Publications
SET characterization in logic circuits fabricated in a 3DIC technology
December 1, 2011
Journal Article
Published in:
IEEE Trans. Nuclear Sci., Vol. 58, No. 6, December 2011, pp. 2555-2562.
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Summary
Single event transients are characterized for the first time in logic gate circuits fabricated in a novel 3DIC technology where SET test circuits are vertically integrated on three tiers in a 20-um-thick layer. This 3D technology is extremely will suited for high-density circuit integration because of the small dimension the tier-to-tier circuit interconnects, which are 1.25-um-wide-through-oxide-vias. Transient pulse width distributions were characterized simultaneously on each tier during exposure to krypton heavy ions. The difference in SET pulse width and cross-section among the three tiers is discussed. Experimental test results are explaine dby considering the electrical characteristics of the FETs on the 2D wafers before 3D integration, and by considering the energy deposited by the Kr ions passing through the various material laters of the 3DIC stack. We also show that the backmetal layer available on the upper tiers can be used to tune independently the nFET and pFET current drive, and change the SET pulse width and cross-section. This 3DIC technology appears to be a good candidate for space applications.
Summary
Single event transients are characterized for the first time in logic gate circuits fabricated in a novel 3DIC technology where SET test circuits are vertically integrated on three tiers in a 20-um-thick layer. This 3D technology is extremely will suited for high-density circuit integration because of the small dimension the...
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Investigating acoustic correlates of human vocal fold vibratory phase asymmetry through modeling and laryngeal high-speed videoendoscopy
December 1, 2011
Journal Article
Published in:
J. Acoust. Soc. Am., Vol. 130, No. 6, December 2011, pp. 3999-4009.
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Vocal fold vibratory asymmetry is often associated with inefficient sound production through its impact on source spectral tilt. This association is investigated in both a computational voice production model and a group of 47 human subjects. The model provides indirect control over the degree of left-right phase asymmetry within a nonlinear source-filter framework, and high-speed videoendoscopy provides in vivo measures of vocal fold vibratory asymmetry. Source spectral tilt measures are estimated from the inverse-filtered spectrum of the simulated and recorded radiated acoustic pressure. As expected, model simulations indicated that increasing left-right phase asymmetry induces steeper spectral tilt. Subject data, however, reveal that none of the vibratory asymmetry measures correlates with spectral tilt measures. Probing further into physiological correlates of spectral tilt that might be affected by asymmetry, the glottal area waveform is parameterized to obtain measures of the open phase (open/plateau quotient) and closing phase (speed/closing quotient). Subjects' left-right phase asymmetry exhibits low, but statistically significant, correlations with speed quotient (r=0.45) and closing quotient (r=-0.39). Results call for future studies into the effect of asymmetric vocal fold vibrartion on glottal airflow and the associated impact on voice source spectral properties and vocal efficiency.
Summary
Vocal fold vibratory asymmetry is often associated with inefficient sound production through its impact on source spectral tilt. This association is investigated in both a computational voice production model and a group of 47 human subjects. The model provides indirect control over the degree of left-right phase asymmetry within a...
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Exploring the variable sky with LINEAR : photometric recalibration with the Sloan Digital Sky Survey
December 1, 2011
Journal Article
Published in:
Astronomical J., Vol. 142, No. 6, December 2011.
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We describe photometric recalibration of data obtained by the asteroid survey LINEAR. Although LINEAR was designed for astrometric discovery of moving objects, the data set described here contains over 5 billion photometric measurements for about 25 million objects, mostly stars. We use Sloan Digital Sky Survey (SDSS) data from the overlapping ~10,000 deg2 of sky to recalibrate LINEAR photometry and achieve errors of 0.03 mag for sources not limited by photon statistics with errors of 0.2 mag at r ~ 18. With its 200 observations per object on average, LINEAR data provide time domain information for the brightest four magnitudes of the SDSS survey. At the same time, LINEAR extends the deepest similar wide-area variability survey, the Northern Sky Variability Survey, by 3 mag.We briefly discuss the properties of about 7000 visually confirmed periodic variables, dominated by roughly equal fractions of RR Lyrae stars and eclipsing binary stars, and analyze their distribution in optical and infrared color?color diagrams. The LINEAR data set is publicly available from the SkyDOT Web site.
Summary
We describe photometric recalibration of data obtained by the asteroid survey LINEAR. Although LINEAR was designed for astrometric discovery of moving objects, the data set described here contains over 5 billion photometric measurements for about 25 million objects, mostly stars. We use Sloan Digital Sky Survey (SDSS) data from the...
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Face recognition despite missing information
November 15, 2011
Journal Article
Published in:
HST 2011, IEEE Int. Conf. on Technologies for Homeland Security, 15-17 November 2011, pp. 475-480.
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Missing or degraded information continues to be a significant practical challenge facing automatic face representation and recognition. Generally, existing approaches seek either to generatively invert the degradation process or find discriminative representations that are immune to it. Ideally, the solution to this problem exists between these two perspectives. To this end, in this paper we show the efficacy of using probabilistic linear subspace modes (in particular, variational probabilistic PCA) for both modeling and recognizing facial data under disguise or occlusion. From a discriminative perspective, we verify the efficacy of this approach for attenuating the effect of missing data due to disguise and non-linear speculars in several verification experiments. From a generative view, we show its usefulness in not only estimating missing information but also understanding facial covariates for image reconstruction. In addition, we present a least-squares connection to the maximum likelihood solution under missing data and show its intuitive connection to the geometry of the subspace learning problem.
Summary
Missing or degraded information continues to be a significant practical challenge facing automatic face representation and recognition. Generally, existing approaches seek either to generatively invert the degradation process or find discriminative representations that are immune to it. Ideally, the solution to this problem exists between these two perspectives. To this...
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Lincoln Laboratory 1030/1090 MHz monitoring, March-June 2010
November 15, 2011
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-372
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Traffic Alert and Collision Avoidance System (TCAS) behavior in New England airspace is being monitored and analyzed, making use of an omni-directional 1030/1090 MHz receiver. The receiver system, located in Lexington, Massachusetts, and operated by MIT Lincoln Laboratory, is used to record data for subsequent analysis in non-real-time. This is the second report of MIT Lincoln Laboratory 1030/1090 MHz monitoring, covering the period March through June 2010. There are three main areas of study: 1. 1030 MHz data related to TCAS air-to-air coordination and other communications, 2. 1030 and 1090 MHz data related to TCAS surveillance, and 3. 1090 MHZ Extended Squitter data, i.e., the Mode S implementation of Automatic Dependent Surveillance-Broadcast (ADS-B). In addition to a summary of results, this report answers specific questions raised during the previous 2009 analysis and attempts to provide insights into the meaning of the data with respect to TCAS operation. This four-month period will be used to baseline 1030/1090 MHz activity in the New England area. Future plans call for the 1030/1090 MHz receiver to be moved so that limited data recording can be performed at various TCAS RA monitoring system (TRAMS) sites throughout the NAS.
Summary
Traffic Alert and Collision Avoidance System (TCAS) behavior in New England airspace is being monitored and analyzed, making use of an omni-directional 1030/1090 MHz receiver. The receiver system, located in Lexington, Massachusetts, and operated by MIT Lincoln Laboratory, is used to record data for subsequent analysis in non-real-time. This is...
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Evaluation of Consolidated Storm Prediction for Aviation (CoSPA) 0-8 hour convective weather forecast using the airspace flow program blockage-based capacity forecast ("The Matrix")
November 9, 2011
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-385
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The CoSPA 0-8 hour convective weather forecast provides deterministic forecast products that can be used by strategic traffic management planners, and can be readily translated into forecasts of aviation capacity impacts for use in automated decision support tools. An operational CoSPA prototype was evaluated at several FAA Air Traffic Control facilities during the summer of 2010. As part of this evaluation, CoSPA forecasts were translated into forecasts of capacity impacts on traffic flows through two Flow Constrained Areas (FCAA05 and FCAA08) commonly used to control arrival traffic into the highly congested northeastern United States. This report describes an objective and operationally relevant evaluation of the accurancy of CoSPA-based forecasts of FCA capacity.
Summary
The CoSPA 0-8 hour convective weather forecast provides deterministic forecast products that can be used by strategic traffic management planners, and can be readily translated into forecasts of aviation capacity impacts for use in automated decision support tools. An operational CoSPA prototype was evaluated at several FAA Air Traffic Control...
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Cyber situational awareness through operational streaming analysis
November 7, 2011
Conference Paper
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MILCOM 2011, IEEE Military Communications Conf., 7-10 November 2011, pp. 1152-1157.
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As the scope and scale of Internet traffic continue to increase the task of maintaining cyber situational awareness about this traffic becomes ever more difficult. There is strong need for real-time on-line algorithms that characterize high-speed / high-volume data to support relevant situational awareness. Recently, much work has been done to create and improve analysis algorithms that operate in a streaming fashion (minimal CPU and memory utilization) in order to calculate important summary statistics (moments) of this network data for the purpose of characterization. While the research literature contains improvements to streaming algorithms in terms of efficiency and accuracy (i.e. approximation with error bounds), the literature lacks research results that demonstrate streaming algorithms in operational situations. The focus of our work is the development of a live network situational awareness system that relies upon streaming algorithms for the determination of important stream characterizations and also for the detection of anomalous behavior. We present our system and discuss its applicability to situational awareness of high-speed networks. We present refinements and enhancements that we have made to a well-known streaming algorithm and improve its performance as applied within our system. We also present performance and detection results of the system when it is applied to a live high-speed mid-scale enterprise network.
Summary
As the scope and scale of Internet traffic continue to increase the task of maintaining cyber situational awareness about this traffic becomes ever more difficult. There is strong need for real-time on-line algorithms that characterize high-speed / high-volume data to support relevant situational awareness. Recently, much work has been done...
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A usable interface for location-based access control and over-the-air keying in tactical environments
November 7, 2011
Conference Paper
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MILCOM 2011, IEEE Military Communications Conf., 7-10 November 2011, pp. 1480-1486.
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This paper presents a usable graphical interface for specifying and automatically enacting access control rules for applications that involve dissemination of data among mobile tactical devices. A specific motivating example is unmanned aerial vehicles (UAVs), where the mission planner or operator needs to control the conditions under which specific receivers can access the UAV?s video feed. We implemented a prototype of this user interface as a plug-in for FalconView, a popular mission planning application.
Summary
This paper presents a usable graphical interface for specifying and automatically enacting access control rules for applications that involve dissemination of data among mobile tactical devices. A specific motivating example is unmanned aerial vehicles (UAVs), where the mission planner or operator needs to control the conditions under which specific receivers...
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Dedicated vs. distributed: a study of mission survivability metrics
November 7, 2011
Conference Paper
Published in:
MILCOM 2011, IEEE Military Communications Conf., 7-10 November 2011, pp. 1345-1350.
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A traditional trade-off when designing a mission critical network is whether to deploy a small, dedicated network of highly reliable links (e.g. dedicated fiber) or a largescale, distributed network of less reliable links (e.g. a leased line over the Internet). In making this decision, metrics are needed that can express the reliability and security of these networks. Previous work on this topic has widely focused on two approaches: probabilistic modeling of network reliabilities and graph theoretic properties (e.g. minimum cutset). Reliability metrics do not quantify the robustness, the ability to tolerate multiple link failures, in a distributed network. For example, a fully redundant network and a single link can have the same overall source-destination reliability (0.9999), but they have very different robustness. Many proposed graph theoretic metrics are also not sufficient to capture network robustness. Two networks with identical metric values (e.g. minimum cutset) can have different resilience to link failures. More importantly, previous efforts have mainly focused on the source-destination connectivity and in many cases it is difficult to extend them to a general set of requirements. In this work, we study network-wide metrics to quantitatively compare the mission survivability of different network architectures when facing malicious cyber attacks. We define a metric called relative importance (RI), a robustness metric for mission critical networks, and show how it can be used to both evaluate mission survivability and make recommendations for its improvement. Additionally, our metric can be evaluated for an arbitrarily general set of mission requirements. Finally, we study the probabilistic and deterministic algorithms to quantify the RI metric and empirically evaluate it for sample networks.
Summary
A traditional trade-off when designing a mission critical network is whether to deploy a small, dedicated network of highly reliable links (e.g. dedicated fiber) or a largescale, distributed network of less reliable links (e.g. a leased line over the Internet). In making this decision, metrics are needed that can express...
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Efficient transmission of DoD PKI certificates in tactical networks
November 7, 2011
Conference Paper
Published in:
MILCOM 2011, IEEE Military Communications Conf., 7-10 November 2011, pp. 1739-1747.
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The DoD vision of real-time information sharing and net-centric services available to warfighters at the tactical edge is challenged by low-bandwidth and high-latency tactical network links. Secured tactical applications require transmission of digital certificates that contribute a major portion of data in most secure sessions, which further increases response time for users and drains device power. In this paper we present a simple and practical approach to alleviating this problem. We develop a dictionary of data common across DoD PKI certificates to prime general-purpose data compression of certificates, resulting in a significant reduction (about 50%) of certificate sizes. This reduction in message size translates in to faster response times for the users. For example, a mutual authentication of a client and a server over the Iridium satellite link is expected to be sped up by as much as 3 sec. This approach can be added directly to tactical applications with minimal effort, or it can be deployed as part of an intercepting network proxy, completely transparent to applications.
Summary
The DoD vision of real-time information sharing and net-centric services available to warfighters at the tactical edge is challenged by low-bandwidth and high-latency tactical network links. Secured tactical applications require transmission of digital certificates that contribute a major portion of data in most secure sessions, which further increases response time...
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