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An analysis of the impacts of wake vortex restrictions at LGA

September 16, 2002
  |
Project Report
Author:
Shawn S. Allan
…
Published in:
Project Report ATC-305, MIT Lincoln Laboratory
Topic:
weather
R&D area:
R&D group:

Summary

Wake vortex restrictions at New York's La Guardia airport cause a significant reduction in capacity when aircraft land on runway 22 and depart on runway 31. This report presents an analysis of the annual delay cost at LGA associated with the wake vortex restrictions. We find that the delay due to these restrictions exceeds 4000 hours annually, and that these restrictions cause a significant workload increase to controllers at both La Guardia and the New York TRACON. If traffic levels were to increase 10% from their February 2001 levels, the corresponding increase in delay due to the wake vortex restrictions would rise from 30 hours a day to over 400 hours a day in this runway configuration. It is also found that for a meaningful increase in passenger capacity in this runway configuration to be as demand grows, restrictions must be reduced from their current levels. If the percentage of heavy/757's doubled at LGA, there would be no increase in passenger capacity while daily delays in this runway configuration due to current wake vortex separation standards would increase by 250 hours.
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Summary

Wake vortex restrictions at New York's La Guardia airport cause a significant reduction in capacity when aircraft land on runway 22 and depart on runway 31. This report presents an analysis of the annual delay cost at LGA associated with the wake vortex restrictions. We find that the delay due...

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An analysis of the impacts of wake vortex restrictions at LGA

2-D processing of speech with application to pitch estimation

September 16, 2002
  |
Conference Paper
Author:
Thomas F. Quatieri
Published in:
7th Int. Conf. on Spoken Language Processing, ICSLP 2002, 16-20 September 2002.
Topic:
speech enhancement
R&D area:
R&D group:

Summary

In this paper, we introduce a new approach to two-dimensional (2-D) processing of the one-dimensional (1-D) speech signal in the time-frequency plane. Specifically, we obtain the shortspace 2-D Fourier transform magnitude of a narrowband spectrogram of the signal and show that this 2-D transformation maps harmonically-related signal components to a concentrated entity in the new 2-D plane. We refer to this series of operations as the "grating compression transform" (GCT), consistent with sine-wave grating patterns in the spectrogram reduced to smeared impulses. The GCT forms the basis of a speech pitch estimator that uses the radial distance to the largest peak in the GCT plane. Using an average magnitude difference between pitch-contour estimates, the GCT-based pitch estimator is shown to compare favorably to a sine-wave-based pitch estimator for all-voiced speech in additive white noise. An extension to a basis for two-speaker pitch estimation is also proposed.
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Summary

In this paper, we introduce a new approach to two-dimensional (2-D) processing of the one-dimensional (1-D) speech signal in the time-frequency plane. Specifically, we obtain the shortspace 2-D Fourier transform magnitude of a narrowband spectrogram of the signal and show that this 2-D transformation maps harmonically-related signal components to a...

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2-D processing of speech with application to pitch estimation

Approaches to language identification using Gaussian mixture models and shifted delta cepstral features

September 16, 2002
  |
Conference Paper
Author:
Pedro A. Torres-Carrasquillo
…
Published in:
Proc. Int. Conf. on Spoken Language Processing, INTERSPEECH, 16-20 September 2002, pp. 33-36, 82-92.
Topic:
language recognition
R&D area:
R&D group:

Summary

Published results indicate that automatic language identification (LID) systems that rely on multiple-language phone recognition and n-gram language modeling produce the best performance in formal LID evaluations. By contrast, Gaussian mixture model (GMM) systems, which measure acoustic characteristics, are far more efficient computationally but have tended to provide inferior levels of performance. This paper describes two GMM-based approaches to language identification that use shifted delta cepstra (SDC) feature vectors to achieve LID performance comparable to that of the best phone-based systems. The approaches include both acoustic scoring and a recently developed GMM tokenization system that is based on a variation of phonetic recognition and language modeling. System performance is evaluated on both the CallFriend and OGI corpora.
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Summary

Published results indicate that automatic language identification (LID) systems that rely on multiple-language phone recognition and n-gram language modeling produce the best performance in formal LID evaluations. By contrast, Gaussian mixture model (GMM) systems, which measure acoustic characteristics, are far more efficient computationally but have tended to provide inferior levels...

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Approaches to language identification using Gaussian mixture models and shifted delta cepstral features

An analysis of the impacts of wake vortex restrictions at LGA

September 16, 2002
  |
Project Report
Author:
Shawn S. Allan
…
Published in:
MIT Lincoln Laboratory Report ATC-305
Topic:
weather
R&D area:
R&D group:

Summary

Wake vortex restrictions at New York's La Guardia airport cause a significant reduction in capacity when aircraft land on runway 22 and depart on runway 31. This report presents an analysis of the annual delay cost at LGA associated with the wake vortex restrictions. We find that the delay due to these restrictions exceeds 4000 hours annually, and that these restrictions cause a significant workload increase to controllers at both La Guardia and the New York TRACON. If traffic levels were to increase 10% from their February 2001 levels, the corresponding increase in delay due to the wake vortex restrictions would rise from 30 hours a day to over 400 hours a day in this runway configuration. It is also found that for a meaningful increase in passenger capacity in this runway configuration to be as demand grows, restrictions must be reduced from their current levels. If the percentage of heavy/757's doubled at LGA, there would be no increase in passenger capacity while daily delays in this runway configuration due to current wake vortex separation standards would increase by 250 hours.
READ LESS

Summary

Wake vortex restrictions at New York's La Guardia airport cause a significant reduction in capacity when aircraft land on runway 22 and depart on runway 31. This report presents an analysis of the annual delay cost at LGA associated with the wake vortex restrictions. We find that the delay due...

READ MORE
An analysis of the impacts of wake vortex restrictions at LGA

CSKETCH image processing library

August 21, 2002
  |
Project Report
Author:
John P. Morgan
…
Published in:
MIT Lincoln Laboratory Report ATC-283
Topic:
image processing
R&D area:
R&D group:

Summary

The CSKETCH image processing library is a collection of C++ classes and global functions which comprise a development environment for meteorological algorithms. The library is best thought of as a 'tool-kit' which contains many standard mathematical and signal processing functions often employed in the analysis of weather radar data. A tutorial-style introduction to the library is given, complete with many examples of class and global function usage. Included is an in-depth look at the main class of the library, the SKArray class, which is a templatized and encapsulated class for storing numerical data arrays of one, two, or three dimensions. Following the tutorial is a complete reference for the library which describes all publicly-available class data members and class member functions, as well as all global functions included in the library.
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Summary

The CSKETCH image processing library is a collection of C++ classes and global functions which comprise a development environment for meteorological algorithms. The library is best thought of as a 'tool-kit' which contains many standard mathematical and signal processing functions often employed in the analysis of weather radar data. A...

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CSKETCH image processing library

Improving the high altitude performance of tail-controlled endoatmospheric missiles

August 5, 2002
  |
Journal Article
Author:
Paul Zarchan
…
Published in:
AIAA Guidance, Navigation, and Control Conf., 5-8 August 2002.
Topic:
missile defense
R&D area:
R&D group:

Summary

It is demonstrated that at high altitude the performance of a tail-controlled aerodynamic missile can degrade because of the existence of low frequency right-half plane zeroes in the airframe transfer function when either proportional navigation or optimal guidance is used. A new guidance law that accounts for the airframe zeroes is developed numerically and shown to have superior performance to existing guidance laws at the higher altitudes. Although no closed-form solution for the guidance law is presented, the resultant numerical values for the control gains of the guidance law can easily be stored as a multidimensional table in existing on-board flight control computers. Two methodologies for computing the guidance law control gains are presented.
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Summary

It is demonstrated that at high altitude the performance of a tail-controlled aerodynamic missile can degrade because of the existence of low frequency right-half plane zeroes in the airframe transfer function when either proportional navigation or optimal guidance is used. A new guidance law that accounts for the airframe zeroes...

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Improving the high altitude performance of tail-controlled endoatmospheric missiles

Gust front update algorithm for the Weather Systems Processor (WSP)

July 29, 2002
  |
Project Report
Author:
Seth W. Troxel
Published in:
MIT Lincoln Laboratory Report ATC-275
Topic:
signal processing
R&D area:
R&D group:

Summary

The Gust Front Update Algorithm (GFUP) is part of the gust front product generation chain for the ASR-9 Weather Systems Processor (WSP). GFUP processes gust front detection and position prediction data output by the Machine Intelligent Gust Front Algorithm (MIGFA), and uses an internal timer to schedule generation of updated current and 10- and 20-minute gust front predictions at 1-minute intervals. By substituting appropriate interval gust front forecast data from MIGFA, the locations of gust fronts shown on the user display are updated at a rate that is faster than the radar base data processed by MIGFA. Prior to output, the updated curve position data are smothered by GFUP using a tangent-spline interpolation algorithm. This document provides a general overview and high level description of the GFUP algorithm.
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Summary

The Gust Front Update Algorithm (GFUP) is part of the gust front product generation chain for the ASR-9 Weather Systems Processor (WSP). GFUP processes gust front detection and position prediction data output by the Machine Intelligent Gust Front Algorithm (MIGFA), and uses an internal timer to schedule generation of updated...

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Gust front update algorithm for the Weather Systems Processor (WSP)

300x faster Matlab using MatlabMPI

July 18, 2002
  |
Journal Article
Author:
Jeremy Kepner
Published in:
https://arxiv.org/abs/astro-ph/0207389
Topic:
supercomputing
R&D area:
R&D group:

Summary

The true costs of high performance computing are currently dominated by software. Addressing these costs requires shifting to high productivity languages such as Matlab. MatlabMPI is a Matlab implementation of the Message Passing Interface (MPI) standard and allows any Matlab program to exploit multiple processors. MatlabMPI currently implements the basic six functions that are the core of the MPI point-to-point communications standard. The key technical innovation of MatlabMPI is that it implements the widely used MPI "look and feel" on top of standard Matlab file I/O, resulting in an extremely compact (~250 lines of code) and "pure" implementation which runs anywhere Matlab runs, and on any heterogeneous combination of computers. The performance has been tested on both shared and distributedmemory parallel computers (e.g. Sun, SGI, HP, IBM and Linux). MatlabMPI can match the bandwidth of C based MPI at large message sizes. A test image filtering application using MatlabMPI achieved a speedup of ~300 using 304 CPUs and ~15% of the theoretical peak (450 Gigaflops) on an IBM SP2 at the Maui High Performance Computing Center. In addition, this entire parallel benchmark application was implemented in 70 software-lines-of-code (SLOC) yielding 0.85 Gigaflop/SLOC or 4.4 CPUs/SLOC, which are the highest values of these software price performance metrics ever achieved for any application. The MatlabMPI software will be made available for download.
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Summary

The true costs of high performance computing are currently dominated by software. Addressing these costs requires shifting to high productivity languages such as Matlab. MatlabMPI is a Matlab implementation of the Message Passing Interface (MPI) standard and allows any Matlab program to exploit multiple processors. MatlabMPI currently implements the basic...

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300x faster Matlab using MatlabMPI

Potential benefits of reducing wake-related aircraft spacing at the Dallas/Fort Worth International Airport

July 12, 2002
  |
Project Report
Author:
Justin D. Shaw
…
Published in:
MIT Lincoln Laboratory Report ATC-304
Topic:
air traffic control
R&D area:
R&D group:

Summary

Measurements and modeling of wake vortices reveal that the Federal Aviation Administration's (FAA) minimum separation requirements for departing aircraft are often overly conservative. If the separation times following heavy aircraft can be safely reduced, considerable savings will be realized. The Dallas/Fort Worth International Airport (DFW) experiences departure delays daily. Banks of departing aircraft often create a significant queue at the end of the runway, with aircraft waiting between 10-20 minutes to depart. Additional delays occur during weather recovery operations after the terminal airspace has been impacted by thunderstorms. This report produces projected delay and cost benefits of implementing reduced wake spacing for departing aircraft at DFW. The benefits are calculated by simulating aircraft departures during both clear weather and weather recovery operations, using current and possible reduced spacings. The difference in delay values using different separation standards is used to calculate a cost savings to the airlines. The benefits for a single day are extended to a yearly approximation based on the estimated number of days that the separation criteria could be safely reduced. Departure information from February 19, 2001 is analyzed for clear weather operations. The simulation reveals a savings of $4.7 million/yr when the separation criteria is reduced from the current practice of 110 seconds to 90 seconds. A further reduction in the separation criteria to 60 seconds pushes the maximum savings to almost $10 million/yr. The daily savings for a weather recovery operation is $19,600 for weather impacts between 15-60 minutes and a reduction in spacing fiom the current 110 seconds to 90 seconds. The average increases to $36,200 when the spacing is reduced to 60 seconds. Significant thunderstorm events impacted the DFW terminal airspace 59 times during 2001 leading to projected yearly savings of greater than $2.1 million for a 60 second separation criteria following heavies.
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Summary

Measurements and modeling of wake vortices reveal that the Federal Aviation Administration's (FAA) minimum separation requirements for departing aircraft are often overly conservative. If the separation times following heavy aircraft can be safely reduced, considerable savings will be realized. The Dallas/Fort Worth International Airport (DFW) experiences departure delays daily. Banks...

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Potential benefits of reducing wake-related aircraft spacing at the Dallas/Fort Worth International Airport

High-speed, electronically shuttered solid-state imager technology

July 8, 2002
  |
Conference Paper
Author:
Robert K. Reich
…
Published in:
Rev. Sci. Instrum. Vol. 74, No. 3, Pt. II, March 2003, pp. 2027-2031 (Proceedings of the 14th Topical Conference on High-Temperature Plasma Diagnostics, 8-11 July 2002)
Topic:
electronics
R&D area:
R&D group:

Summary

Electronically shuttered solid-state imagers are being developed for high-speed imaging applications. A 5 cmx5 cm, 512x512-element, multiframe charge-coupled device (CCD) imager has been fabricated for the Los Alamos National Laboratory DARHT facility that collects four sequential image frames at megahertz rates. To operate at fast frame rates with high sensitivity, the imager uses an electronic shutter technology designed for back-illuminated CCDs. The design concept and test results are described for the burst-frame-rate imager. Also discussed is an evolving solid-state imager technology that has interesting characteristics for creating large-format x-ray detectors with short integration times (100 ps to 1 ns). Proposed device architectures use CMOS technology for high speed sampling (tens of picoseconds transistor switching times). Techniques for parallel clock distribution, that triggers the sampling of x-ray photoelectrons, will be described that exploit features of CMOS technology.
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Summary

Electronically shuttered solid-state imagers are being developed for high-speed imaging applications. A 5 cmx5 cm, 512x512-element, multiframe charge-coupled device (CCD) imager has been fabricated for the Los Alamos National Laboratory DARHT facility that collects four sequential image frames at megahertz rates. To operate at fast frame rates with high sensitivity...

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High-speed, electronically shuttered solid-state imager technology
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