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Experience using active and passive mapping for network situational awareness

Published in:
5th IEEE Int. Symp. on Network Computing and Applications NCA06, 24-26 July 2006, pp. 19-26.

Summary

Passive network mapping has often been proposed as an approach to maintain up-to-date information on networks between active scans. This paper presents a comparison of active and passive mapping on an operational network. On this network, active and passive tools found largely disjoint sets of services and the passive system took weeks to discover the last 15% of active services. Active and passive mapping tools provided different, not complimentary information. Deploying passive mapping on an enterprise network does not reduce the need for timely active scans due to non-overlapping coverage and potentially long discovery times.
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Summary

Passive network mapping has often been proposed as an approach to maintain up-to-date information on networks between active scans. This paper presents a comparison of active and passive mapping on an operational network. On this network, active and passive tools found largely disjoint sets of services and the passive system...

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Assessment of air traffic control productivity enhancements from the Corridor Integrated Weather System (CIWS)

Published in:
MIT Lincoln Laboratory Report ATC-325

Summary

The Air Traffic Control (ATC) productivity benefits attributed to the Corridor Integrated Weather System (CIWS) were assessed using real-time observations of CIWS product usage during three multi-day thunderstorm events in 2005 at eight U.S. Air Route Traffic Control Centers (ARTCCs). CIWS improved ATC productivity by: reducing the time required to develop, coordinate, and implement weather impact mitigation plans; increasing the number of safety and capacity-enhancing plans that were executed (e.g., more efficient, proactive rerouting and greater ability to keep routes open; [and] assisting with FAA staffing decisions. Time savings per consecutive weather day for Traffic Management Coordinators (TMCs) in an ARTCC typically were 20-95 minutes. The overall frequency of capacity-enhancing decisions increased by 177% relative to the CIWS benefits study conducted in 2003. The annual CIWS delay savings are in excess of 92,000 hours. Corresponding airline direct operations cost (DOC) savings exceeded $94M and passenger value of time (PVT) savings exceeded $201M. Annual jet fuel savings exceeded 11M gallons. The ability of the Cleveland ARTCC to develop and execute weather impact mitigation plans improved significantly (e.g., by 50-80%) when CIWS products were available to Area Supervisors as well as to the TMCs.
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Summary

The Air Traffic Control (ATC) productivity benefits attributed to the Corridor Integrated Weather System (CIWS) were assessed using real-time observations of CIWS product usage during three multi-day thunderstorm events in 2005 at eight U.S. Air Route Traffic Control Centers (ARTCCs). CIWS improved ATC productivity by: reducing the time required to...

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Advanced language recognition using cepstra and phonotactics: MITLL system performance on the NIST 2005 Language Recognition Evaluation

Summary

This paper presents a description of the MIT Lincoln Laboratory submissions to the 2005 NIST Language Recognition Evaluation (LRE05). As was true in 2003, the 2005 submissions were combinations of core cepstral and phonotactic recognizers whose outputs were fused to generate final scores. For the 2005 evaluation, Lincoln Laboratory had five submissions built upon fused combinations of six core systems. Major improvements included the generation of phone streams using lattices, SVM-based language models using lattice-derived phonotactics, and binary tree language models. In addition, a development corpus was assembled that was designed to test robustness to unseen languages and sources. Language recognition trends based on NIST evaluations conducted since 1996 show a steady improvement in language recognition performance.
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Summary

This paper presents a description of the MIT Lincoln Laboratory submissions to the 2005 NIST Language Recognition Evaluation (LRE05). As was true in 2003, the 2005 submissions were combinations of core cepstral and phonotactic recognizers whose outputs were fused to generate final scores. For the 2005 evaluation, Lincoln Laboratory had...

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Compensating for mismatch in high-level speaker recognition

Published in:
2006 IEEE Odyssey, the Speaker and Language Recognition Workshop, 28-30 June 2006.

Summary

Speaker recognition using high-level features has been a successful area of exploration. Features obtained from many different levels phones, words, prosodic events, etc. are used to characterize the speaker. A good modeling technique for these features is the support vector machine (SVM). SVMs model the n-gram frequencies from speaker utterances in a high-dimensional SVM feature space and have shown excellent performance over a wide variety of high-level features. A complimentary method of recent exploration in SVM speaker recognition is the use of nuisance attribute projection (NAP). NAP removes directions from SVM feature space that are superfluous to the task of speaker recognition channel information, session variability, etc. In this paper, we consider the application of NAP to high-level speaker recognition. We describe the difficulties in applying this method and propose solutions. We also conduct experiments showing that NAP can reduce variability in SVM feature space leading to improved performance.
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Summary

Speaker recognition using high-level features has been a successful area of exploration. Features obtained from many different levels phones, words, prosodic events, etc. are used to characterize the speaker. A good modeling technique for these features is the support vector machine (SVM). SVMs model the n-gram frequencies from speaker utterances...

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Experiments with lattice-based PPRLM language identification

Summary

In this paper we describe experiments conducted during the development of a lattice-based PPRLM language identification system as part of the NIST 2005 language recognition evaluation campaign. In experiments following LRE05 the PPRLM-lattice sub-system presented here achieved a 30s/primary condition EER of 4.87%, making it the single best performing recognizer developed by the MIT-LL team. Details of implementation issues and experimental results are presented and interactions with backend score normalization are explored.
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Summary

In this paper we describe experiments conducted during the development of a lattice-based PPRLM language identification system as part of the NIST 2005 language recognition evaluation campaign. In experiments following LRE05 the PPRLM-lattice sub-system presented here achieved a 30s/primary condition EER of 4.87%, making it the single best performing recognizer...

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Understanding scores in forensic speaker recognition

Summary

Recent work in forensic speaker recognition has introduced many new scoring methodologies. First, confidence scores (posterior probabilities) have become a useful method of presenting results to an analyst. The introduction of an objective measure of confidence score quality, the normalized cross entropy, has resulted in a systematic manner of evaluating and designing these systems. A second scoring methodology that has become popular is support vector machines (SVMs) for high-level features. SVMs are accurate and produce excellent results across a wide variety of token types-words, phones, and prosodic features. In both cases, an analyst may be at a loss to explain the significance and meaning of the score produced by these methods. We tackle the problem of interpretation by exploring concepts from the statistical and pattern classification literature. In both cases, our preliminary results show interesting aspects of scores not obvious from viewing them "only as numbers."
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Summary

Recent work in forensic speaker recognition has introduced many new scoring methodologies. First, confidence scores (posterior probabilities) have become a useful method of presenting results to an analyst. The introduction of an objective measure of confidence score quality, the normalized cross entropy, has resulted in a systematic manner of evaluating...

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Assessment of air traffic control productivity enhancements from the Corridor Integrated Weather System (CIWS) - executive summary

Published in:
MIT Lincoln Laboratory Report ATC-325-1

Summary

In an era of significant federal government budget austerity for civil aviation operations, it has become essential to improve Air Traffic Control (ATC) productivity. This report summarizes the results of an exploratory field measurement program conducted during summer 2005 to assess ATC productivity benefits of the Corridor Integrated Weather System (CIWS). Real-time observations of CIWS product usage during multi-day thunderstorm events were carried out at eight U.S. Air Route Traffic Control Centers (ARTCC). The real time observations data were used in conjunction with specific in-depth case study analyses to assess the CIWS productivity enhancements associated with convective weather impact mitigation plan development and implementation. Comparisons of ARTCC operations between facilities with and without access to CIWS were alos made to further identify CIWS contributions to improved ATC productivity.
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Summary

In an era of significant federal government budget austerity for civil aviation operations, it has become essential to improve Air Traffic Control (ATC) productivity. This report summarizes the results of an exploratory field measurement program conducted during summer 2005 to assess ATC productivity benefits of the Corridor Integrated Weather System...

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Nonlinear equalization for RF receivers

Published in:
Proc. Conf. on High Performance Computer Modernization Program, 26-29 June 2006, pp. 303-307.

Summary

This paper describes the need for High Performance Computing (HPC) to facilitate the development and implementation of a nonlinear equalizer that is capable of mitigating and/or eliminating nonlinear distortion to extend the dynamic range of radar front-end receivers decades beyond the analog state-of-the-art. The search space for the optimal nonlinear equalization (NLEQ) solution is computationally intractable using only a single desktop computer. However, we have been able to leverage a combination of an efficient greedy search with the high performance computing technologies of LLGrid and MatlabMPI to construct an NLEQ architecture that is capable of extending the dynamic range of Radar front-end receivers by over 25dB.
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Summary

This paper describes the need for High Performance Computing (HPC) to facilitate the development and implementation of a nonlinear equalizer that is capable of mitigating and/or eliminating nonlinear distortion to extend the dynamic range of radar front-end receivers decades beyond the analog state-of-the-art. The search space for the optimal nonlinear...

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Ultra-linear superwideband chirp generator using digital compensation

Published in:
IEEE MTT-S Int. Microwave Symp., 11-16 June 2006, pp. 403-406.

Summary

A novel digital compensation technique is applied to linearize the frequency generation of a superwideband chirp. Ultra-linear, low-noise swept local oscillators (SLO) are critical to the two-tone dynamic range performance of compressive receivers. The proposed technique enables full software control of the chirp linearity, slope, and offset to allow automated real-time calibration and testing, including automatic compensation for temperature variation. This approach combines recently available commercial high-speed digital, mixed-signal, and analog integrated circuits along with microwave components to create a 15.5-24 GHz chirp over 60 nsec with
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Summary

A novel digital compensation technique is applied to linearize the frequency generation of a superwideband chirp. Ultra-linear, low-noise swept local oscillators (SLO) are critical to the two-tone dynamic range performance of compressive receivers. The proposed technique enables full software control of the chirp linearity, slope, and offset to allow automated...

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Operational evaluation of runway status lights

Published in:
Lincoln Laboratory Journal, Vol. 16, No. 1, June 2006, pp. 123-146.

Summary

To maintain safe separation of aircraft on the airport surface, air traffic controllers issue verbal clearances to pilots to sequence aircraft arrivals, departures, and runway crossings. Although controllers and pilots work together successfully most of the time, mistakes do occasionally happen, causing several hundred runway incursions a year and, less frequently, near misses and collisions in the United States. With this rate of incursions, it is imperative to have an independent warning system as a backup to the current system. Runway status lights, a system of automated, surveillance-driven stoplights, have been designed to provide this backup function. The lights are installed at runway-taxiway intersections and at departure points along the runways. They provide a clear signal to pilots crossing or departing from a runway, warning them of potential conflicts with traffic already on the runway. Existing FAA-installed radar surveillance is coupled with Lincoln Laboratory-developed algorithms to generate the light commands. To be compatible with operations at the busiest airports, the algorithms must drive the lights such that during normal operations pilots will almost never encounter a red light when it is safe to cross or depart from a runway. A minimal error rate must be maintained even in the face of inevitable imperfections in the surveillance system used to drive the safety logic. A prototype runway status light system has been designed at Lincoln Laboratory and installed at the Dallas/Fort Worth International Airport, where Laboratory personnel have worked with the FAA to complete an operational evaluation of the system, demonstrating the feasibility of runway status lights in the challenging, complex environment of one of the world's busiest airports.
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Summary

To maintain safe separation of aircraft on the airport surface, air traffic controllers issue verbal clearances to pilots to sequence aircraft arrivals, departures, and runway crossings. Although controllers and pilots work together successfully most of the time, mistakes do occasionally happen, causing several hundred runway incursions a year and, less...

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