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Detection and characterization of human trafficking networks using unsupervised scalable text template matching

Summary

Human trafficking is a form of modern-day slavery affecting an estimated 40 million victims worldwide, primarily through the commercial sexual exploitation of women and children. In the last decade, the advertising of victims has moved from the streets to websites on the Internet, providing greater efficiency and anonymity for sex traffickers. This shift has allowed traffickers to list their victims in multiple geographic areas simultaneously, while also improving operational security by using multiple methods of electronic communication with buyers; complicating the ability of law enforcement to disrupt these illicit organizations. In this paper, we address this issue and present a novel unsupervised and scalable template matching algorithm for analyzing and detecting complex organizations operating on adult service websites. The algorithm uses only the advertisement content to uncover signature patterns in text that are indicative of organized activities and organizational structure. We apply this method to a large corpus of adult service advertisements retrieved from backpage.com, and show that the networks identified through the algorithm match well with surrogate truth data derived from phone number networks in the same corpus. Further exploration of the results show that the proposed method provides deeper insights into the complex structures of sex trafficking organizations, not possible through networks derived from phone numbers alone. This method provides a powerful new capability for law enforcement to more completely identify and gather evidence about trafficking networks and their operations.
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Summary

Human trafficking is a form of modern-day slavery affecting an estimated 40 million victims worldwide, primarily through the commercial sexual exploitation of women and children. In the last decade, the advertising of victims has moved from the streets to websites on the Internet, providing greater efficiency and anonymity for sex...

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Cloud computing in tactical environments

Summary

Ground personnel at the tactical edge often lack data and analytics that would increase their effectiveness. To address this problem, this work investigates methods to deploy cloud computing capabilities in tactical environments. Our approach is to identify representative applications and to design a system that spans the software/hardware stack to support such applications while optimizing the use of scarce resources. This paper presents our high-level design and the results of initial experiments that indicate the validity of our approach.
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Summary

Ground personnel at the tactical edge often lack data and analytics that would increase their effectiveness. To address this problem, this work investigates methods to deploy cloud computing capabilities in tactical environments. Our approach is to identify representative applications and to design a system that spans the software/hardware stack to...

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Development and use of a comprehensive humanitarian assessment tool in post-earthquake Haiti

Summary

This paper describes a comprehensive humanitarian assessment tool designed and used following the January 2010 Haiti earthquake. The tool was developed under Joint Task Force -- Haiti coordination using indicators of humanitarian needs to support decision making by the United States Government, agencies of the United Nations, and various non-governmental organizations. A set of questions and data collection methodology were developed by a collaborative process involving a broad segment of the Haiti humanitarian relief community and used to conduct surveys in internally displaced person settlements and surrounding communities for a four-month period starting on 15 March 2010. Key considerations in the development of the assessment tool and data collection methodology, representative analysis results, and observations from the operational use of the tool for decision making are reported. The paper concludes with lessons learned and recommendations for design and use of similar tools in the future.
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Summary

This paper describes a comprehensive humanitarian assessment tool designed and used following the January 2010 Haiti earthquake. The tool was developed under Joint Task Force -- Haiti coordination using indicators of humanitarian needs to support decision making by the United States Government, agencies of the United Nations, and various non-governmental...

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Multipath modeling for simulating the performance of the Microwave Landing System

Published in:
Lincoln Laboratory Journal, Vol. 2, No. 3, Fall 1989, pp. 459-474.

Summary

The Microwave Landing System (MLS) will be deployed throughout the world in the 1990s to provide precision guidance to aircraft for approach and landing at airports. At Lincoln Laboratory, we have developed a computer-based simulation that models the performance of MLS and takes into account the multipath effects of buildings, the surrounding terrain, and other aircraft in the vicinity. The simulation has provided useful information about the effects of multipath on MLS performance.
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Summary

The Microwave Landing System (MLS) will be deployed throughout the world in the 1990s to provide precision guidance to aircraft for approach and landing at airports. At Lincoln Laboratory, we have developed a computer-based simulation that models the performance of MLS and takes into account the multipath effects of buildings...

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Comparison of various elevation angle estimation techniques

Published in:
Natl. Telecommunications Conf., Houston, TX, 1-4 December 1980.

Summary

The angular resolution and tracking of closely spaced targets is a classical radar problem which is receiving increased attention, and terrain multipath (e.g., reflections) has long been recognized to be a principal limitation on the achievable accuracy of radar elevation trackers at low elevation angles. A variety of techniques have been proposed for improved elevation angle estimation: however, comparative analysis based on field comparable data has not been available to date. In this paper, distributions of multipath scattered power, described in a companion paper, are used to compare several elevation angle estimation techniques: (1) conventional monopulse; (2) off-boresight monopulse; (3) double null monopulse; (4) single edge processing as is used for flare processing in the Microwave Landing System; and (5) a maximum entropy technique based estimator.
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Summary

The angular resolution and tracking of closely spaced targets is a classical radar problem which is receiving increased attention, and terrain multipath (e.g., reflections) has long been recognized to be a principal limitation on the achievable accuracy of radar elevation trackers at low elevation angles. A variety of techniques have...

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Experimental measurement of the low angle terrain scattering interference environment

Published in:
Natl. Telecommunications Conf., Houston, TX, 30 November-4 December 1980.

Summary

This paper presents the results of an experimental program to obtain a better quantitative understanding of low angle microwave propagation phenomena needed to assess the potential for improved elevation tracking performance. It has long been recognized that terrain multipath (e.g., reflections and/or shadowing) are a principal limitation on the achievable accuracy of radar elevation trackers and/or landing navigation aids at low angles; however, there has been a paucity of relevant experimental data over irregular terrain. The experimental data presented were obtained with a 26 lambda L-band array and a 57 lambda C-band array at a variety of sites in eastern Massachusetts with vegetated and/or rolling terrain. It is shown that specular reflections appear to be the predominant multipath source and these are predictable from a model based on scattering from tilted plates.
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Summary

This paper presents the results of an experimental program to obtain a better quantitative understanding of low angle microwave propagation phenomena needed to assess the potential for improved elevation tracking performance. It has long been recognized that terrain multipath (e.g., reflections and/or shadowing) are a principal limitation on the achievable...

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PALM - a system for precise aircraft location

Published in:
J. of the Institute of Navigation, Vol. 23, No. 3, Fall 1976, pp. 257-261.

Summary

The Precision Altitude and Landing Monitor (PALM) is intended to provide accurate stand-alone three-dimensional position data for aircraft equipped with standard beacon transponders using ground equipment designed for low life cycle cost. The PALM program, to the present time, has focused on an experimental evaluation of the accuracy of elevation measurements. The results of these measurements have successfully validated the theoretical prediction of a 1-mrad (0.06 degree) elevation accuracy at low elevation angles. The key features in the PALM design include (1) No new avionics required, i.e., it uses standard aircraft transponder. IFPALM is used as the data base for certain ground-to-air messages, a standard VHF or DABS data link could be employed. (2) High accuracy position data, i.e., a 1-mrad rms error in elevation and in azimuth at low elevation angles. (3) Broad airspace coverage, e.g., 40 degrees in elevation, 120 degrees in azimuth (expandable to 360 degrees), and several tens of miles in range. (4) Low life cycle equipment cost, i.e., it incorporates a fixed passive receiving antenna array and a minicomputer to perform the signal processing necessary for interference rejection.
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Summary

The Precision Altitude and Landing Monitor (PALM) is intended to provide accurate stand-alone three-dimensional position data for aircraft equipped with standard beacon transponders using ground equipment designed for low life cycle cost. The PALM program, to the present time, has focused on an experimental evaluation of the accuracy of elevation...

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Optimum elevation angle estimation in the presence of ground reflection multipath

Published in:
MIT Lincoln Laboratory Report TN-1976-11

Summary

An optimal trade-off between the width of the subarray aperture and the width of the interferometer base line is performed that achieves a specified elevation angle estimation error while minimizing the overall height of the interferometer configuration. Statistical decision theory is used to analyze and design a separate sensor for resolving the interferometer ambiguities. For coverage over 2.5 to 40 in elevation and +/-60 in azimuth, two 7-wavelength subarrays separated by 8 wavelengths are sufficient for 1-mrad elevation-angle errors. A 4-element nonuniformly spaced array of dipole antennas mounted on tri-plane reflectors renders the probability of an ambiguity error less than 0.004.
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Summary

An optimal trade-off between the width of the subarray aperture and the width of the interferometer base line is performed that achieves a specified elevation angle estimation error while minimizing the overall height of the interferometer configuration. Statistical decision theory is used to analyze and design a separate sensor for...

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Experimental validation of PALM - a system for precise aircraft location

Summary

A ground based system to precisely locate aircraft in three dimensions based on transponder replies has been designed. Field tests have been conducted to validate the design of the elevation performance. This document reports on the principle of operation, experimental hardware and field test of the Precision Altitude and Landing Monitor (PALM). The key features incorporated in the PALM design include: (a) no new avionics required, i.e., uses standard aircraft transponder; (b) high accuracy position data, i.e., a 1-mrad (0.06 degree) rms error in elevation and in azimuth; (c) broad airspace coverage, e.g., 40 degrees in elevation, 120 degrees in azimuth (expandable to 360 degrees) and several 10s of miles in range; and (d) low life cycle equipment cost. The high accuracy in the difficult airport multipath environment is a direct result of (a) newly developed antenna synthesis procedure, (b) the development of adaptive multipath suppression techniques, and (c) the use of digital signal processing. The program, to date, has focused on an experimental evaluation of the elevation performance. The electronics required for the tests have been built into a self-powered van to facilitate experiments at remote airports. The actual flight test data demonstrated experimental errors on the order of 1 mrad; moreover, as predicted by theory, the resulting errors were essentially independent of elevation angle. Potential applications for the PALM position data include parallel approach monitoring, independent altitude monitoring, and/or performance assurance monitoring of landing guidance systems.
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Summary

A ground based system to precisely locate aircraft in three dimensions based on transponder replies has been designed. Field tests have been conducted to validate the design of the elevation performance. This document reports on the principle of operation, experimental hardware and field test of the Precision Altitude and Landing...

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Accuracy limitations of range-range (spherical) multilateration systems

Author:
Published in:
MIT Lincoln Laboratory Report TN-1973-43

Summary

This report presents a novel procedure for determining the accuracy of range-range (or spherical) multilateration systems. The procedure is a generalization of one previously described for hyperbolic multilateration systems. A central result is a demonstration that the inverse of the covariance matrix for positional errors corresponds to the moment of inertia matrix of a simple mass configuration. The insight afforded by this fact is used to resolve a number of questions relating to accuracy. Specific questions addressed include the following: 1. How does accuracy depend upon the number of receivers? 2. How does accuracy depend upon the deployment of receivers? 3. What is the maximum accuracy that can be obtained from N receivers? How should the receivers be deployed to maximize accuracy? 4. How do altitude errors compare to horizontal errors in satellite-based systems? In ground-based systems?
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Summary

This report presents a novel procedure for determining the accuracy of range-range (or spherical) multilateration systems. The procedure is a generalization of one previously described for hyperbolic multilateration systems. A central result is a demonstration that the inverse of the covariance matrix for positional errors corresponds to the moment of...

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