Publications
Asteroid search operations with the Space Surveillance Telescope
March 5, 2016
Conference Paper
Published in:
2016 IEEE Aerospace Conf., 5-12 March 2016.
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Summary
Over the past two years, the Lincoln Near Earth Asteroid Research (LINEAR) program, funded by the National Aeronautics and Space Administration (NASA), has transitioned to asteroid search operations using the new 3.5-meter wide-field-of-view Space Surveillance Telescope (SST) located at the Atom Site on White Sands Missile Range, N.M. The SST was developed for the Defense Advanced Research Projects Agency (DARPA) by MIT Lincoln Laboratory to help advance the nation's capabilities in space situational awareness. The goals of LINEAR using SST are to continue discovering Near-Earth objects (NEOs) especially focusing on improving knowledge of asteroids 140 meters in diameter and larger. In this paper, we will review results of the first two years of asteroid search operations, during which the SST has delivered over 9.4 million observations to the Minor Planet Center. Recent and planned system improvements will also be discussed.
Summary
Over the past two years, the Lincoln Near Earth Asteroid Research (LINEAR) program, funded by the National Aeronautics and Space Administration (NASA), has transitioned to asteroid search operations using the new 3.5-meter wide-field-of-view Space Surveillance Telescope (SST) located at the Atom Site on White Sands Missile Range, N.M. The SST...
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Vector antenna and maximum likelihood imaging for radio astronomy
March 5, 2016
Conference Paper
Published in:
2016 IEEE Aerospace Conf., 5-12 March 2016.
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Summary
Radio astronomy using frequencies less than ~100 MHz provides a window into non-thermal processes in objects ranging from planets to galaxies. Observations in this frequency range are also used to map the very early history of star and galaxy formation in the universe. Much effort in recent years has been devoted to highly capable low frequency ground-based interferometric arrays such as LOFAR, LWA, and MWA. Ground-based arrays, however, cannot observe astronomical sources below the ionospheric cut-off frequency of ~10 MHz, so the sky has not been mapped with high angular resolution below that frequency. The only space mission to observe the sky below the ionospheric cut-off was RAE-2, which achieved an angular resolution of ~60 degrees in 1973. This work presents alternative sensor and algorithm designs for mapping the sky both above and below the ionospheric cutoff. The use of a vector sensor, which measures the full electric and magnetic field vectors of incoming radiation, enables reasonable angular resolution (~5 degrees) from a compact sensor (~4 m) with a single phase center. A deployable version of the vector sensor has been developed to be compatible with the CubeSat form factor.
Summary
Radio astronomy using frequencies less than ~100 MHz provides a window into non-thermal processes in objects ranging from planets to galaxies. Observations in this frequency range are also used to map the very early history of star and galaxy formation in the universe. Much effort in recent years has been...
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SoK: privacy on mobile devices - it's complicated
March 2, 2016
Conference Paper
Published in:
Proc. on Privacy Enhancing Techn., Vol. 3, 2016, pp. 96-116.
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Summary
Modern mobile devices place a wide variety of sensors and services within the personal space of their users. As a result, these devices are capable of transparently monitoring many sensitive aspects of these users' lives (e.g., location, health, or correspondences). Users typically trade access to this data for convenient applications and features, in many cases without a full appreciation of the nature and extent of the information that they are exposing to a variety of third parties. Nevertheless, studies show that users remain concerned about their privacy and vendors have similarly been increasing their utilization of privacy-preserving technologies in these devices. Still, despite significant efforts, these technologies continue to fail in fundamental ways, leaving users' private data exposed. In this work, we survey the numerous components of mobile devices, giving particular attention to those that collect, process, or protect users' private data. Whereas the individual components have been generally well studied and understood, examining the entire mobile device ecosystem provides significant insights into its overwhelming complexity. The numerous components of this complex ecosystem are frequently built and controlled by different parties with varying interests and incentives. Moreover, most of these parties are unknown to the typical user. The technologies that are employed to protect the users' privacy typically only do so within a small slice of this ecosystem, abstracting away the greater complexity of the system. Our analysis suggests that this abstracted complexity is the major cause of many privacy-related vulnerabilities, and that a fundamentally new, holistic, approach to privacy is needed going forward. We thus highlight various existing technology gaps and propose several promising research directions for addressing and reducing this complexity.
Summary
Modern mobile devices place a wide variety of sensors and services within the personal space of their users. As a result, these devices are capable of transparently monitoring many sensitive aspects of these users' lives (e.g., location, health, or correspondences). Users typically trade access to this data for convenient applications...
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Competing cognitive resilient networks
March 1, 2016
Journal Article
Published in:
IEEE Trans. Cognit. Commun. and Netw., Vol. 2, No. 1, March 2016, pp. 95-109.
Summary
We introduce competing cognitive resilient network (CCRN) of mobile radios challenged to optimize data throughput and networking efficiency under dynamic spectrum access and adversarial threats (e.g., jamming). Unlike the conventional approaches, CCRN features both communicator and jamming nodes in a friendly coalition to take joint actions against hostile networking entities. In particular, this paper showcases hypothetical blue force and red force CCRNs and their competition for open spectrum resources. We present state-agnostic and stateful solution approaches based on the decision theoretic framework. The state-agnostic approach builds on multiarmed bandit to develop an optimal strategy that enables the exploratory-exploitative actions from sequential sampling of channel rewards. The stateful approach makes an explicit model of states and actions from an underlying Markov decision process and uses multiagent Q-learning to compute optimal node actions. We provide a theoretical framework for CCRN and propose new algorithms for both approaches. Simulation results indicate that the proposed algorithms outperform some of the most important algorithms known to date.
Summary
We introduce competing cognitive resilient network (CCRN) of mobile radios challenged to optimize data throughput and networking efficiency under dynamic spectrum access and adversarial threats (e.g., jamming). Unlike the conventional approaches, CCRN features both communicator and jamming nodes in a friendly coalition to take joint actions against hostile networking entities...
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Development of a real-time hardware-in-the-loop power systems simulation platform to evaluate commercial microgrid controllers
February 23, 2016
Technical Report
Published in:
MIT Lincoln Laboratory Report TR-1203
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Summary
This report describes the development of a real-time hardware-in-the-loop (HIL) power system simulation platform to evaluate commercial microgrid controllers. The effort resulted in the successful demonstration of HIL simulation technology at a Technical Symposium organized by the Mass Clean Energy Center (CEC) for utility distribution system engineers, project developers, systems integrators, equipment vendors, academia, regulators, City of Boston officials, and Commonwealth officials. Actual microgrid controller hardware was integrated along with actual, commercial genset controller hardware in a particular microgrid configuration, which included dynamic loads, distributed energy resources (DERs), and conventional power sources. The end product provides the ability to quickly and cost-effectively assess the performance of different microgrid controllers as quantified by certain metrics, such as fuel consumption, power flow management precision at the point of common coupling, load-not-served (LNS) while islanded, peak-shaving kWh, and voltage stability. Additional applications include protection system testing and evaluation, distributed generation prime mover controller testing, integration and testing of distribution control systems, behavior testing and studies of DER controls, detailed power systems analysis, communications testing and integration, and implementation and evaluation of smart grid concepts. Microgrids and these additional applications promise to improve the reliability, resiliency, and efficiency of the nation's aging but critical power distribution systems. This achievement was a collaborative effort between MIT Lincoln Laboratory and industry microgrid controller manufacturers. This work was sponsored by the Department of Homeland Security (DHS), Science and Technology Directorate (S&T) and the Department of Energy (DOE) Office of Electricity Delivery and Energy Reliability.
Summary
This report describes the development of a real-time hardware-in-the-loop (HIL) power system simulation platform to evaluate commercial microgrid controllers. The effort resulted in the successful demonstration of HIL simulation technology at a Technical Symposium organized by the Mass Clean Energy Center (CEC) for utility distribution system engineers, project developers, systems...
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Photonic lantern adaptive spatial mode control in LMA fiber amplifiers
February 22, 2016
Journal Article
Published in:
Opt. Express, Vol. 24, No. 4, 22 February 2016, pp. 3405-13.
Summary
We demonstrate adaptive-spatial mode control (ASMC) in few-moded double-clad large mode area (LMA) fiber amplifiers by using an all-fiber-based photonic lantern. Three single-mode fiber inputs are used to adaptively inject the appropriate superposition of input modes in a multimode gain fiber to achieve the desired mode at the output. By actively adjusting the relative phase of the single-mode inputs, near-unity coherent combination resulting in a single fundamental mode at the output is achieved.
Summary
We demonstrate adaptive-spatial mode control (ASMC) in few-moded double-clad large mode area (LMA) fiber amplifiers by using an all-fiber-based photonic lantern. Three single-mode fiber inputs are used to adaptively inject the appropriate superposition of input modes in a multimode gain fiber to achieve the desired mode at the output. By...
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Raman spectra and cross sections of ammonia, chlorine, hydrogen sulfide, phosgene, and sulfur dioxide toxic gases in the fingerprint region 400-1400 cm-1
February 11, 2016
Journal Article
Published in:
AIP Advances, Vol. 6, No. 2, February 2016, 025310, doi: 10.1063/1.4942109.
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Summary
Raman spectra of ammonia (NH3), chlorine (Cl2), hydrogen sulfide (H2S), phosgene (COCl2), and sulfur dioxide (SO2) toxic gases have been measured in the fingerprint region 400-1400 cm-1. A relatively compact (< 2'x2'x2'), sensitive, 532 nm 10 W CW Raman system with double-pass laser and double-sided collection was used for these measurements. Two Raman modes are observed at 934 and 967 cm-1 in NH3. Three Raman modes are observed in Cl2 at 554, 547, and 539 cm-1, which are due to the 35/35 35/37, and 37/37 Cl isotopes, respectively. Raman modes are observed at 870, 570, and 1151 cm-1 in H2S, COCl2, and SO2, respectively. Values of 3.68 ± 0.26x10-32 cm2/sr (3.68 ± 0.26x10-36 m2/sr), 1.37 ± 0.10x10-30 cm2/sr (1.37 ± 0.10x10-34 m2/sr), 3.25 ± 0.23x10-31 cm2/sr (3.25 ± 0.23x10-35 m2/sr), 1.63 ± 0.14x10-30 cm2/sr (1.63 ± 0.14x10-34 m2/sr), and 3.08 ± 0.22x10-30 cm2/sr (and 3.08 ± 0.22x10-34 m2/sr) were determined for the differential Raman cross section of the 967 cm-1 mode of NH3, sum of the 554, 547, and 539 cm-1 modes of Cl2, 870 cm-1 mode of H2S, 570 cm-1 mode of COCl2, and 1151 cm-1 mode of SO2, respectively, using the differential Raman cross section of 3.56 ± 0.14x10-31 cm2/sr (3.56 ± 0.14x10-35 m2/sr) for the 1285 cm-1 mode of CO2 as the reference.
Summary
Raman spectra of ammonia (NH3), chlorine (Cl2), hydrogen sulfide (H2S), phosgene (COCl2), and sulfur dioxide (SO2) toxic gases have been measured in the fingerprint region 400-1400 cm-1. A relatively compact ( 2'x2'x2'), sensitive, 532 nm 10 W CW Raman system with double-pass laser and double-sided collection was used for these...
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En route sector capacity model final report
January 29, 2016
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-426
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Accurate predictions of en route sector capacity are vital when analyzing the benefits of proposed new air traffic management decision-support tools or new airspace designs. Controller workload is the main determinant of sector capacity. This report describes a new workload-based capacity model that improves upon the Federal Aviation Administration's current Monitor Alert capacity model. Analysts often use Monitor Alert sector capacities in evaluating the benefits of decision-support aids or airspace designs. However, Monitor Alert, which was designed to warn controllers of possible sector overload, sets sector capacity limits based solely on handoff workload and fixed procedural constraints. It ignores the effects of conflict workload and recurring workload (from activities such as monitoring, vectoring, spacing, and metering). Each workload type varies differently as traffic counts and airspace designs are changed. When used for benefits analysis, Monitor Alert's concentration on a single workload type can lead to erroneous conclusions. The new model considers all three workload types. We determine the relative contribution of the three workload types by fitting the model to the upper frontiers that appear in peak daily sector traffic counts from today's system. When we fit the Monitor Alert model to these same peak traffic counts, it can only explain the observed frontiers by hypothesizing large handoff workload. Large handoff workload would imply that decision-support aids should focus on handoff tasks. The new model fits the traffic data with less error, and shows that recurring tasks create significantly more workload in all sectors than do handoff tasks. The new model also shows that conflict workload dominates in very small sectors. These findings suggest that it is more beneficial to develop decision-support aids for recurring tasks and conflict tasks than for handoff tasks.
Summary
Accurate predictions of en route sector capacity are vital when analyzing the benefits of proposed new air traffic management decision-support tools or new airspace designs. Controller workload is the main determinant of sector capacity. This report describes a new workload-based capacity model that improves upon the Federal Aviation Administration's current...
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D4M and large array databases for management and analysis of large biomedical imaging data
January 28, 2016
Conference Paper
Published in:
North East Database Day 2016, 28 January 2016.
Summary
Advances in medical imaging technologies have enabled the acquisition of increasingly large datasets. Current state-of-the-art confocal or multi-photon imaging technology can produce biomedical datasets in excess of 1 TB per dataset. Typical approaches for analyzing large datasets rely on downsampling the original datasets or leveraging distributed computing resources where small subsets of images are processed independently. These approaches require significant overhead on the part of the programmer to load the desired sub-volume from an array of image files into memory. Databases are well suited for indexing and retrieving components of very large datasets and show significant promise for the analysis of 3D volumetric images. In particular, array-based databases such as SciDB utilize an architecture that supports massive parallel processing while also providing database services such as data management and fast parallel queries. In this paper, we will present a new set of tools that leverage the D4M (Dynamic Distributed Dimensional Data Model) toolbox for analyzing giga-voxel biomedical datasets. By combining SciDB and the D4M toolbox, we demonstrate that we can access large volumetric data and perform large-scale bioinformatics analytics efficiently and interactively. We show that it is possible to achieve an ingest rate of 2.8 million entries per second for importing large datasets into SciDB. These tools provide more efficient ways to access random sub-volumes of massive datasets and to process the information that typically cannot be loaded into memory. This work describes the D4M and SciDB tools that we developed and presents the initial performance results.
Summary
Advances in medical imaging technologies have enabled the acquisition of increasingly large datasets. Current state-of-the-art confocal or multi-photon imaging technology can produce biomedical datasets in excess of 1 TB per dataset. Typical approaches for analyzing large datasets rely on downsampling the original datasets or leveraging distributed computing resources where small...
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Comb generator design for SWaP-constrained applications
January 24, 2016
Conference Paper
Published in:
2016 IEEE Radio and Wireless Symp., RWS 2016, 24-27 January 2016.
Summary
Many wireless devices have requirements that emphasize low size, weight and power for increased functionality and extended lifetimes. The additional complexity of these devices mandates the need to dynamically verify that all sub-system functions are fully operational. These tests can only be performed internal to the unit, and a circuit that could be utilized to meet this demand should be constructed to be as simple as possible. This paper presents both a novel set of equations to represent a compact comb generator circuit using a step recovery diode as well as unique sequential measurements of a prototype to provide greater insight into the design. The analyzed circuit requires no bias voltage, and effectively produces harmonics up to 2 GHz with a 2 MHz input signal, which is sufficient for adding built-in-test capability to most wireless devices.
Summary
Many wireless devices have requirements that emphasize low size, weight and power for increased functionality and extended lifetimes. The additional complexity of these devices mandates the need to dynamically verify that all sub-system functions are fully operational. These tests can only be performed internal to the unit, and a circuit...
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