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Measurement of aerosol-particle trajectories using a structured laser beam

June 1, 2007
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Journal Article
Author:
William D. Herzog
…
Published in:
Appl. Opt., Vol. 46, No. 16, 1 June 2007, pp. 3150-3155.
Topic:
lasers
R&D area:
R&D group:

Summary

What is believed to be a new concept for the measurement of micrometer-sized particle trajectories in an inlet air stream is introduced. The technique uses a light source and a mask to generate a spatial pattern of light within a volume in space. Particles traverse the illumination volume and elastically scatter light to a photodetector where the signal is recorded in time. The detected scattering waveform is decoded to find the particle trajectory. A design is presented for the structured laser beam, and the accuracy of the technique in determining particle position is demonstrated. It is also demonstrated that the structured laser beam can be used to measure and then correct for the spatially dependent instrument-response function of an optical-scattering-based particle-sizing system for aerosols.
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Summary

What is believed to be a new concept for the measurement of micrometer-sized particle trajectories in an inlet air stream is introduced. The technique uses a light source and a mask to generate a spatial pattern of light within a volume in space. Particles traverse the illumination volume and elastically...

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Measurement of aerosol-particle trajectories using a structured laser beam

A new compact range facility for antenna and radar target measurements

June 1, 2007
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Journal Article
Author:
Michael W. Shields
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Published in:
Lincoln Laboratory Journal, Vol. 16, No. 2, June 2007, pp. 381-391.
Topic:
antennas
R&D area:
R&D group:

Summary

A new antenna and radar-cross-section measurements facility consisting of four anechoic chambers has recently been constructed at Lincoln Laboratory on Hanscom Air Force Base. One of the chambers is a large compact range facility that operates over the 400 MHz to 100 GHz band, and consists, in part, of a large temperature-controlled rectangular chamber lined with radar-absorbing material that is arranged to reduce scattering; a composite rolled-edge offset-fed parabolic reflector; a robotic multi-feed antenna system; and a radar instrumentation system. Additionally, the compact range facility includes a gantry/crane system that is used to move large antennas and radar targets onto a positioning system that provides the desired aspect angles for measurements of antenna patterns and radar cross section. This compact range system provides unique test capabilities to support rapid prototyping of antennas and radar targets.
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Summary

A new antenna and radar-cross-section measurements facility consisting of four anechoic chambers has recently been constructed at Lincoln Laboratory on Hanscom Air Force Base. One of the chambers is a large compact range facility that operates over the 400 MHz to 100 GHz band, and consists, in part, of a...

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A new compact range facility for antenna and radar target measurements

Air traffic management decision support during convective weather

June 1, 2007
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Journal Article
Author:
Mark E. Weber
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Published in:
Lincoln Laboratory Journal, Vol. 16, No. 2, June 2007, pp. 263-276.
Topic:
air traffic control
R&D area:
R&D group:

Summary

Flight delays caused by thunderstorms are a significant and growing problem for airlines and the flying public. Thunderstorms disrupt the structured, preplanned flight routing and control process that is used to handle dense air traffic streams in congested airspace. Today's coping strategies are developed by traffic flow management (TFM) specialists who interpret weather measurements and forecasts to develop delay and rerouting strategies. The effectiveness of these strategies is limited by the lack of quantitative models for the capacity impacts of thunderstorms, and by the difficulty of developing and executing timely response strategies during rapidly changing convective weather. In this article, we describe initial work to develop more effective response strategies. We first review insights gained during operational testing of a simple but highly effective Route Availability Planning Tool that can significantly reduce convective-weather induced departure delays at congested airports. We then discuss work to develop core technical capabilities and applications that address broader TFM problems, including en route congestion. Objective models for airspace capacity reductions caused by thunderstorms are discussed, as is an associated scheduling algorithm that exploits the capacity estimates to develop broad-area TFM strategies that minimize delay. We conclude by discussing candidate real-time applications and airspace system performance analysis that is enabled by our weather-capacity models and optimal scheduling algorithm.
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Summary

Flight delays caused by thunderstorms are a significant and growing problem for airlines and the flying public. Thunderstorms disrupt the structured, preplanned flight routing and control process that is used to handle dense air traffic streams in congested airspace. Today's coping strategies are developed by traffic flow management (TFM) specialists...

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Air traffic management decision support during convective weather

Enhanced regional situational awareness

June 1, 2007
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Journal Article
Author:
Curtis W. Davis III
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Published in:
Lincoln Laboratory Journal, Vol. 16, No. 2, June 2007, pp. 355-380.
Topic:
aircraft
R&D area:
R&D group:

Summary

Airspace protection in the capital area is provided by an Integrated Air Defense System (IADS) created through the coordinated response of U.S. government and local law-enforcement agencies, including the Department of Defense, the Department of Homeland Security, the Federal Aviation Administration, and the Capitol Police. The IADS includes U.S. Coast Guard helicopters, fighter aircraft, and airborne early-warning aircraft cued by surveillance radars. Under Operation Noble Eagle, the response to a threat includes warning flares deployed from fighter aircraft and, ultimately, the use of surface and air-launched missiles. Selecting the appropriate response requires a means for rapidly assessing the aircraft threat. New and existing sensors must be simultaneously cued to the target of interest and integrated with existing sources of information to display a common-air-picture display to support the decision makers. This article describes the development of an Enhanced Regional Situation Awareness system, an integrated sensing and decision support system developed for the complex and busy airspace surrounding the National Capital Region.
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Summary

Airspace protection in the capital area is provided by an Integrated Air Defense System (IADS) created through the coordinated response of U.S. government and local law-enforcement agencies, including the Department of Defense, the Department of Homeland Security, the Federal Aviation Administration, and the Capitol Police. The IADS includes U.S. Coast...

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Enhanced regional situational awareness

Improving air traffic management group decision-making during severe convective weather

June 1, 2007
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Conference Paper
Author:
James E. Evans
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Published in:
11th World Conf. on Transport Research, June 2007.
Topic:
air traffic management
R&D area:
R&D group:

Summary

There is an urgent need to enhance the efficiency of United States (U.S.) air traffic management (ATM) decision-making when convective weather occurs. Thunderstorm ATM decisions must be made under considerable time pressure with inadequate information (e.g., missing or ambiguous), high stakes, and poorly defined procedures. Often, multiple decisions are considered simultaneously; each requiring coordination amongst a heterogeneous set of decision-makers. Recent operational experience in the use of improved convective weather decision support systems in the Northeast quadrant of the U.S. is reviewed in the context of literature on individual and team decision-making in complex environments. Promising areas of research are identified.
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Summary

There is an urgent need to enhance the efficiency of United States (U.S.) air traffic management (ATM) decision-making when convective weather occurs. Thunderstorm ATM decisions must be made under considerable time pressure with inadequate information (e.g., missing or ambiguous), high stakes, and poorly defined procedures. Often, multiple decisions are considered...

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Improving air traffic management group decision-making during severe convective weather

The Traffic Alert and Collision Avoidance System

June 1, 2007
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Journal Article
Author:
James K. Kuchar
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Published in:
Lincoln Laboratory Journal, Vol. 16, No. 2, June 2007, pp. 277-296.
Topic:
collision avoidance
R&D area:
R&D group:

Summary

The Traffic Alert and Collision Avoidance System (TCAS) has had extraordinary success in reducing the risk of mid-air collisions. Now mandated on all large transport aircraft, TCAS has been in operation for more than a decade and has prevented several catastrophic accidents. TCAS is a unique decision support system in the sense that it has been widely deployed (on more than 25,000 aircraft worldwide) and is continuously exposed to a high-tempo, complex air traffic system. TCAS is the product of carefully balancing and integrating sensor characteristics, tracker and aircraft dynamics, maneuver coordination, operational constraints, and human factors in time-critical situations. Missed or late threat detections can lead to collisions, and false alarms may cause pilots to lose trust in the system and ignore alerts, underscoring the need for a robust system design. Building on prior experience, Lincoln Laboratory recently examined potential improvements to the TCAS algorithms and monitored TCAS activity in the Boston area. Now the Laboratory is pursuing new collision avoidance technologies for unmanned aircraft.
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Summary

The Traffic Alert and Collision Avoidance System (TCAS) has had extraordinary success in reducing the risk of mid-air collisions. Now mandated on all large transport aircraft, TCAS has been in operation for more than a decade and has prevented several catastrophic accidents. TCAS is a unique decision support system in...

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The Traffic Alert and Collision Avoidance System

SiGe IC-based mm-wave imager

May 27, 2007
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Conference Paper
Author:
Helen H. Kim
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Published in:
2007 IEEE Int. Symp. on Circuits and Systems, 27-30 May 2007, pp. 1975-1978.
Topic:
detection systems
R&D area:
R&D group:

Summary

Millimeter-wave radiation and detection offers the possibility of detecting concealed weapons. Passive imaging measures the mm-wave radiation emitted from target objects. A passive mm-wave imager and the designs affecting the overall system performance are discussed. With low power receiver architecture and SiGe ICs, a focal plane based full staring array is feasible and can provide a high thermal resolution, ~1.1K at >10Hz frame rate.
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Summary

Millimeter-wave radiation and detection offers the possibility of detecting concealed weapons. Passive imaging measures the mm-wave radiation emitted from target objects. A passive mm-wave imager and the designs affecting the overall system performance are discussed. With low power receiver architecture and SiGe ICs, a focal plane based full staring array...

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SiGe IC-based mm-wave imager

Technical assessment of the impact of decommissioning the TDWR on terminal weather services

May 23, 2007
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Project Report
Author:
John Y. Cho
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Published in:
MIT Lincoln Laboratory Report ATC-331
Topic:
radar
R&D area:
R&D group:

Summary

Details of a technical study that was part of a larger investigation assessing terminal weather services impacts of decommissioning the Terminal Doppler Weather Radar (TDWR) are presented. Effects on two key areas for safety and delay-reduction benefits are examined: low-altitude wind shear visibility and the Integrated Terminal Weather System (ITWS) Terminals Winds (TWINS) product. It is concluded that the information conted provided by the TDWR cannot, in general, be effectively replaced by other candidate radar systems such as the Airport Surveillance Radar (ASR-9) equipped with a Weather Systems Processor (WSP) or the Next Generation Weather Radar (NEXRAD).
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Summary

Details of a technical study that was part of a larger investigation assessing terminal weather services impacts of decommissioning the Terminal Doppler Weather Radar (TDWR) are presented. Effects on two key areas for safety and delay-reduction benefits are examined: low-altitude wind shear visibility and the Integrated Terminal Weather System (ITWS)...

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Technical assessment of the impact of decommissioning the TDWR on terminal weather services

Making network intrusion detection work with IPsec

May 11, 2007
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Technical Report
Author:
Cynthia D. McLain
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Published in:
MIT Lincoln Laboratory Report TR-1121
Topic:
cryptography
R&D area:
R&D group:

Summary

Network-based intrusion detection systems (NIDSs) are one component of a comprehensive network security solution. The use of IPsec, which encrypts network traffic, renders network intrusion detection virtually useless unless traffic is decrypted at network gateways. One alternative to NIDSs, host-based intrusion detection systems (HIDSs), provides some of the functionality of NIDSs but with limitations. HIDSs cannot perform a network-wide analysis and can be subverted if a host is compromised. We propose an approach to intrusion detection that combines HIDS, NIDS, and a version of IPsec that encrypts the header and the body of IP packets separately. We refer to the latter generically as Two-Key IPsec. We show that all of the network events currently detectable by the Snort NIDS on unencrypted network traffic are also detectable on encrypted network traffic using this approach. The NIDS detects network-level events that HIDSs have trouble detecting and HIDSs detect application-level events that can't be detected by the NIDS.
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Summary

Network-based intrusion detection systems (NIDSs) are one component of a comprehensive network security solution. The use of IPsec, which encrypts network traffic, renders network intrusion detection virtually useless unless traffic is decrypted at network gateways. One alternative to NIDSs, host-based intrusion detection systems (HIDSs), provides some of the functionality of...

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Making network intrusion detection work with IPsec

MIT Lincoln Laboratory multimodal person identification system in the CLEAR 2007 Evaluation

May 8, 2007
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Conference Paper
Author:
Kevin Brady
Published in:
2nd Annual Classification of Event Activities and Relationships/Rich Transcription Evaluations, 8-11 May 2008, pp. 240-247.
Topic:
speaker recognition
R&D area:
R&D group:

Summary

A description of the MIT Lincoln Laboratory system used in the person identification task of the recent CLEAR 2007 Evaluation is documented in this paper. This task is broken into audio, visual, and multimodal subtasks. The audio identification system utilizes both a GMM and a SVM subsystem, while the visual (face) identification system utilizes an appearance-based [Kernel] approach for identification. The audio channels, originating from a microphone array, were preprocessed with beamforming and noise preprocessing.
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Summary

A description of the MIT Lincoln Laboratory system used in the person identification task of the recent CLEAR 2007 Evaluation is documented in this paper. This task is broken into audio, visual, and multimodal subtasks. The audio identification system utilizes both a GMM and a SVM subsystem, while the visual...

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MIT Lincoln Laboratory multimodal person identification system in the CLEAR 2007 Evaluation
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