Publications
Application of the Fornasini-Marchesini first model to data collected on a complex target model
June 4, 2014
Conference Paper
Published in:
ACC 2014: American Control Conf., 4-6 June 2014.
Summary
This work describes the computation of scatterers that lay on the body of a real target which are depicted in radar images. A novelty of the approach is the target echoes collected by the radar are formulated into the first Fornasini-Marchesini (F-M) state space model to compute poles that give rise to the scatterer locations in the two-dimensional (2-D) space. Singular value decomposition carried out on the data provides state matrices that capture the dynamics of the target. Furthermore, eigenvalues computed from the state transition matrices provide range and cross-range locations of the scatterers that exhibit the target silhouette in 2-D space. The maximum likelihood function is formulated with the state matrices to obtain an iterative expression for the Fisher information matrix (FIM) from which posterior Cramer-Rao bounds associated with the various scatterers are derived. Effectiveness of the 2-D state-space technique is tested on static range data collected on a complex conical target model; its accuracy to extract target length is judged and compared with the physical measurements. Validity of the proposed 2-D state-space technique and the Cramer-Rao bounds are demonstrated through data collected on the target model.
Summary
This work describes the computation of scatterers that lay on the body of a real target which are depicted in radar images. A novelty of the approach is the target echoes collected by the radar are formulated into the first Fornasini-Marchesini (F-M) state space model to compute poles that give...
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A new multiple choice comprehension test for MT
May 26, 2014
Conference Paper
Published in:
Automatic and Manual Metrics for Operation Translation Evaluation Workshop, 9th Int. Conf. on Language Resources and Evaluation (LREC 2014), 26 May 2014.
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Summary
We present results from a new machine translation comprehension test, similar to those developed in previous work (Jones et al., 2007). This test has documents in four conditions: (1) original English documents; (2) human translations of the documents into Arabic; conditions (3) and (4) are machine translations of the Arabic documents into English from two different MT systems. We created two forms of the test: Form A has the original English documents and output from the two Arabic-to-English MT systems. Form B has English, Arabic, and one of the MT system outputs. We administered the comprehension test to three subject types recruited in the greater Boston area: (1) native English speakers with no Arabic skills, (2) Arabic language learners, and (3) Native Arabic speakers who also have English language skills. There were 36 native English speakers, 13 Arabic learners, and 11 native Arabic speakers with English skills. Subjects needed an average of 3.8 hours to complete the test, which had 191 questions and 59 documents. Native English speakers with no Arabic skills saw Form A. Arabic learners and native Arabic speakers saw form B.
Summary
We present results from a new machine translation comprehension test, similar to those developed in previous work (Jones et al., 2007). This test has documents in four conditions: (1) original English documents; (2) human translations of the documents into Arabic; conditions (3) and (4) are machine translations of the Arabic...
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Standardized ILR-based and task-based speech-to-speech MT evaluation
May 26, 2014
Conference Paper
Published in:
Automatic and Manual Metrics for Operation Translation Evaluation Workshop, 9th Int. Conf. on Language Resources and Evaluation (LREC 2014), 26 May 2014.
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Summary
This paper describes a new method for task-based speech-to-speech machine translation evaluation, in which tasks are defined and assessed according to independent published standards, both for the military tasks performed and for the foreign language skill levels used. We analyze task success rates and automatic MT evaluation scores (BLEU and METEOR) for 220 role-play dialogs. Each role-play team consisted of one native English-speaking soldier role player, one native Pashto-speaking local national role player, and one Pashto/English interpreter. The overall PASS score, averaged over all of the MT dialogs, was 44%. The average PASS rate for HT was 95%, which is important because a PASS requires that the role-players know the tasks. Without a high PASS rate in the HT condition, we could not be sure that the MT condition was not being unfairly penalized. We learned that success rates depended as much on task simplicity as it did upon the translation condition: 67% of simple, base-case scenarios were successfully completed using MT, whereas only 35% of contrasting scenarios with even minor obstacles received passing scores. We observed that MT had the greatest chance of success when the task was simple and the language complexity needs were low.
Summary
This paper describes a new method for task-based speech-to-speech machine translation evaluation, in which tasks are defined and assessed according to independent published standards, both for the military tasks performed and for the foreign language skill levels used. We analyze task success rates and automatic MT evaluation scores (BLEU and...
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Wind information requirements for NextGen applications - phase 2 final report - framework refinement and application to four-dimensional trajectory based operations (4D-TBO) and interval management (IM)
May 20, 2014
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-418
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Summary
Accurate wind information is of fundamental importance to some of the critical future air traffic concepts under the FAA's Next Generation Air Transportation System (NextGen) initiative. Concepts involving time elements, such as Four-Dimensional Trajectory Based Operations (4D-TBO) and Interval Management (IM), are especially sensitive to wind information accuracy. There is a growing need to establish appropriate concepts of operation and target performance requirements accounting for wind information accuracy for these types of procedure, and meeting these needs is the purpose of this project. In the first phase of this work, a Wind Information Analysis Framework was developed to help explore the relationship of wind information to NextGen application performance. A refined version of the framework has been developed for the Phase 2 work that highlights the role stakeholders play in defining Air Traffic Control (ATC) scenarios, distinguishes wind scenarios into benign, moderate, severe, and extreme categories, and more clearly identifies what and how wind requirements recommendations are developed from the performance assessment trade-spaces. This report documents how this refined analysis framework has been used in Phase 2 of the work in terms of: -Refined wind information metrics and wind scenario selection process applicable to a broader range of NextGen applications, with particular focus on 4D-TBO and IM. -Expanded and refined studies of 4D-TBO applications with current Flight Management Systems (FMS) (with MITRE collaboration) to identify more accurate trade-spaces using operational FMS capabilities with higher-fidelity aircraft models. -Expansion of the 4D-TBO study using incremental enhancements possible in future FMSs (with Honeywell collaboration), specifically in the area of wind blending algorithms to quantify performance improvement potential from near-term avionics refinements. -Demonstrating the adaptability of the Wind Information Analysis Framework by using it to identify initial wind information needs for IM applications.
Summary
Accurate wind information is of fundamental importance to some of the critical future air traffic concepts under the FAA's Next Generation Air Transportation System (NextGen) initiative. Concepts involving time elements, such as Four-Dimensional Trajectory Based Operations (4D-TBO) and Interval Management (IM), are especially sensitive to wind information accuracy. There is...
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Unmanned aircraft sense and avoid radar: surrogate flight testing performance evaluation
May 19, 2014
Conference Paper
Published in:
RadarCon14: IEEE Radar Conf., 19-23 May 2014.
Summary
Unmanned aircraft systems (UAS) have proven to have distinct advantages compared to manned aircraft for a variety of tasks. Current airspace regulations require a capability to sense and avoid other aircraft to replace the ability of a pilot to see and avoid other traffic. A prototype phased-array radar was developed and tested to demonstrate a capability to support the sense and avoid (SAA) requirement and to validate radar performance models. Validated radar models enable evaluation of other radar systems in simulation. This paper provides an overview of the unique radar technology, and focuses on radar performance and model validation as demonstrated through a flight testing campaign. Performance results demonstrate that the prototype SAA radar system can provide sufficient accuracy to sense avoid non-cooperative aircraft.
Summary
Unmanned aircraft systems (UAS) have proven to have distinct advantages compared to manned aircraft for a variety of tasks. Current airspace regulations require a capability to sense and avoid other aircraft to replace the ability of a pilot to see and avoid other traffic. A prototype phased-array radar was developed...
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Development and use of a comprehensive humanitarian assessment tool in post-earthquake Haiti
May 13, 2014
Journal Article
Published in:
Procedia Eng., Vol. 78, 2014, pp. 10-21.
Summary
This paper describes a comprehensive humanitarian assessment tool designed and used following the January 2010 Haiti earthquake. The tool was developed under Joint Task Force -- Haiti coordination using indicators of humanitarian needs to support decision making by the United States Government, agencies of the United Nations, and various non-governmental organizations. A set of questions and data collection methodology were developed by a collaborative process involving a broad segment of the Haiti humanitarian relief community and used to conduct surveys in internally displaced person settlements and surrounding communities for a four-month period starting on 15 March 2010. Key considerations in the development of the assessment tool and data collection methodology, representative analysis results, and observations from the operational use of the tool for decision making are reported. The paper concludes with lessons learned and recommendations for design and use of similar tools in the future.
Summary
This paper describes a comprehensive humanitarian assessment tool designed and used following the January 2010 Haiti earthquake. The tool was developed under Joint Task Force -- Haiti coordination using indicators of humanitarian needs to support decision making by the United States Government, agencies of the United Nations, and various non-governmental...
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Robust keys from physical unclonable functions
May 6, 2014
Conference Paper
Published in:
Proc. 2014 IEEE Int. Symp. on Hardware-Oriented Security and Trust, HOST, 6-7 May 2014.
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Summary
Weak physical unclonable functions (PUFs) can instantiate read-proof hardware tokens (Tuyls et al. 2006, CHES) where benign variation, such as changing temperature, yields a consistent key, but invasive attempts to learn the key destroy it. Previous approaches evaluate security by measuring how much an invasive attack changes the derived key (Pappu et al. 2002, Science). If some attack insufficiently changes the derived key, an expert must redesign the hardware. An unexplored alternative uses software to enhance token response to known physical attacks. Our approach draws on machine learning. We propose a variant of linear discriminant analysis (LDA), called PUF LDA, which reduces noise levels in PUF instances while enhancing changes from known attacks. We compare PUF LDA with standard techniques using an optical coating PUF and the following feature types: raw pixels, fast Fourier transform, short-time Fourier transform, and wavelets. We measure the true positive rate for valid detection at a 0% false positive rate (no mistakes on samples taken after an attack). PUF LDA improves the true positive rate from 50% on average (with a large variance across PUFs) to near 100%. While a well-designed physical process is irreplaceable, PUF LDA enables system designers to improve the PUF reliability-security tradeoff by incorporating attacks without redesigning the hardware token.
Summary
Weak physical unclonable functions (PUFs) can instantiate read-proof hardware tokens (Tuyls et al. 2006, CHES) where benign variation, such as changing temperature, yields a consistent key, but invasive attempts to learn the key destroy it. Previous approaches evaluate security by measuring how much an invasive attack changes the derived key...
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Digital pixel CMOS focal plane array with on-chip multiply accumulate units for low-latency image processing
May 5, 2014
Conference Paper
Published in:
SPIE, Vol. 9070, Infrared Technology and Applications XL, 5 May 2014, 90703B.
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Summary
A digital pixel CMOS focal plane array has been developed to enable low latency implementations of image processing systems such as centroid trackers, Shack-Hartman wavefront sensors, and Fitts correlation trackers through the use of in-pixel digital signal processing (DSP) and generic parallel pipelined multiply accumulate (MAC) units. Light intensity digitization occurs at the pixel level, enabling in-pixel DSP and noiseless data transfer from the pixel array to the peripheral processing units. The pipelined processing of row and column image data prior to off chip readout reduces the required output bandwidth of the image sensor, thus reducing the latency of computations necessary to implement various image processing systems. Data volume reductions of over 80% lead to sub 10us latency for completing various tracking and sensor algorithms. This paper details the architecture of the pixel-processing imager (PPI) and presents some initial results from a prototype device fabricated in a standard 65nm CMOS process hybridized to a commercial off-the-shelf short-wave infrared (SWIR) detector array.
Summary
A digital pixel CMOS focal plane array has been developed to enable low latency implementations of image processing systems such as centroid trackers, Shack-Hartman wavefront sensors, and Fitts correlation trackers through the use of in-pixel digital signal processing (DSP) and generic parallel pipelined multiply accumulate (MAC) units. Light intensity digitization...
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Spectral subgraph detection with corrupt observations
May 4, 2014
Conference Paper
Published in:
Proc. IEEE Int. Conf. on Acoustics, Speech and Signal Processing, ICASSP, 4-9 May 2014.
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R&D area:
Summary
Recent work on signal detection in graph-based data focuses on classical detection when the signal and noise are both in the form of discrete entities and their relationships. In practice, the relationships of interest may not be directly observable, or may be observed through a noisy mechanism. The effects of imperfect observations add another layer of difficulty to the detection problem, beyond the effects of typical random fluctuations in the background graph. This paper analyzes the impact on detection performance of several error and corruption mechanisms for graph data. In relatively simple scenarios, the change in signal and noise power is analyzed, and this is demonstrated empirically in more complicated models. It is shown that, with enough side information, it is possible to fully recover performance equivalent to working with uncorrupted data using a Bayesian approach, and a simpler cost-optimization approach is shown to provide a substantial benefit as well.
Summary
Recent work on signal detection in graph-based data focuses on classical detection when the signal and noise are both in the form of discrete entities and their relationships. In practice, the relationships of interest may not be directly observable, or may be observed through a noisy mechanism. The effects of...
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Wind Information Requirements for NextGen Applications - Phase 2 Final Report(7.63 MB)
May 1, 2014
Project Report
Published in:
Project Report ATC-418, MIT Lincoln Laboratory
Summary
Accurate wind information is of fundamental importance to some of the critical future air traffic concepts envisioned under the FAA’s Next Generation Air Transportation System (NextGen) initiative. In the first phase of this work, a Wind Information Analysis Framework was developed to help explore the relationship of wind information to NextGen application performance. A refined version of the framework has been developed for the Phase 2 work.
Summary
Accurate wind information is of fundamental importance to some of the critical future air traffic concepts envisioned under the FAA’s Next Generation Air Transportation System (NextGen) initiative. In the first phase of this work, a Wind Information Analysis Framework was developed to help explore the relationship of wind information to...
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