of algorithms that utilize data from the Terminal Doppler Weather Radar (TDWR) to generate wind shear...
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Operational Experience with TDWR/LLWAS-NE Integration at the Dallas, TX International Airport (DFW)
May 13, 2002
Conference Paper
Published in:
10th Conf. on Aviation, Range and Aerospace Meteorology, 13-16 May 2002, pp. 391-394.
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Summary
At nine major airports, both the Terminal Doppler Weather Radar (TDWR) and Network Extension of the Low-Level Wind shear Advisory System (LLWAS-NE) data will be used to detect and warn Air Traffic Control (ATC) of dangerous wind shear conditions. The integration of wind shear alerts from the two systems is currently being carried out by the TDWR software and will be accomplished by Integrated Terminal Weather System (ITWS) software when the ITWS is installed at these airports. Previous studies of the performance of the TDWR/LLWAS-NE integrated system were carried out at Denver, CO, Dallas, and Orlando, FL. Additionally, there have been recent concerns about false alarms with the LLWAS-NE. In this study, we examine the performance of the integrated system at Dallas-Ft. Worth International Airport (DFW) over a 6-month period in 2000 with particular emphasis on integrated wind shear alerts produced during a number of cases where the TDWR had difficulty making detections due to: 1. radially aligned gust fronts over DFW, 2. radially aligned divergent features, divergence behind gust fronts and divergence embedded within gravity waves, and/or 3. TDWR radome attenuation or excessively aggressive clutter residue editing. DFW is a particularly good airport for such a study because there is an additional TDWR [for Dallas Love airport (DAL)] located in close proximity to DFW and situated in such a way that it provides a very good viewing angle for wind shear events that may not be well characterized by the DFW TDWR radial velocity data. DFW is also an ITWS demonstration system test site with trained meteorologists who review the wind shear detection performance after all convective weather events at DFW.
Summary
At nine major airports, both the Terminal Doppler Weather Radar (TDWR) and Network Extension of the Low-Level Wind shear Advisory System (LLWAS-NE) data will be used to detect and warn Air Traffic Control (ATC) of dangerous wind shear conditions. The integration of wind shear alerts from the two systems is...
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Exploring the possibility of a low altitude gravity wave encounter as the cause of a general aviation accident near Norman Oklahoma on December 6, 1998
September 11, 2000
Conference Paper
Published in:
Proc. Ninth Conf. on Aviation, Range, and Aerospace Meteorology and 20th Conf. on Severe Local Storms, 11-15 September 2000, pp. J46-J49.
Summary
On December 6th, 1998, a fatal accident involving a twin engine Beech Baron occurred near the Max-Westheimer Airport at Norman Oklahoma (OUN). Although the National Transportation Safety Board (NTSB) conducted an extensive investigation into this accident, the probable cause for the accident has yet to be determined. Since the accident occurred outside of weather echoes that might be considered hazardous, it seems difficult to deduce a meteorological explanation for this accident. However, Doppler radar data suggested the presence of wave formations near the site of the accident. This report reflects examination of the data provided by the NTSB.
Summary
On December 6th, 1998, a fatal accident involving a twin engine Beech Baron occurred near the Max-Westheimer Airport at Norman Oklahoma (OUN). Although the National Transportation Safety Board (NTSB) conducted an extensive investigation into this accident, the probable cause for the accident has yet to be determined. Since the accident...
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Measurement of hazardous winter storm phenomena at the Portland OR International Airport
September 11, 2000
Conference Paper
Published in:
Ninth Conf. on Aviation, Range, and Aerospace Meteorology, ARAM, 11-15 September 2000, pp. 525-530.
Summary
Wind shear and lightning are classically associated with summertime convective weather events at airports east of Reno, NV. However, a recent study concluded that severe wind shear and lightning strike events occasionally occur during winter storms at west coast airports. One of the most surprising findings was that the Portland Oregon International Airport (PDX) has operationally significant vertical wind shear and a surprisingly high number of lightning strikes to aircraft within the terminal area during winter storms. The FAA has for a number of years planned to install an ASR-9 Weather System Processor (WSP) at PDX to provide protection against wind shear from microbursts and gust fronts. However, in view of the findings of the west coast weather study (conducted after the FAA's wind shear deployment study was completed, a research program was undertaken to: Better understand the phenomenology associated with the Portland winter storms; Determine whether the baseline ASR-9 Weather System Processor planned for PDX would adequately address operationally significant wind shear and other safety-related weather phenomena; and Identify alternative sensing/data fusion approaches to providing PDX terminal weather decision support if the WSP alone could not adequately provide safety warnings.
Summary
Wind shear and lightning are classically associated with summertime convective weather events at airports east of Reno, NV. However, a recent study concluded that severe wind shear and lightning strike events occasionally occur during winter storms at west coast airports. One of the most surprising findings was that the Portland...
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A refinement of thunderstorm climatology for the terminal radar control airspace
January 10, 1999
Conference Paper
Published in:
8th Conf. on Aviation, Range and Aerospace Meteorology, ARAM, 10-15 January 1999.
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Summary
Convective storms pose a significant threat to aviation safety, and often result in substantial fl ight delays for the commercial aviation industry. The overall impact of these storms is typically based on thunderstorm climatologies and are often one of the factors used in decisions by the US government regarding the operational benefits and allocation of its weather surveillance resources. These climatologies are based on the average number of days that a thunderstorm is observed at a particular airport. Due to the nature of the criteria used to identify a thunderstorm, the climatological statistics often do not accurately represent the number of thunderstorms that impact an airport's operations. The present study utilizes data from the Dallas Ft. Worth International Airport (DFW) and the Orlando International Airport (MCO) to identify deficiencies in the climatological data as it applies to aviation applications. A spatially representative climatology is presented as a more accurate climatology for use in evaluating the impact of convection on an airport's operations. This type of climatological estimate of thunderstorm frequency significantly increases the estimated number of thunderstorms impacting an airport and their associated costs.
Summary
Convective storms pose a significant threat to aviation safety, and often result in substantial fl ight delays for the commercial aviation industry. The overall impact of these storms is typically based on thunderstorm climatologies and are often one of the factors used in decisions by the US government regarding the...
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The benefits of using NEXRAD vertically integrated liquid water as an aviation weather product
January 10, 1999
Conference Paper
Published in:
8th Conf. on Aviation, Range, and Aerospace Meteorology (ARAM), 10-15 January 1999.
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Summary
Over the past five years in which the Integrated Terminal Weather System (ITWS) testbed prototypes have been operational, there have been regular discrepancies noticed between the ASR–9 six–level precipitation product and the NEXRAD six–level maximum composite reflectivity product. (1. The NEXRAD composite product used in this study is the NEXRAD maximum composite reflectivity product which both the FAA and the ITWS use for weather data.). At the three prototypes in Memphis, Orlando and Dallas, staff have recognized that in certain situations the NEXRAD composite reflectivity product, which is the ITWS 100 and 200 nm long–range product, can be as much as three Video Integrator and Processor (VIP) levels higher than the ASR–9 precipitation product. This situation has caused some confusion for users of the ITWS system and concern on the part of system safety monitors. The confusion occurs because the two products do not agree with each other. Rhoda and Pawlak (1998) show that more aircraft will deviate around cells of ASR–9 VIP level 4 or greater than will penetrate them. There is also an aviation rule–of–thumb that pilots and air traffic specialists use which states cells of VIP level 3 or greater should be avoided if possible. This rule is a good guide but cannot be applied to the NEXRAD composite product. While the NEXRAD composite may show a cell with an intensity of level 3 or 4, the cell may contain very little of the higher–intensity precipitation while the bulk of the cell contains only level 2. This problem is magnified in the winter months when bright–band effects contaminate the radar data. Clutter [especially anomalous propagation (AP)] contamination of the composite reflectivity product is also a concern (especially when the AP is adjacent to actual weather returns). Differences between the two products will become more apparent with the fielding of the new ITWS situation display which has the capability of displaying both NEXRAD composite reflectivity and ASR–9 data side by side. In this study, we compare the NEXRAD composite reflectivity product with data from both the ASR–9 weather channel and an ASR–9 mosaic product as well as a Vertically Integrated Liquid water (VIL) product generated from NEXRAD base data.
Summary
Over the past five years in which the Integrated Terminal Weather System (ITWS) testbed prototypes have been operational, there have been regular discrepancies noticed between the ASR–9 six–level precipitation product and the NEXRAD six–level maximum composite reflectivity product. (1. The NEXRAD composite product used in this study is the NEXRAD...
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Thunderstorm induced gravity waves as a potential hazard to commercial aircraft
January 10, 1999
Conference Paper
Published in:
8th Conf. on Aviation, Range and Aerospace Meteorology, ARAM, 10-15 January 1999.
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Summary
Under certain atmospheric conditions, thunderstorm development can induce a phenomenon known as gravity waves (i.e., buoyancy or density waves). These waves are characterized by alternating regions of convergence and divergence over a relatively short distance. Such aerodynamic shear can become hazardous to air traffic if the shear contained within the waves surpasses the threshold for air traffic safety. Gravity waves are particularly hazardous because they develop in seemingly benign weather surrounding the parent thunderstorm and in many cases are not associated with any visual storm feature. Several cases have been studied in which commercial aircraft have encountered gravity waves and have been adversely affected by their encounters. The purpose of this study is to show how gravity waves can have a detrimental effect on aircraft in flight, how gravity waves can be detected, and that need for a detection algorithm exists. With the development of the National Weather Service's Next Generation Radar (WSR–88D NEXRAD) and the Federal Aviation Administration's Terminal Doppler Weather Radar (TDWR), the ability to detect gravity waves exists near many of America's major airports. Since gravity waves are a low–level phenomenon (generally below 2 km), their presence should be of interest to aircraft in the takeoff and landing stages of flight. During operations at Lincoln Laboratory's Integrated Terminal Weather System (ITWS) prototype field site in Dallas, there have been at least two incidents in which commercial aircraft experienced wind shear of at least 40 knots on takeoff, possibly caused by single or multiple gravity wave bands. This study will look at 57 cases of gravity wave formation within the terminal areas of Dallas–Ft. Worth International, Memphis International, and Orlando International airports. Statistics will be compiled to determine the frequency and severity of the gravity waves as well as their duration. The study will include Pilot Reports (PIREPS) from a few of these cases in which aircraft experienced wind shear due to suspected encounters with gravity waves. It is the hope of the author that this study will lead to the development of a detection algorithm that will increase the safety of America's commercial air traffic.
Summary
Under certain atmospheric conditions, thunderstorm development can induce a phenomenon known as gravity waves (i.e., buoyancy or density waves). These waves are characterized by alternating regions of convergence and divergence over a relatively short distance. Such aerodynamic shear can become hazardous to air traffic if the shear contained within the...
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