2011–2012 Technical Seminar Series

Members of the technical staff at MIT Lincoln Laboratory are pleased to present these technical seminars to interested college and university groups. Costs related to the staff members' visits for these seminars will be assumed by the Laboratory.

To arrange a technical seminar, please contact

College Recruiting Program Administrator
Human Resources Department
MIT Lincoln Laboratory
244 Wood Street
Lexington, Massachusetts 02420-9108
781-981-2465
email: collegerecr@ll.mit.edu

and provide the following information:

  • A rank-ordered list of requested seminars
  • Preferred date/time options
  • A description of the target audience
Cells treated with DRACO

One of the new seminars for 2011–2012

Broad-Spectrum Antiviral Therapeutics

The image on the left illustrates that cells infected with rhinovirus (the common cold) are returned to health after treated with the broad-spectrum antiviral therapeutic, DRACO (for Double-stranded RNA [dsRNA] Activated Caspase Oligomerizer), with no toxicity.

 

Index of 2011–2012 Seminars

Air Traffic Control

Data Mining, Decision Support, and Data Fusion

Homeland Protection

Solid State Devices, Materials, and Processes

Space Control Technology

Communication Systems and Cyber Security

Optical Propagation and Technology

Radar and Signal Processing

Systems and Architecture

SEMINAR ABSTRACTS

Air Traffic Control

Human-System Integration in
Aeronautical Decision Support Systems

Dr. Hayley J. Davison Reynolds1
MIT Lincoln Laboratory

MIT Lincoln Laboratory has had a successful history of integrating decision support systems into the air traffic control (ATC) domain, even though the introduction of new technologies often meets user resistance. Because of the nature of the work, air traffic controllers heavily rely on certain technologies and decision processes to maintain a safe operating environment while maximizing efficiency. This reliance on familiar technology and processes makes the introduction of a new tool into the environment a difficult task, even though the tool may ultimately improve the decision and raise levels of safety and/or efficiency of the operation. Poorly integrated systems can result in users being disappointed by a system that provides information for which they have no concept of use, or more likely, that results in the system’s not being used despite its existence in the array of available information systems; neither option yields the benefits for which the tool was designed.

In this seminar, a practical methodology for designing and fielding decision support systems that maximizes the potential of effective integration of the system into the users' operational context will be presented. Several examples of Federal Aviation Administration air traffic control decision support prototype systems designed by Lincoln Laboratory, including the Route Availability Planning Tool (RAPT) and the Tower Flight Data Manager (TFDM), will be described to demonstrate this process. Included in the presentation will be areas in which the designers ran into roadblocks in making the systems effective and the combination of qualitative and quantitative techniques used to eventually integrate the system well in the field, yielding measurable operational benefits.

1 PhD, Aeronautics and Astronautics, Massachusetts Institute of Technology

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Integrating Unmanned Aircraft Systems Safely
into the National Airspace System

Dr. Rodney E. Cole1
MIT Lincoln Laboratory

Unmanned aircraft systems (UASs) such as the Air Force's Global Hawk and Predator are increasingly employed by the military and Department of Homeland Security in roles that require sharing airspace with civilian aircraft. Missions include pilot training, border patrol, highway and agricultural observation, and disaster management. Because of the pressure for widespread access for UASs to the national airspace and the risk of collision with passenger aircraft, UAS operators must find a way to integrate with manned aircraft with a very high degree of safety. The key to safe integration of UAS into the national airspace is the development and assessment of "sense and avoid" (SAA) technologies to replace the manned aircraft pilot's ability to "see and avoid" other aircraft.

MIT Lincoln Laboratory is conducting research on numerous fronts to address safe and flexible UAS integration with commercial and general aviation aircraft. Research areas include development of sophisticated computer models, which simulate millions of encounters between UAS and civilian aircraft to characterize airspace hazards and collision rates. These models can then be applied to assess the performance of SAA algorithms designed to maintain separation, "well clear," between UAS and civilian aircraft while observing and adhering to established right-of-way rules. The Laboratory is also conducting ground-breaking research in the area of collision avoidance and is pursuing a probabilistic approach to collision avoidance that considers all possible trajectory encounters and their likelihood. This approach offers the potential to provide increased safety with decreased false alarms over conventional techniques and is a candidate for future Traffic Collision Avoidance Systems (TCAS) and UAS SAA applications.

The Laboratory is also working with the Department of Defense (DoD) and Department of Homeland Security to develop Ground-Based Sense and Avoid (GBSAA) and Airborne Sense and Avoid (ABSAA) surveillance architectures that may satisfy the Federal Aviation Administrations's (FAA's) requirement for replacing the onboard pilot's "see and avoid" function. Under DoD sponsorship, Lincoln Laboratory is developing a net-centric GBSAA test bed that will be utilized in an operational or simulation-over-live environment to collect data and operator feedback that can then be used to support future certification with the FAA. This seminar will provide a broad overview of the Laboratory's efforts in UAS airspace integration and next-generation aircraft collision avoidance algorithms and will provide an overview of the GBSAA test bed that is under development for the DoD.

1PhD, Mathematics, University of Colorado–Boulder

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Modeling the Impacts of Thunderstorms on Air Traffic Operations

Mr. Richard A. DeLaura1
MIT Lincoln Laboratory

Weather accounts for 70% of the cost of air traffic delays—about $28 billion annually—within the United States National Airspace System (NAS). Most weather-related delays occur during the summer months, when thunderstorms affect air traffic, particularly in the crowded Northeast. The task of air traffic management, complicated even in the best of circumstances, can become overwhelmingly complex as air traffic managers struggle to route traffic reliably through rapidly evolving thunderstorms. A new generation of air traffic management decision support tools promises to reduce air traffic delays by accounting for the potential effects of convective weather, such as thunderstorms, on air traffic flow. Underpinning these tools are models that translate high-resolution convective weather forecasts into estimates of impact on aviation operations.

This seminar will present the results of new research to develop models of pilot decision making and air traffic capacity in the presence of thunderstorms. The models will be described, initial validation will be presented, and sources of error and uncertainty will be discussed. Finally, some applications of these models and directions for future research will be briefly described.

1AB, Physics, Harvard University

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Multifunction Phased-Array Radar for U.S.
Civil-Sector Surveillance Needs

Dr. Mark E. Weber1 
Dr. Jeffrey S. Herd2
MIT Lincoln Laboratory

This seminar describes a concept study for possible future utilization of active electronically scanned (AES) radars to provide weather and aircraft surveillance functions in U.S. airspace. If transmit-receive element costs decrease sufficiently, multifunction AES radars might prove to be a cost-effective alternative to current surveillance radars (WSR-88D, TDWR, ASR, ARSR) since the number of required radars would be reduced and maintenance and logistics infrastructure would be consolidated. A radar configuration that provides terminal-area and long-range aircraft surveillance and weather measurement capability is described, and a radar network design that replicates or exceeds current airspace coverage is presented. Key technology issues are examined, including transmit-receive elements, overlapped subarrays, the digital beamformer, and weather and aircraft postprocessing algorithms. The seminar concludes with a discussion of how such a radar network might integrate with next-generation weather and aircraft surveillance architectures.

1PhD, Space Physics and Astronomy, Rice University
2PhD, Electrical Engineering, University of Massachusetts–Amherst

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Runway Status Lights

Dr. James R. Eggert1 
MIT Lincoln Laboratory

Aviation's single deadliest accident was the result of a runway incursion at Tenerife, Canary Islands, in 1977. Runway incursion accidents and incidents continue to occur, and their reduction has been identified by the National Transportation Safety Board and Federal Aviation Administration as one of the most important aviation safety challenges.

There are many initiatives under way to prevent or mitigate runway incursions. MIT Lincoln Laboratory has been on the forefront of one of the most promising technological approaches to addressing the runway incursion problem through a system called Runway Status Lights. These lights are located on runways and on taxiway entrances to runways, and indicate to pilots whether the runway is safe to enter, cross, or depart. The lights are driven automatically by computer processing of surveillance derived from multiple surveillance systems. The Runway Status Light system is therefore the result of the careful integration of surveillance fusion, aircraft behavior identification and prediction, operational safety algorithms, and human factors analysis needed to create an operational prototype suitable for testing at a major airport.

This seminar will introduce the need for runway incursion prevention, discuss the runway status lights concept, and describe the success of ongoing operational testing at Dallas/Fort Worth International Airport, San Diego International Airport, and Los Angeles International Airport. The seminar will conclude with a description of new initiatives, including additional types of lights for use at complex airports and their deployment at Boston Logan International Airport.

1PhD, Physics, Harvard University

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The Future of Air Traffic Control Tower Decision Support

Dr. James K. Kuchar1
MIT Lincoln Laboratory

The Federal Aviation Administration's Next Generation Air Transportation System (NextGen) initiative promises a number of new capabilities including enhanced surveillance, communications, and decision support. One area of critical need is the nation's air traffic control tower infrastructure, which has evolved only incrementally over the last several decades. Today, controllers must mentally integrate multiple separate information displays to determine how to best manage arrivals, departures, and taxiing aircraft at an airport. The result is a brittle system that is prone to significant delay, excess fuel burn, and environmental impact.

This seminar will discuss the development of a prototype system that consolidates tower information systems, enables electronic exchange of information inside and outside the tower, and provides integrated decision support capabilities to more efficiently manage the airport environment. Issues related to system architecture, data interfaces, algorithms, displays, and field testing will be discussed. The seminar concludes with a look ahead toward the wider integration of air traffic control automation systems and their technical challenges.

1 PhD, Aeronautics and Astronautics, Massachusetts Institute of Technology

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Data Mining, Decision Support, and Data Fusion

Bayesian Inference Approach to Learning Coordinated
Traffic Behavior for Non-tracking Sensors

Lawrence A. Bush1
MIT Lincoln Laboratory

MIT Lincoln Laboratory has developed a method for learning and detecting coordinated traffic behavior for situations in which tracking is infeasible. For example, tracking in large areas with dense traffic is very demanding of sensor resources, and maintaining track of interacting objects is extremely difficult. Therefore, non-tracking methods for interpreting intentional traffic coordination have been explored.

The approach is to statistically model different traffic behavior classes, at a particular location, in order to detect the activity of interest and then combine the results from multiple locations by using a reasoning structure. The seminar will present a method for learning this reasoning structure from the data by using a Bayesian network structure search, then using the Bayesian network to infer the overall situation across multiple sites. This approach emphasizes evidence accumulation and continuous learning, which lend strong support to the proposed multi-input computational framework.

Lincoln Laboratory's research is applied to wide-area persistent surveillance using moving-target indication (MTI) radar data. MTI is a radar data processing technique for detecting moving vehicles. The Laboratory's approach was tested by collecting MTI data while running multiple experimental military ground scenarios, each involving coordinated activity over multiple sites. The overall behavior classes were reliably identified by using this approach.

This seminar will include a tutorial of the related statistical modeling process and Bayesian inference technique. This will be followed by an evaluation of the Laboratory's results, which demonstrate the ability of this technique to identify military activity.

1MS, Computer Science, Rensselaer Polytechnic Institute

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Homeland Protection

Defending Against Biological Terrorism

Dr. Timothy J. Dasey1
MIT Lincoln Laboratory

The intentional use of disease as a weapon has been recorded throughout human history. With modern technology, the potential impact of biological attacks is exceeded by only nuclear weapons. The dramatic advances in the biological sciences in the last few decades and the expertise accumulated in large state-funded offensive biological weapons programs have made the process simpler for those who are inclined to pursue such weapons.

The United States is in the midst of an aggressive research and development program to prevent, detect, and mitigate the effects of biological attacks. Research thrusts include rapid detection and characterization of biological agents for surveillance, response, or forensic purposes. Strategies for organizing and deploying medical resources following an attack are being developed and tested. Improved medicines are needed for prophylactic and therapeutic purposes. Information fusion and data mining techniques are needed to intelligently process diverse datasets for detection and response to an attack. Modeling and simulation of attacks and remedies are used to develop system requirements and designs and to test defensive implementations. Extensive environmental and clinical measurements are needed to understand the performance of technologies and for proper parameterization of simulations.

This seminar will frame the problem by describing the important characteristics of biological weapons, discussing the technical challenges in defending against these weapons and providing examples of the technologies and systems being developed at MIT Lincoln Laboratory to address the problem of biological weapons. The wide breadth of research disciplines in this field will be highlighted.

1PhD, Biomedical Engineering, Rutgers University

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Disease Modeling to Assess Outbreak Detection and Response

Dr. Diane C. Jamrog1 
MIT Lincoln Laboratory

Bioterrorism is a serious threat that has become widely recognized since the anthrax mailings of 2001. In response, one national research activity has been the development of biosensors and networks thereof. A driving factor behind biosensor development is the potential to provide early detection of a biological attack, thereby enabling timely treatment. This presentation introduces a disease progression and treatment model to quantify the potential benefit of early detection. To date, the model has been used to assess responses to inhalation anthrax and smallpox outbreaks.

1PhD, Computation and Applied Mathematics, Rice University

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Solid State Devices, Materials, and Processes

Atomic Physics with a Superconducting Artificial Atom

Dr. William D. Oliver1
MIT Lincoln Laboratory & the Research Laboratory of Electronics

Superconducting persistent-current qubits are quantum-coherent artificial atoms with multiple energy levels. Control sequences comprising harmonic pulses modulate the qubit "transversally" (e.g., Rabi oscillations) and "longitudinally" (e.g., Landau-Zener transitions) to drive transitions between energy levels and probe the atom's coherence.

This seminar presents recent experimental demonstrations of coherence in superconducting artificial atoms under transverse and longitudinal driving conditions. Using a long-lived aluminum qubit (T1=10 µs, T2Echo=23 µs), MIT Lincoln Laboratory performed Rabi, Ramsey, and dynamical decoupling pulse sequences (e.g., spin echo, CP, and CPMG) to probe the coherence and noise generators in our artificial atom as a function of quantization axis [1]. In other experiments with a niobium qubit, the Laboratory demonstrated several examples of large-amplitude longitudinal driving, including Mach-Zehnder-type interferometry of n- photon transistions (n = 1…50) [1]; microwave-induced cooling [2], by which the Laboratory achieved effective qubit temperatures <3 mK; and amplitude spectroscopy [3], a spectroscopy approach that monitors the system response to amplitude rather than frequency. This allowed us to probe the energy spectra of our artificial atom from 0.01–120 GHz, while driving it at a fixed frequency 0.16 GHz. These experiments exhibit a remarkable agreement with theory and are extensible to other solid-state qubit modalities. In addition to our interest in these techniques for fundamental studies of quantum coherence in strongly driven solid-state systems, it is anticipated they will find application to nonadiabatic qubit control and state-preparation methods for quantum information science and technology.

[1] J. Bylander et al., "Noise Spectroscopy through Dynamical Decoupling with a Superconducting Flux Qubit," Nature Physics, vol. 7, pp. 565–570, 2011 (doi:10.1038/nphys1994).
[2] W.D. Oliver et al., "Mach-Zehnder Interferometry in a Strongly Driven Superconducting Qubit," Science, vol. 310, no. 5754, pp. 1653–1657, December 2005.
[3] S.O. Valenzuela et al., "Microwave-Induced Cooling of a Superconducting Qubit," Science, vol. 314, no. 5805, pp. 1589–1592, December 2006.
[4] D.M. Berns et al., "Amplitude Spectroscopy of a Solid-State Artificial Atom," Nature, vol. 455, pp. 51–57, September 2008.

1PhD, Electrical Engineering, Stanford University

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Broad-Spectrum Antiviral Therapeutics

Dr. Todd H. Rider1
MIT Lincoln Laboratory

Currently there are relatively few therapeutics for viruses, and most that do exist are highly pathogen-specific or have other disadvantages. MIT Lincoln Laboratory is developing a broad-spectrum antiviral therapeutic that selectively induces apoptosis in cells containing viral dsRNA, rapidly killing infected cells without harming uninfected cells. Thus far, the Laboratory has shown that its therapeutic is nontoxic and effective against 12 different viruses in 11 mammalian cell types. The Laboratory has also demonstrated that its therapeutic is nontoxic in mice and rescues mice from a lethal H1N1 influenza challenge.

1PhD, Electrical Engineering, Massachusetts Institute of Technology

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Embedded RF Transceiver Design

Dr. Timothy M. Hancock1
MIT Lincoln Laboratory

This seminar discusses the trade-offs and the development of system architectures and component technology for embedded radio-frequency (RF) transceivers. As a system designer and hardware integrator, you are constantly trading off choices between what the algorithm designer would like to have and what can actually be built within a given size, weight, and power constraint. This talk will cover the design and implementation of several RF transceiver systems. These design examples span systems with a bandwidth from less than 1 MHz to greater than 500 MHz. Many of the transceivers discussed rely on commercial off-the-shelf components for building blocks, while one uses a custom Lincoln Laboratory–designed RF integrated circuit. In all cases, a field-programmable gate array is a critical component of the system to provide control of the RF components and of the application and user interface, as well as to implement the MODEM functionality. Design options such as direct sampling, direct conversion, or heterodyne for both transmitters and receivers will be reviewed and, on the basis of a choice of architecture, the impact on the components—such as the RF front-end, filtering, digital-to-analog converter, and analog-to-digital converter—will be discussed.

1Ph.D., Electrical Engineering, University of Michigan

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Fully Depleted Silicon-on-Insulator Process Technology for
Subthreshold-Operation Ultra-Low-Power Electronics

Dr. Jakub Kedzierski1
MIT Lincoln Laboratory

Ultra-low-power transistors are an enabling technology for many proposed applications, including ubiquitous sensor networks, RFID tags, implanted medical devices, portable biosensors, handheld devices, 3D and parallel processing, and space-based applications [1, 2]. Other applications include energy-harvesting devices that recharge batteries by scavenging power from motion or solar cells. With an operating voltage of 0.3 V and an on-current of less than 1 mA/μm, subthreshold transistors use orders of magnitude less power than transistors operated in strong inversion.

MIT Lincoln Laboratory has designed a subthreshold-optimized fabrication process from the substrate material through the interconnect metal. Typical conventional transistors, designed for high performance above threshold operation, will have comparatively high off-state leakage and overlap capacitance, as well as poorer subthreshold slope and potentially lower channel mobility. With the Laboratory transistors specifically engineered for subthreshold operation, it is possible to realize a device with a minimum switching energy and off-state current without significant impact to the energy-delay product. FDSOI ultra-low-power transistors have been fabricated using the Lincoln Laboratory subthreshold-optimized process. A near-ideal subthreshold slope of 64 mV/decade has been demonstrated with longer gate-length transistors (500 nm), with 4 pA/μm of leakage current and a 71% reduction in overlap capacitance. Multiple circuits have been tested below the 0.3 V program goal, with a 97-stage ring oscillator providing baseline characterization. Compared to a commercially available bulk silicon ring oscillator of similar gate length operating at 0.3 V, the subthreshold-optimized FDSOI device decreases the switching energy from 0.241 fJ/μm to 0.099 fJ/μm and decreases the stage delay from 153 ns to 13 ns [3, 4].

[1] D. Bol, R. Ambroise, D. Flandre, J.-D. Legar, "Sub-45 nm Fully-Depleted SOI CMOS Subthreshold Logic for Ultra-Low-Power Applications," 2008 IEEE International SOI Conference Proceedings, pp. 57–58, October 2008.
[2] A. Uchiyama, S. Baba, Y. Nagatomo, J. Ida, "Fully Depleted SOI Technology for Ultra-Low-Power Digital and RF Applications," 2006 IEEE International SOI Conference Proceedings, pp. 15–16, October 2006.
[3] M.J. Deen, S. Naseh, O. Marinov, M.H. Kazemeini, "Very Low-Voltage Operation Capability of Complementary Metal-Oxide-Semiconductor Ring Oscillators and Logic Gates," Journal of Vacuum Science and Technology A, vol. 24, pp. 763–769, 2006.
[4] S.A. Vitale, J. Kedzierski, P.W. Wyatt, M. Renzi, and C.L. Keast, "FDSOI Metal Gate Transistors for Ultra-Low-Power Subthreshold Operation," IEEE International SOI Conference, 11–14 October 2010, IEEE, 2010.

1PhD, Electrical Engineering, University of California–Berkeley

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Geiger-Mode Avalanche Photodiode Arrays for Imaging and Sensing

Dr. Brian F. Aull1
MIT Lincoln Laboratory

This seminar discusses the development of arrays of silicon avalanche photodiodes integrated with digital complementary metal-oxide semiconductor (CMOS) circuits to make focal planes with single-photon sensitivity. The avalanche photodiodes are operated in Geiger mode: they are biased above the avalanche breakdown voltage so that the detection of a single photon leads to a discharge that can directly trigger a digital circuit. The CMOS circuits to which the photodiodes are connected can either time stamp or count the resulting detection events. Applications include three-dimensional imaging using laser radar, wavefront sensing for adaptive optics, and low-light-level imaging.

1PhD, Electrical Engineering, Massachusetts Institute of Technology

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Integrated Optics in Silicon

Dr. Steven J. Spector1, Dr. Michael W. Geis2, and Dr. Theodore M. Lyszczarz3
MIT Lincoln Laboratory

Silicon is an attractive platform for the integration of optical components because of the mature infrastructure dedicated to the fabrication of silicon microelectronic devices. Furthermore, the silicon optical components can be readily integrated with transistors to form complex signal processing systems. At the wavelengths most relevant for optical communication (near 1550 nm), silicon has a high index and low inherent loss, making it an ideal material for compact devices. However, such compact devices also have large scattering loss. In addition, the electro-optic effects are weak in silicon, making it difficult to realize active components. This seminar will describe techniques for fabricating low-loss silicon waveguides, optical filters, low-power silicon PIN diode optical modulators, and high-performance silicon photodiodes using a complementary metal-oxide semiconductor (CMOS) integrated circuit process. The photodiodes exploit ion-implantation damage to create midgap states that enhance sensitivity at the 1550 nm wavelength. These components are being developed for a high-speed optical sampling system that will be used to implement an analog-to-digital converter.

1PhD, Physics, State University of New York–Stony Brook
2PhD, Physics, Rice University
3PhD, Electrical Engineering, Massachusetts Institute of Technology

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Laser-Based Remote Detection of Trace Explosives

Dr. Charles M. Wynn1, Dr. Roderick R. Kunz2, and
Dr. Mordechai Rothschild3
MIT Lincoln Laboratory

The development of a technique with the ability to detect trace quantities of explosives at a distance is of great interest since the detection of such residues can be an indicator for attempts at concealed assembly or transport of explosive materials and devices. In order to be of practical use, the desired detection technique must be rapid and effective from a distance. Measures of effectiveness include high sensitivity to traces of the target compounds and the ability to detect a broad range of explosive materials. Such measures also include low susceptibility to false alarms, a requirement that is often at odds with that of high sensitivity. Several laser-based remote detection methods have been under investigation, including those relying on Raman scattering and laser-induced breakdown spectroscopy.

This seminar describes an alternative approach, which involves ultraviolet photodissociation of condensed-phase material, followed by laser-induced fluorescence of the photofragment nitric oxide. A significant fraction of the photofragment from the dissociation of organo-nitrate explosives is formed in vibrationally excited states. This circumstance is conducive to generating laser-induced fluorescence at wavelengths shorter than the excitation wavelength, thereby significantly reducing the probability of false alarms. Laboratory demonstrations with single laser pulses of several nanoseconds' duration indeed exhibit a high detection efficiency with low false-alarm rates. Further development of this method will require a combination of phenomenological surveys, photochemical studies, and laser engineering.

1PhD, Physics, Clark University
2PhD, Chemistry, University of North Carolina–Chapel Hill
3PhD, Optics, University of Rochester

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Novel Detector Technology for Challenging
Time-Dependent Imaging Applications

Dr. Bernard B. Kosicki1, Dr. Vyshnavi Suntharalingam2, and Dr. James A. Gregory3
MIT Lincoln Laboratory

For most imaging applications, movement in the image is a concern after some exposure time threshold. The Advanced Imaging Technology Group at MIT Lincoln Laboratory has developed three novel imaging devices to handle image motion in different ways. The orthogonal-transfer charge-coupled device (CCD) is designed to image on scenes with continuous translational motions, such as those caused by camera vibration or first-order atmospheric distortions. This device allows exposure times much longer than those allowed by a typical CCD imager, which, to avoid blur, must allow short exposure times. An electronic shutter has been developed for scientific CCDs. The Laboratory has used this shutter to create an imager that captures, and stores in the pixel, several consecutive frames at 500 ns frame intervals while still having high quantum efficiency and low read noise. As a final example, an imager has been developed to record the time of arrival of the first photon to each pixel with time resolution of 250 ps. This imager utilizes a single-photon-sensitive Geiger-mode avalanche-photodiode (APD) array as the light-sensing layer. Each APD is connected to a high-speed digital timing circuit located directly below it. This imager has enabled construction of a flash LADAR system capable of creating three-dimensional images with 5 cm depth resolution.

1PhD, Physics, Harvard University
2PhD, Engineering Science, Pennsylvania State University
3PhD, Materials Science/Metallurgy, Massachusetts Institute of Technology

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Novel Gigapixel Focal Plane for Ground-Based Astronomy
with Atmospheric Distortion Correction*

Dr. Bernard B. Kosicki1 and Dr. Barry E. Burke2
MIT Lincoln Laboratory

The Panoramic Survey Telescope and Rapid Response System (Pan-STARRS) is an innovative wide-field imaging facility developed at the University of Hawaii's Institute for Astronomy.

The combination of four relatively small mirrors (1.8 m) with very large digital cameras (1.4 Gpixels each) results in an economical system that can observe the entire available sky several times each month. The redundancy offered by using multiple mirrors to view the same area of the sky also allows for economical use of not-quite-perfect imager chips.

This seminar describes the technology behind the gigapixel Pan-STARRS charge- coupled device (CCD) focal plane developed and constructed at Lincoln Laboratory. This is the largest focal plane ever constructed for astronomy. A second unique feature is the use of the orthogonal-transfer CCD (OTCCD) as the basic imaging cell for this very large focal plane. This is also the first large-scale use of OTCCD technology, which allows compensation of the translational-movement component of atmospheric distortion. The focal plane design enables atmospheric compensation to be individually implemented for each 10 × 10 arc-minute portion of the total
3-degree-wide image and accounts for the exceptional ability of the system to do very accurate astrometry.

The primary purpose of Pan-STARRS is to detect potentially hazardous objects in the solar system, but its ability to map very large areas of sky to great sensitivity and its ability to find faint moving or variable objects make the system uniquely valuable for a large number of other scientific purposes. The prototype single-mirror telescope PS1 is now operational on Mount Haleakala.

*The MIT Lincoln Laboratory portion of this work was performed under a Collaboration Agreement between MIT Lincoln Laboratory and the University of Hawaii, Institute for Astronomy.

1PhD, Physics, Harvard University
2PhD, Applied Physics, Stanford University

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Optical Sampling for High-Speed, High-Resolution
Analog-to-Digital Conversion

Dr. Paul W. Juodawlkis1and Dr. Jonathan C. Twichell2
MIT Lincoln Laboratory

The performance of digital receivers used in modern radar, communication, and surveillance systems is often limited by the performance of the analog-to-digital converter (ADC) used to digitize the received signal. Optically sampled ADCs, which combine optical sampling with electronic quantization, have been demonstrated to extend the performance of electronic ADCs. The primary advantages of using optics to perform the sampling function include (1) the timing jitter of modern mode-locked lasers is more than an order of magnitude smaller than that of electronic sampling circuitry, (2) the low dispersion of optical components allows picosecond sampling pulses to be used to attain wide analog bandwidth, and (3) demultiplexing to arrays of time-interleaved electronic converters can be performed in the optical domain rather than in the electrical domain with no signal bandwidth, nonlinearity, or memory effect constraints.

MIT Lincoln Laboratory's work in this area has focused on the development of a linear sampling technique referred to as phase-encoded optical sampling. The technique uses a dual-output Mach-Zehnder electro-optic modulator as a sampling transducer to achieve both high linearity and 60 dB suppression of laser amplitude noise. Two-tone tests have been used to demonstrate an intermodulation-free dynamic range of 90 dB. The Laboratory also used optical sampling to directly downsample frequency-modulated chirp signals having 1 GHz bandwidth on an X-band (10 GHz) microwave carrier. The bandwidth of the technique is extended by optically distributing the post-sampling pulses to an array of time-interleaved electronic quantizers. Using high-extinction 1-to-8 LiNbO3 optical time-division demultiplexers to perform the optical distribution, Lincoln Laboratory has demonstrated a 500 MS/s ADC having 10 effective bits of resolution and a spur-free dynamic range in excess of 70 dB.

1PhD, Electrical Engineering, Georgia Institute of Technology
2PhD, Nuclear Engineering, University of Wisconsin–Madison

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Slab-Coupled Optical Waveguide Devices
and Their Applications

Dr. Paul W. Juodawlkis1, Dr. Joseph P. Donnelly2,
Dr. Gary M. Smith3, and Dr. George W. Turner4
MIT Lincoln Laboratory

For the past decade, MIT Lincoln Laboratory has been developing new classes of high-power semiconductor optoelectronic emitters and detectors based on the slab-coupled optical waveguide (SCOW) concept. The key characteristics of the SCOW design include (1) the use of a planar slab waveguide to filter the higher-order transverse modes from a large rib waveguide, (2) low overlap between the optical mode and the active layers, and (3) low excess optical loss. These characteristics enable waveguide devices having large (> 5 × 5 μm) symmetric fundamental-mode operation and long length (~1 cm). These large dimensions, relative to conventional waveguide devices, allow efficient coupling to optical fibers and external optical cavities, and provide reduced electrical and thermal resistances for improved heat dissipation.

This seminar will review the SCOW operating principles and describe applications of the SCOW technology, including Watt-class semiconductor SCOW lasers (SCOWLs) and amplifiers (SCOWAs), monolithic and ring-cavity mode-locked lasers, single-frequency external cavity lasers, and high-current waveguide photodiodes. The SCOW concept has been demonstrated in a variety of material systems at wavelengths including 915, 960–980, 1040, 1300, 1550, and 2100 nm. In addition to single emitters, higher brightness has been obtained by combining arrays of SCOWLs and SCOWAs using wavelength beam-combining and coherent combining techniques. These beam-combined SCOW architectures offer the potential of kilowatt-class, high-efficiency, electrically pumped optical sources.

1PhD, Electrical Engineering, Georgia Institute of Technology

2PhD, Electrical Engineering, Carnegie Mellon University
3PhD, Electrical Engineering, University of Illinois at Urbana-Champaign
4PhD, Electrical Engineering, Johns Hopkins University

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Submicrosecond to Subnanosecond Snapshot Imaging Technology

Dr. Dennis D. Rathman1
MIT Lincoln Laboratory

Research laboratories for both the Department of Defense and the Department of Energy have imaging applications that require very fast snapshot imagers to analyze a wide range of rapidly evolving phenomena. MIT Lincoln Laboratory has a long history of developing high-frame-rate imagers to meet those application needs. This seminar will discuss the most recent technology development of three imagers: a charge-coupled device (CCD)-based 4-exposure device and a CCD-based 50-exposure device that both have burst rates greater than one million frames per second, and a complementary metal-oxide semiconductor (CMOS)-based X-ray imager capable of taking 100 ps snapshot exposures.

1PhD, Physics, Lehigh University

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Three-Dimensional Integration Technology for
Advanced Focal Planes and Integrated Circuits

Dr. Craig L Keast1
MIT Lincoln Laboratory

Over the last several years, MIT Lincoln Laboratory has developed a three-dimensional (3D) circuit integration technology that exploits the advantages of silicon-on-insulator technology to enable wafer-level stacking and micrometer-scale electrical interconnection of fully fabricated circuit wafers [1].

Advanced focal-plane arrays have been the first applications to exploit the benefits of this 3D integration technology because the massively parallel information flow present in two-dimensional imaging arrays maps very nicely into a 3D computational structure as information flows from circuit tier to circuit tier in the z-direction. To date, the Laboratory's 3D integration technology has been used to fabricate four different focal planes, including a two-tier 64 × 64 imager with fully parallel per-pixel analog-to-digital (A/D) conversion [2]; a three-tier 640 × 480 imager consisting of an imaging tier, an A/D conversion tier, and a digital signal processing tier; two-tier 1024 × 1024 pixel, four-side-abuttable imaging modules for tiling large mosaic focal planes [3, 4]; and a three-tier Geiger-mode avalanche photodiode (APD) 3D LIDAR array, using a 30-volt avalanche-photodiode tier, a 3.3-volt complementary metal-oxide semiconductor (CMOS) tier, and a 1.5-volt CMOS tier [5].

Recently, the 3D integration technology has been made available to the circuit-design research community through Multiproject fabrication runs sponsored by the Defense Advanced Research Projects Agency. Two different Multiproject Runs have been completed and included over 60 different circuit designs from 30 different research groups. Three-dimensional circuit concepts explored in these runs included stacked memories, field programmable gate arrays, and mixed-signal and RF circuits. A third Multiproject Run (3DM3) is currently in fabrication. This seminar provides a brief overview of Lincoln Laboratory's 3D-integration process, discusses some of the focal-plane applications in which the technology is being applied, and provides a summary of some of the Multiproject Run circuit results.

[1] J.A. Burns, et al., "A Wafer-Scale 3-D Circuit Integration Technology," IEEE Transactions on Electron Devices, vol. 53, no. 10, pp. 2507–2516, October 2006.
[2] J.A. Burns, et al., "Three-dimensional Integrated Circuits for Low Power, High Bandwidth Systems on a Chip," 2001 ISSCC International Solid-State Circuits Conference, Digest of Technical Papers, vol. 44, pp. 268–269, February 2001.
[3] V. Suntharalingam, et al., "Megapixel CMOS Image Sensor Fabricated in Three-Dimensional Integrated Circuit Technology," 2005 ISSCC International Solid-State Circuits Conference, Digest of Technical Papers, vol. 48, pp. 356–357, February 2005.
[4] V. Suntharalingam, et al., "A Four-Side Tileable, Back Illuminated, 3D- Integrated Megapixel CMOS Image Sensor," IEEE 2009 ISSCC International Solid-State Circuits Conference, Digest of Technical Papers, pp. 38–39, February 2009.
[5] B. Aull, et al., "Laser Radar Imager Based on 3D Integration of Geiger-Mode Avalanche Photodiodes with Two SOI Timing Circuit Layers," 2006 ISSCC International Solid-State Circuits Conference, Digest of Technical Papers, vol. 49, pp. 304–305, February 2006.

1PhD, Electrical Engineering, Massachusetts Institute of Technology

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Toward Large-Scale Trapped-Ion Quantum Processing

Dr. John Chiaverini1
MIT Lincoln Laboratory

Atomic ions held in electromagnetic traps and manipulated with optical, radio-frequency, and microwave fields are among the most promising implementations for useful quantum information processing. These well-isolated quantum two-level systems (qubits) have been shown to maintain coherence for many seconds while also being controllable on the microsecond timescale. Accomplishments at the few-qubit level include high-fidelity demonstrations of basic quantum algorithms, but a clear path to a large-scale processor is not fully defined. Current work involves devising and demonstrating scalable architectures and low-error quantum operations. This presentation will describe efforts to develop scalable ion techniques, in particular rapid ion-qubit loading, integration of technology for increased on-chip control of ion qubits, and the reduction of multi-qubit gate errors. By using a novel ion-loading method employing cold neutral atoms, we plan to increase array loading rates by orders of magnitude, approaching the required rates for realistic computations. Through the use of a surface-electrode trap geometry, efficient measurement and ion routing devices may be integrated directly with trapping electrodes for simpler scaling. Additionally, utilizing novel electrode preparation and materials that include superconducting technologies, we investigate trap electrode surface properties to address anomalous ion heating, which may soon limit standard two-qubit gate operations.

1PhD, Physics, Stanford University

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Space Control Technology

Advances in Precision Orbit Determination

Dr. Steven M. Hunt1
MIT Lincoln Laboratory

The U.S. military puts significant resources into tracking U.S. spacecraft, foreign space systems, and orbital debris. Knowing the location and orbital motion of space objects is a key component of space situational awareness (SSA), coupled with measures to ascertain the purpose and function of these objects. The ability to incorporate sensor measurements into precision orbits is critical to a robust SSA capability; reliably propagating orbits into the future is necessary to enable timely warning of potential threats to U.S. space systems. This seminar provides an overview of the physics and the state of the art in precision orbit determination, including recent advances accomplished at MIT Lincoln Laboratory. Several measurement examples are given of the potential accuracies that can be achieved in both orbit determination and propagation.

1PhD, Electrical Engineering, Boston University

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Integrated Optomechanical Analysis of Terrestrial,
Airborne, and Spaceborne Sensors

Dr. Keith B. Doyle1
MIT Lincoln Laboratory

MIT Lincoln Laboratory has developed an array of sensors ranging from ground and ship-based radar antennas to airborne and spaceborne free-space laser communication terminals, missile and countermeasure payloads, infrared airborne systems, and satellite space sensors. These high-performance systems must perform and survive in harsh environments while meeting strict pointing and imaging requirements subject to temperature, inertial, vibrations, and shock loads.

This seminar provides an overview of the optomechanical analysis process that couples computer-aided design (CAD), thermal, structures, controls, and optical design tools, enabling system performance to be evaluated as a function of environmental disturbances and mechanical design variables. Examples discussed include ground-based sensors that operate subject to the effects of gravity and temperature variations; airborne sensors that operate subject to acoustic, aerodynamic, and aircraft vibrations; and spaceborne systems that must survive launch and operate subject to both thermal variations on orbit and spacecraft dynamic disturbances.

1PhD, Mechanical Engineering, University of Arizona

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Predicting and Avoiding Close Approaches and Potential
Collisions in Geosynchronous Orbits

Dr. Richard I. Abbot1 and Miquela C. Vigil2
MIT Lincoln Laboratory

The geosynchronous orbit regime is getting crowded with over 300 active, revenue-producing large satellites and over 600 inactive resident space objects that pose a physical collision threat to the active satellites. The in situ demise of a particular satellite, Telstar 401 initiated a research and development effort at MIT Lincoln Laboratory to address this threat. This work, which is done in collaboration with commercial satellite operators, is accomplished using the mechanism of Cooperative Research and Development Agreements. Initial work to detect and warn of close approaches with failed satellites led to more extensive research on the collision threat, as well as on how to monitor it over the entire geosynchronous belt and how to develop avoidance strategies to prevent collisions. It has been found that
  1. There is a significant probability of collision;
  2. The continuing failure of geosynchronous satellites and injection of rocket bodies into or near geosynchronous orbit will increase the threat;
  3. Collision avoidance strategies can be developed that require no additional expenditure of valuable station-keeping fuel; and
  4. Non-geosynchronous debris that can cross geosynchronous orbits poses another significant problem that has to be addressed.

This seminar surveys what has been achieved so far in predicting the threat and protecting satellites. An assessment of the probability of collision is presented, as well as a description of the close conjunction monitoring and warning system that have been developed.

1PhD, Physics/Meteorology, University of Texas–Austin
2MS, Earth, Atmospheric, & Planetary Sciences, Massachusetts Institute of Technology

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Retrieval of Atmospheric Temperature and Moisture Profiles from Hyperspectral Sounding Data Using a Projected Principal
Components Transform and a Neural Network

Dr. William J. Blackwell1
MIT Lincoln Laboratory

A novel statistical method for the retrieval of atmospheric temperature and moisture (relative humidity) profiles has been developed and evaluated with simulated clear-air hyperspectral sounding data. The accuracies of the estimates produced by the algorithm meet or exceed (in some cases by a factor of two) the accuracies of the estimates from traditional iterated minimum variance retrieval techniques while requiring less computation. The algorithm is implemented in two stages. First, a projected principal components (PPC) transform is used to reduce the dimensionality of and optimally extract geophysical profile information from the spectral radiance data. Second, an artificial feedforward neural network (NN) is used to estimate the desired geophysical parameters from the projected principal components.

The performance of this method (henceforth referred to as the PPC/NN method) was evaluated by using simulated clear-air observations from the 2378-channel Atmospheric Infrared Sounder. Separate training and validation profile data were selected from the NOAA88b radiosonde set of approximately 7500 profiles. Surface, solar, and instrument effects were modeled.

It was found that the PPC/NN method has a number of advantages over traditional statistical and physical/iterative hyperspectral profile retrieval techniques. Neural-network estimates based on the PPC transform were significantly more accurate than neural-network estimates obtained with conventional principal components techniques, including the Karhunen-Loeve transform and the noise-adjusted principal components transform. The retrieval accuracy of PPC/NN was also superior to that of a principal components regression technique.

One particularly noteworthy result of the current work is a comparative study between the PPC/NN method and an iterated minimum-variance (IMV) method. The temperature profile retrieval accuracy of both methods is similar, but the relative humidity profile retrieval accuracy of PPC/NN was greater than that of the IMV method at all altitudes and substantially better near the surface.

1PhD, Electrical Engineering, Massachusetts Institute of Technology

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Communication Systems and Cyber Security

Building a High-Capacity Internet Protocol Airborne Backbone
with Disparate Radio Technologies

Dr. Bow-Nan Cheng1
MIT Lincoln Laboratory

The current generation of long-range, high-capacity military radios are stovepiped systems that lack interoperability—each radio provides a subset of disparate link information in nonstandard interfaces—and have built-in homegrown or industry-based routers running nonstandard, proprietary routing protocols. The issue is complicated further in that airborne link characteristics change rapidly, often requiring direct link layer feedback from the radio to make routing decisions. This seminar will present the technology overview for current and emerging radio-to-router interface technology as well as practical design and implementation of these technologies in an airborne network with various radio technologies. Results and experience from emulations and field tests with the goal of designing, developing, and prototyping a high-capacity airborne Internet protocol (IP) backbone are presented.

1PhD, Computer Science, Rensselaer Polytechnic Institute

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Challenges in Computer Security Experiments

Dr. Charles V. Wright1
MIT Lincoln Laboratory

Rigorous scientific experimentation in system and network security remains an elusive goal, especially when dealing with client-side threats and defenses, where user input is often required as part of the experiment. This seminar covers some of the unique research challenges in applying the scientific method to security and presents recent techniques for performing more realistic experiments on isolated test bed networks. Specifically presented is an approach for generating realistic client-side workloads and for creating reasonable facsimiles of remotely hosted applications like the Web. Approaches for low-artifact instrumentation of computer systems are also discussed.

1PhD, Computer Science, Johns Hopkins University

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Cooperative Communication in Heterogeneous Wireless Networks

Dr. Brooke E. Shrader1
MIT Lincoln Laboratory

Cooperative communication techniques, in which users relay for other users in order to improve performance, are typically explored in wireless networks consisting of homogeneous nodes, such as sensor networks or vehicular ad hoc networks. Future wireless networks will consist of a blend of different types of nodes, including satellite, airborne, and terrestrial nodes, with widely varying characteristics in terms of achievable data rate, loss rate, and propagation time. This seminar will include a tutorial and focus on recent research in cooperative capabilities and techniques, including the use of network coding, for heterogeneous wireless networks.

1PhD, Electrical Engineering, University of Maryland

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Dynamic Link Adaptation for Satellite Communications

Dr. Huan Yao1
MIT Lincoln Laboratory

Future protected military satellite communications will continue to use high transmission frequencies to capitalize on the large amounts of available bandwidth. However, the data flowing through these satellites will transition from the circuit-switched traffic of today's satellite systems to Internet-like packet traffic. One of the main differences in migrating to packet-switched communications is that the traffic will become bursty (i.e., the data rate from particular users will not be constant). The variation in data rate is only one of the potential system variations. At the frequencies of interest, rain and other weather phenomena can introduce significant path attenuation for relatively short time periods. Current protected satellite communications systems are designed with sufficient link margins to provide a desired availability under such degraded path conditions. These systems do not have provisions to use the excess link margins for additional capacity when weather conditions are good. The focus of this seminar is the design of a future satellite system that autonomously reacts to changes in link conditions and offered traffic. This automatic adaptation drastically improves the overall system capacity and the service that can be provided to ground terminals.

1PhD, Electrical Engineering, Massachusetts Institute of Technology

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EMBER: A Global Perspective on Extreme Malicious Behavior

Tamara H. Yu1, Dr. Richard P. Lippmann2,
Dr. James F. Riordan3, and Stephen W. Boyer4
MIT Lincoln Laboratory

Geographical displays are commonly used for visualizing widespread malicious behavior of Internet hosts. Placing dots on a world map or coloring regions by the magnitude of activity often results in cluttered maps that invariably emphasize population-dense metropolitan areas in developed countries where Internet connectivity is highest. To uncover atypical regions, it is necessary to normalize activity by the local computer population.

This seminar presents EMBER (Extreme Malicious Behavior viewER), an analysis and display of malicious activity at the city level. EMBER uses a metric called Standardized Incidence Rate (SIR) that is the number of hosts exhibiting malicious behavior per 100,000 available hosts. This metric relies on available data that (1) maps IP addresses to geographic locations, (2) provides current city populations, and (3) provides computer usage penetration rates. Analysis of several months of suspicious source IPs from DShield identifies cities with extremely high and low malicious activity rates on a day-by-day basis. In general, cities in a few Eastern European countries have the highest SIRs, whereas cities in Japan and South Korea have the lowest. Many of these results are consistent with news reports describing local cyber security policies. The distribution of SIRs for cities with comparable population levels has a long tail similar to a power law. This suggests that malware preferentially spreads to regions with currently high levels of malicious activity, as suggested by analysis of many malware executables in the past.

1MEng, Electrical Engineering and Computer Science, Massachusetts Institute of Technology
2PhD, Electrical Engineering and Computer Science, Massachusetts Institute of Technology
3PhD, Computational Mathematics, University of Minnesota
4MS, Engineering and Management, Massachusetts Institute of Technology

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Experiences in Cyber Security Education:
The MIT Lincoln Laboratory Capture-the-Flag Exercise

Joseph M. Werther1 , Michael A. Zhivich2, and Timothy R. Leek3
MIT Lincoln Laboratory

Dr. Nickolai Zeldovich4
MIT Computer Science and Artificial Intelligence Laboratory

Many popular and well-established cyber security capture-the-flag (CTF) exercises are held each year at a variety of settings, including universities and semiprofessional security conferences. The CTF format also varies greatly, ranging from linear puzzle-like challenges to team-based offensive and defensive free-for-all hacking competitions. While these events are exciting and important as contests of skill, they offer limited educational opportunities. In particular, since participation requires considerable a priori domain knowledge and practical computer security expertise, the majority of typical computer science students are excluded from taking part in these events. The goal in designing and running the MIT Lincoln Laboratory CTF was to make the experience accessible to a wider community by providing an environment that would not only test and challenge the computer security skills of the participants but also educate and prepare those without extensive prior expertise. This seminar presents the Laboratory's self-consciously educational and open CTF, including discussions of our teaching methods, game design, scoring measures, logged data, and lessons learned.

1MEng, Computer Systems Engineering, Rensselaer Polytechnic Institute
2MEng, Electrical Engineering and Computer Science, Massachusetts Institute of Technology
3MS, Computer Science, University of California–San Diego
4PhD, Computer Science, Stanford University

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Free-Space Laser Communications

Dr. Frederick G. Walther1
MIT Lincoln Laboratory

Laser communications (lasercom) provides significant advantages, compared to radio-frequency (RF) communications, which include a large, unregulated bandwidth and high beam directionality for free-space links. These advantages provide capabilities for high (multi Gb/s) data transfer rates; reduced terminal size, weight and power; and a degree of physical link security against out-of-beam interferers or detectors. This seminar addresses the key components of lasercom system design, including modeling and simulation of atmospheric effects, link budget development, employment of spatial and temporal diversity techniques to mitigate signal fading due to scintillation, and requirements for acquisition and tracking system performance.

1PhD, Physics, Massachusetts Institute of Technology

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Implementation Considerations for Wideband Wireless Communications

Dr. Nancy B. List1
MIT Lincoln Laboratory

Unexpected technical challenges often arise in the process of transferring technology from theory into practical applications. It is well known that modulator distortion causes problems for the transmission of communications signals. Less obvious, however, is the effect of modulator distortion on signals used for time tracking in wireless systems requiring strict timing control. Narrowband tracking signals are often used to synchronize systems transmitting wideband communications signals. While narrowband tracking signals may be less sensitive than communications signals to many types of distortion, they are particularly sensitive to group delay variation. As a result, relatively small levels of group delay variation across the frequency band can cause unexpected overall system degradation. This seminar will describe the real-world challenges of time-tracking in frequency-hopped satellite communications systems transmitting signals at high data rates, as well as practical methods to analyze and overcome these challenges.

1PhD, Electrical Engineering, Georgia Institute of Technology

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Laser Communications Transceiver Design

Dr. David O. Caplan1
MIT Lincoln Laboratory

Optical communications has provided unprecedented capacity in modern networks and has fueled the rapid growth of the Internet. Until recently, the sensitivity and efficiency of optical transmitters and receivers have not been driving factors in the buildup of fiber-optical networks. But as the demand for bandwidth approaches the limitations of current communication systems, more sensitive receivers can provide a means for improving optical network performance in terms of both power and bandwidth efficiency. High-sensitivity receivers can also reduce mid-span amplifier requirements, can extend link distances, and are especially beneficial for free-space optical communications, since improvements in receiver sensitivity directly reduce transmitted power requirements.

This seminar will provide an overview of optical transmitter and receiver designs, from relatively simple direct detection systems used in short terrestrial fiber-optic links to sophisticated near quantum-limited systems suitable for deep-space-based optical links. The basic characteristics of optical sources, modulators, amplifiers, detectors, and associated noise sources will be discussed along with some of the unique properties that distinguish optical communication systems and components from their radio-frequency (RF) counterparts. Also presented will be practical trade-offs and implementation issues that arise from using various technologies, modulation formats, and coding in both free-space and fiber-optic links.

1PhD, Electrical Engineering, Northwestern University

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New Approaches to Automatic Speaker Recognition
and Forensic Considerations

Dr. Joseph P. Campbell1 and Dr. Pedro A. Torres-Carrasquillo2
MIT Lincoln Laboratory

The area of automatic speaker recognition has been dominated by systems using only short-term, low-level acoustic information, such as cepstrall features. While these systems have produced reasonably low error rates, they ignore other levels of information beyond low-level acoustics that convey speaker information. This seminar will cover recent research on methods that exploit high-level information. For example, idiosyncratic word usage and pronunciation are high-level features that can be exploited. Furthermore, these high-level features can be combined with conventional features for increased accuracy. New compensation methods will also be covered that increase robustness due to degrading factors common to the forensic domain. The seminar concludes with appropriate uses of this technology, especially cautions regarding forensic-style applications, and looking at its future directions.

1PhD, Electrical Engineering, Oklahoma State University
2PhD, Electrical Engineering, Michigan State University

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Quality of Service and Cross-Layer Optimization for
Satellite Communications Networks

Dr. Jeffrey S. Wysocarski1
MIT Lincoln Laboratory

To efficiently utilize limited radio-frequency (RF) resources, future packet-switched satellite networks will dynamically allocate resources on the uplink and downlink. Designing the resource-allocation algorithms to maximize link-layer efficiency is insufficient. The resource-allocation algorithms must work cooperatively with the network layer and transport layer to optimize network layer performance and provide quality of service (QoS) to applications and users. Several mechanisms for facilitating this required cooperation between the layers are presented. The individual roles and actions of the layers as well as their interaction are defined. Router QoS schedulers that continue to provide service differentiation in the presence of link variations are illustrated, and downlink scheduling architectures that provide terminal QoS guarantees are demonstrated. Finally, the interaction between the transmission control protocol (TCP) and the dynamic resource-allocation algorithms is investigated, leading to suggested modifications of either the resource-allocation algorithms, the TCP protocol, or both.

1PhD, Electrical Engineering, Clemson University

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Reliability in Large Wireless Communications Networks

Dr. Linda M. Zeger1
MIT Lincoln Laboratory

Large wireless networks are subject to packet losses on individual links, yet the demand for them to carry increasingly greater amounts of data, such as images, to more users is increasing. New techniques for efficient delivery of sizable files to a large number of users are presented for reliable and best-effort delivery in lossy channels.

In addition to packet losses, large wireless networks can be subject to failure of individual nodes or individual links, as well as power shortages, caused by accidents, malfunctions, disasters, weather, or deliberate attacks. Recovery mechanisms are introduced to ensure not only that there is connectivity across the network, but also that more than a minimal data rate can be carried across the network.

1PhD, Physics, Harvard University

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Robust Multi-user Wireless Communications

Dr. Thomas C. Royster IV1
MIT Lincoln Laboratory

Many of today's wireless communications systems continue to push toward higher data rates to support diverse user applications. Users that must communicate under adverse conditions, however, place a premium on robustness and security. This seminar discusses physical layer and medium-access control layer techniques for designing resiliency into wireless communication systems. Trade-offs among data rate, robustness, delay, and complexity are described. Also discussed are ways in which continuing advances in digital processing enable fresh design approaches for robust systems.

1PhD, Electrical Engineering, Clemson University

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Superconducting NbN Nanowire Single-Photon Detectors

Dr. Andrew J. Kerman1
MIT Lincoln Laboratory

In this seminar, ongoing work on single-photon detectors based on superconducting niobium-nitride (NbN) nanowires will be discussed. These nanometer-scale devices exploit the ultrafast nonequilibrium electronic photo-response in ultrathin films of the highly disordered superconductor NbN to produce a photon counter of unprecedented speed and sensitivity. With better than 30 ps timing resolution, ~few ns reset time after a detection, and high detection efficiency (>85% demonstrated at 1550 nm), these devices show promise as an enabling technology in a number of areas, such as high-data-rate interplanetary optical communications, spectroscopy of ultrafast quantum phenomena in biological and solid-state physics, quantum key distribution and quantum computation, astrophysics, laser radar, and high-speed noninvasive digital circuit testing.

1PhD, Physics, Stanford University

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Technical Considerations for Mitigating
Interference in Satellite Communications

Dr. Dean Kolba1
MIT Lincoln Laboratory

As the dependence on satellite communications continues to grow, so does the need for interference-mitigating technologies. This seminar discusses the options for increasing the interference resistance of satellites and ground terminals. Techniques such as bandwidth spreading, antenna discrimination, onboard processing, and routing are all investigated. Generalized analysis for notional scenarios is also examined.

1PhD, Electrical Engineering, Rice University

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Waveform Design for Airborne Networks

Dr. Frederick J. Block1
MIT Lincoln Laboratory

Airborne networks are expected to play a significant role in future military communications. Successful deployment of these ad hoc networks requires overcoming many unique challenges. For example, nodes are often separated by great distances and can be highly mobile. In addition to multiple-access interference from other radios in the network, interference from jammers located over a wide geographic region may be able to reach a receiver because of its high altitude. The seminar gives an overview of channel models for airborne networks and examines the trade-offs that must be made when choosing the modulation, coding, channel access, and routing techniques.

1PhD, Electrical Engineering, Clemson University

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Optical Propagation and Technology

Mechanical Systems Engineering of Optical Sensors

Dr. Steven E. Forman1 
MIT Lincoln Laboratory

During the past 20 years, MIT Lincoln Laboratory has developed several different optical sensor experiments that have flown on airborne and space platforms. These include the Space-Based Visible, Airborne Infrared Imager, and Advanced Land Imager. Each represents a one-of-a-kind sensor fully engineered at the Laboratory. This seminar summarizes several of the mechanical systems engineering areas and issues that occurred throughout design, analysis, fabrication, integration, and testing of these systems. Included are discussions of optical, optomechanical, structural, and thermal engineering; electronic packaging; mechanism design; focal-plane packaging; control-system engineering; materials selection and testing; environmental testing; failure analysis; and computer-aided-design and analysis tools.

1PhD, Mechanical Engineering, Harvard University

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Radar and Signal Processing

Analysis of Track Association Error with
Multiple-Input Multiple-Output Radar

Dr. Shawn Kraut1 and Dr. Daniel W. Bliss2
MIT Lincoln Laboratory

This seminar will present a methodology for evaluating tracking association performance and applying it to multiple-input multiple-output (MIMO) radar. One argument for MIMO radar over traditional ground moving target indicator (GMTI) radar is that it can lead to improved contact-to-track association performance. In this work, MIT Lincoln Laboratory developed a methodology for efficiently evaluating this claim, quantifying the dependence on system parameters such as aperture and coherent processing interval. Two general factors affecting track association are included: measurement uncertainty and track-update latency. Both factors are impacted by a MIMO radar: first, a MIMO operating mode can decrease the measurement error, in both Doppler and azimuth; second, it can increase detection probability (due to enhanced discrimination of slow-moving targets from the clutter ridge), reducing the average latency between track updates. The methodology can aid a design engineer in quantitatively evaluating the decrease in the probability of a track association error with a MIMO radar in lieu of running multiple tracking simulations. In this way, one can quickly assess the design trades of system parameters.

1PhD, Physics, University of Colorado–Boulder
2PhD, Physics, University of California–San Diego

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Anticipatory Medical Monitoring: With Applications to Epileptic Seizure
and Premature-Infant Sleep-Apnea Prediction

Dr. Daniel W. Bliss1, Dr. James R. Williamson2, and Dr. David W. Browne3
MIT Lincoln Laboratory

Advanced statistical signal processing and machine-learning techniques enable the prediction of a variety of medical distress events by detecting distress precursors. The techniques can potentially identify medical states that cannot be identified by using traditional signal or image observation approaches. For some types of medical distress events, there are precursors that cannot be observed directly but can be extracted in a statistical sense. Using these approaches represents a fundamental shift in the evaluation of data by the medical community. Subtle statistical properties can sometimes be extracted by using arrays of homogeneous and heterogeneous sensors. An important aspect of the statistical signal processing approach is to construct feature vectors that capture the essential ingredients of the detection problem. As examples, these feature vectors may include components from eigenvalue distributions of space-delay correlation matrices, or the estimated mutual information of various observed signals.

In this seminar, we present statistical signal processing approaches for predicting epileptic seizures and premature-infant sleep apnea. In both cases, the algorithms are exercised on experimental data. Specifically, for seizure prediction, we demonstrate the ability to detect seizure precursors with relatively high reliability. In addition, we discuss potential interpretations of the feature vector data. For premature-infant sleep apnea, we discuss the development of mutual information and entropic techniques to construct feature vectors. For both prediction applications, we employ a support vector machine to evaluate the implications of an observed feature vector.

1PhD, Physics, University of California–San Diego
2PhD, Cognitive and Neural Systems, Boston University
3PhD, Electrical Engineering, University of California–Los Angeles

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Covariance Matrix Estimation Bounds

Dr. Steven T. Smith1 
MIT Lincoln Laboratory

Algorithms and systems analysis for signal detection, location, and classification all rely on covariance-based methods. But how well understood is the important problem of covariance matrix estimation? What does "accuracy" mean in the context of covariance matrices? This talk addresses these questions at their deepest level and provides powerful new tools and insights, as well as well as some startling surprises. The covariance matrix problem is framed as an intrinsic estimation problem on the space of positive definite (covariance) matrices, which has the structure of a homogeneous or quotient space, not a vector space—the necessary setting for classical Cramér-Rao bounds. Covariance matrix estimation accuracy bounds are derived from an intrinsic derivation of the Cramér-Rao bound on arbitrary Riemannian manifolds (another new development) and compared to the accuracy achieved by standard methods involving the sample covariance matrix (SCM). Estimator efficiency is discussed from different, novel viewpoints. Remarkably, it is shown that that from an intrinsic perspective, the SCM is a biased and inefficient estimator; the bias corresponds to the SCM's poor estimation quality at low sample support—this contradicts the well-known fact that E[SCM] = R because the linear expectation operator implicitly treats the covariance matrices as points in a real vector space, compared to the intrinsic treatment of positive-definite Hermitian matrices used in this talk. The accuracy bound on unbiased covariance matrix estimators is shown to be about (10/log10)*n/sqrt(K) decibels, where n is the matrix order and K is the sample support. Thus, a connection is established between estimation loss for covariance matrices and the well-known Reed-Mallett-Brennan detection loss in adaptive filtering problems. Simple closed-form expressions for all results are presented and compared to numerical evidence based on Monte Carlo simulations. The analysis approach developed is directly applicable to many other estimation problems on manifolds encountered in signal processing and elsewhere, such as estimating rotation matrices in computer vision and estimating subspace basis vectors in blind source separation. Finally, several intriguing open questions pertaining to the possibility of improved covariance matrix estimation methods at low sample support are presented.

1 PhD, Mathematics, Harvard University

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Detection, Estimation, and Beamforming for Adaptive Sensor Arrays: Algorithms and Performance

Dr. Christ D. Richmond1 
MIT Lincoln Laboratory

Over the past 40 years, a class of adaptive detection and estimation algorithms has emerged that exploits the spatial and temporal diversity available from sensor array systems in order to provide robust signal detection and parameter estimation under rather adverse/nonideal conditions. These arrays are often deployed in high multipath environments plagued by limiting interference with unknown statistics. A uniformly most powerful test does not exist for this class of problems. Consequently, optimal detection and estimation rely heavily upon maximum-likelihood (ML) estimates of unknown parameters including use of the data sample covariance matrix. Analyses embracing practicalities such as finite sample support, array response uncertainty/mismatch, nonstationarity, and nonlinear parameter estimation are quintessential for the design of systems requiring precision and robustness, e.g., adaptive radar and sonar systems.

This seminar presents an overview analysis of this class of adaptive algorithms addressing the aforementioned issues of practical interest via the use of random matrix theory. Specifically, the receiver operation characteristics are considered for the detector class that includes the adaptive matched filter, Kelly/Khatri’s generalized likelihood ratio test, Conte/Scharf’s adaptive coherence estimator, and the two-dimensional adaptive sidelobe blanker. The mean squared error (MSE) performance of the signal parameter estimation class that includes the nonlinear ML estimator and the Capon-minimum variance distortionless response beamformer/estimator often used for frequency and/or angle estimation is considered. The MSE performance is considered below threshold where local error performance bounds, like the Cramér-Rao bound, are not useful. Lastly, some discussion of robust sample covariance-based adaptive beamforming is provided, and new results and insights on the statistical relationships between conventional and adaptive processing are presented.

1PhD, Electrical Engineering, Massachusetts Institute of Technology

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Improving Ad Hoc Wireless Networks:  
Bounds, Optimization, Multiple-Input Multiple-Output,
and Interference Mitigation

Dr. Daniel W. Bliss1
MIT Lincoln Laboratory

There are numerous interesting theoretical and practical concerns for ad hoc wireless networks. Current ad hoc wireless network implementations are relatively fragile and inefficient. The principal limitation is spatial-spectral reuse. A typical network employs a carrier-sense approach to avoid collisions. Because of the hidden node or hidden terminal problem, the carrier-sense threshold must be very conservative; consequently, the resources are used inefficiently. By employing multiple-input multiple-output (MIMO) links, wireless networks can improve robustness and enable higher data rates. This improvement is of even greater value if the MIMO receiver can mitigate interference. Potentially, with the ability to mitigate interference, network throughput can be improved by allowing links to operate in the presence of other links. Actual link performance is sensitive to the particular channel and interference environment, receiver approach, and space-time code. Network performance is sensitive to node density, physical layer design, and network protocol.

In this seminar, a number of MIMO wireless network topics are discussed. An introduction to adaptive array processing, MIMO communication, and wireless networking is provided. Approaches for bounding and optimizing network performance given nodes with multiple-antenna systems are presented. In particular, an approach to optimize spectral efficiency to minimize hidden-node interference is introduced. Theoretical performance bounds of MIMO networks that employ interference mitigation are presented; this includes a discussion of the optimal transmit covariance matrix rank for a given network density. As time permits, a survey of related advanced protocol and advanced MIMO techniques is discussed.

1PhD, Physics, University of California–San Diego

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Multicore Programming in pMatlab® Using Distributed Arrays

Dr. Jeremy Kepner1
MIT Lincoln Laboratory

MATLAB is one of the most commonly used languages for scientific computing, with approximately one million users worldwide. Many of the programs written in MATLAB can benefit from the increased performance offered by multicore processors and parallel computing clusters. The MIT Lincoln Laboratory pMatlab library (http://www.ll.mit.edu/pMatlab) allows high-performance parallel programs to be written quickly by using the distributed arrays programming paradigm. This talk provides an introduction to distributed arrays programming and will describe the best programming practices for using distributed arrays to produce programs that perform well on multicore processors and parallel computing clusters. These practices include understanding the concepts of parallel concurrency versus parallel data locality, using Amdahl's Law, and employing a well-defined design-code-debug-test process for parallel codes.

1PhD, Physics, Princeton University

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Phased-Array Processing and Multiple-Input
Multiple-Output Radars

Dr. Vito F. Mecca1
MIT Lincoln Laboratory

Phased-array radar systems are a more flexible alternative to traditional single-element dish radar systems. Phased arrays operate by applying a different delay—or phase shift—to signals at each element of the array. This process effectively focuses or "steers" the radar's spatial beam response and can be performed on both signal transmission and reception. Continuing advances in computational capacity and hardware design have allowed for complete digital reception of multiple simultaneous beams and subsequent digital processing. However, radar systems capable of simultaneously transmitting multiple, different, coded waveforms from each transmit element have been unavailable in the past.

This seminar introduces a class of multiple-input multiple-output (MIMO) radars that are capable of emitting different signals from each transmitter element. In this introductory-level seminar, the fundamental concepts behind phased-array and MIMO radar techniques are explained in terms of real-world scenarios in which MIMO operation would be advantageous. The advanced MIMO techniques developed at MIT Lincoln Laboratory for joint transmit and receive array processing are presented in conjunction with data results.


1PhD, Electrical and Computer Engineering, Duke University

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Polynomial Rooting Techniques for Adaptive Array Direction Finding

Dr. Gary F. Hatke1 
MIT Lincoln Laboratory

Array processing has many applications in modern communications, radar, and sonar systems. Array processing is used when a signal in space, be it electromagnetic or acoustic, has some spatial coherence properties that can be exploited (such as far-field plane wave properties). The array can be used to sense the orientation of the plane wave and thus deduce the angular direction to the source. Adaptive array processing is used when there exists an environment of many signals from unknown directions as well as noise with unknown spatial distribution. Under these circumstances, classical Fourier analysis of the spatial correlations from an array data snapshot (the data seen at one instance in time) is insufficient to localize the signal sources.

In estimating the signal directions, most adaptive algorithms require computing an optimization metric over all possible source directions and searching for a maximum. When the array is multidimensional (e.g., planar), this search can become computationally expensive, as the source direction parameters are now also multidimensional. In the special case of one-dimensional (line) arrays, this search procedure can be replaced by solving a polynomial equation, where the roots of the polynomial correspond to estimates of the signal directions. This technique had not been extended to multidimensional arrays because these arrays naturally generated a polynomial in multiple variables, which does not have discrete roots.

This seminar introduces a method for generalizing the rooting technique to multidimensional arrays by generating multiple optimization polynomials corresponding to the source estimation problem and finding a set of simultaneous solutions to these equations, which contain source location information. It is shown that the variance of this new class of estimators is equal to that of the search techniques they supplant. In addition, for sources spaced more closely than a Rayleigh beamwidth, the resolution properties of the new polynomial algorithms are shown to be better than those of the search technique algorithms.

1PhD, Electrical Engineering, Princeton University

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Synthetic Aperture Radar

Dr. Gerald R. Benitz1 
MIT Lincoln Laboratory

MIT Lincoln Laboratory is investigating the application of phased-array technology to improve the state of the art in radar surveillance. Synthetic aperture radar (SAR) imaging is one mode that can benefit from a multiple-phase-center antenna. The potential benefits are protection against interference, improved area rate and resolution, and multiple simultaneous modes of operation.

This seminar begins with an overview of SAR, giving the basics of resolution, collection modes, and image formation. Several imaging examples are provided. Results from the Lincoln Multimission ISR Testbed (LiMIT) X-band airborne radar are presented. LiMIT employs an eight-channel phased-array antenna and records 180 MHz bandwidth from each channel simultaneously. One result employs adaptive processing to reject wideband interference, demonstrating recovery of a corrupted SAR image. Another result employs multiple simultaneous beams to increase the area of the image beyond the conventional limitation that is due to the pulse repetition frequency. Areas that are Doppler ambiguous can be disambiguated by using the phased-array antenna.

1PhD, Electrical Engineering, University of Wisconsin–Madison

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Systems and Architecture

Choices, Choices, Choices (Decisions, Decisions, Decisions)

Dr. Robert T. Shin1
MIT Lincoln Laboratory

As you plan a career after graduating from a university of college, you are faced with many choices and decisions, not just now but for many and your most productive years. While there generally is not a right or wrong decision, it is helpful to think about and make these decisions in a more systematic way. This seminar looks at perspectives on how one might think about making a choice and making an impact, especially as an architect of future advanced systems. Also, my lessons learned along the way, in architectural thinking and in management, are presented in the hope that you might find them useful as you advance in your careers. Finally, a short overview of MIT Lincoln Laboratory, a federally funded research and development center, is presented as a case study on how one can leverage such an organization to make an impact.

1PhD, Electrical Engineering, Massachusetts Institute of Technology


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