Publications
Hyperspectral environmental suite for the Geostationary Operational Environmental Satellite (GOES)
April 12, 2004
Conference Paper
Published in:
SPIE Vol. 5425, Algorithms and Technologies for Multispectral, Hyperspectral, and Ultraspectral Imagery X, 12-15 April 2004, pp. 329-340.
Summary
The GOES satellites will fly a Hyperspectral Environmental Suite (HES) on GOES-R in the 2012 timeframe. The approximately 1500 spectral channels (technically ultraspectral), leading to improved vertical resolution, and approximately five times faster coverage rate planned for the sounder in this suite will greatly exceed the capabilities of the current GOES series instrument with its 18 spectral channels. In the GOES-R timeframe, frequent measurements afforded by geostationary orbits will be critical for numerical weather prediction models. Since the current GOES soundings are assimilated into numerical weather prediction models to improve the validity of model outputs, particularly in areas with little radiosonde coverage, this hyperspectral capability in the thermal infrared will significantly improve sounding performance for weather prediction in the western hemisphere, while providing and enhancing other products. Finer spatial resolution is planned for mesoscale observation of water vapor variations. The improvements over the previous GOES sounders and a primary difference from other planned instruments stem from two-dimensional focal plane array availability. These carry an additional set of challenges in terms of instrument specifications, which will be discussed. As a suite, HES is planned with new capabilities for coastal ocean coverage with the goal of including open ocean coverage. These new planned imaging applications, which will be either multispectral or hyperspectral, will also be discussed.
Summary
The GOES satellites will fly a Hyperspectral Environmental Suite (HES) on GOES-R in the 2012 timeframe. The approximately 1500 spectral channels (technically ultraspectral), leading to improved vertical resolution, and approximately five times faster coverage rate planned for the sounder in this suite will greatly exceed the capabilities of the current...
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InGaAsP/InP quantum-well electrorefractive modulators with sub-volt V[pi]
April 12, 2004
Conference Paper
Published in:
SPIE Vol. 5435, Enabling Photonic Technologies for Aerospace Applications VI, 12-16 April 2004, pp. 53-63.
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Summary
Advanced analog-optical sensor, signal processing and communication systems could benefit significantly from wideband (DC to > 50 GHz) optical modulators having both low half-wave voltage (V[pi]) and low optical insertion loss. An important figure-of-merit for modulators used in analog applications is TMAX/V[pi], where TMAX is the optical transmission of the modulator when biased for maximum transmission. Candidate electro-optic materials for realizing these modulators include lithium niobate (LiNbO3), polymers, and semiconductors, each of which has its own set of advantages and disadvantages. In this paper, we report the development of 1.5-um-wavelength Mach-Zehnder modulators utilizing the electrorefractive effect in InGaAsP/InP symmetric, uncoupled semiconductor quantum-wells. Modulators with 1-cm-long, lumped-element electrodes are found to have a push-pull V[pi] of 0.9V (V[pi]L = 9 V-mm) and 18-dB fiber-to-fiber insertion loss (TMAX/V[pi] = 0.018). Fabry-Perot cutback measurements reveal a waveguide propagation loss of 7 dB/cm and a waveguide-to-fiber coupling loss of 5 dB/facet. The relatively high propagation loss results from a combination of below-bandedge absorption and scattering due to waveguide-sidewall roughness. Analyses show that most of the coupling loss can be eliminated though the use of monolithically integrated invertedtaper optical-mode converters, thereby allowing these modulators to exceed the performance of commercial LiNbO3 modulators (TMAX/V[pi] ~ 0.1). We also report the analog modulation characteristics of these modulators.
Summary
Advanced analog-optical sensor, signal processing and communication systems could benefit significantly from wideband (DC to > 50 GHz) optical modulators having both low half-wave voltage (V[pi]) and low optical insertion loss. An important figure-of-merit for modulators used in analog applications is TMAX/V[pi], where TMAX is the optical transmission of the...
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Corridor Integrated Weather System operation benefits 2002-2003 : initial estimates of convective weather delay reduction
April 9, 2004
Project Report
Published in:
MIT Lincoln Laboratory Report ATC-313
Summary
The Corridor Integrated Weather System (CIWS) seeks to improve safety and reduce delay by providing accurate, automated, rapidly updated information on storm locations and echo tops along with two-hour high-resolution animated growth and decay convective storm forecasts. An operational benefits assessment was conducted using on-site observations of CIWS usage at major en route control centers in the Northeast and Great Lakes corridors and the Air Traffic Control Systems Command Center (ATCSCC) during six multi-day periods in 2003. This first phase of the benefit assessment characterizes major safety and delay reduction benefits and quantifies the delay reduction benefits for two key Traffic Flow Management (TFM) user benefits: "keeping air routes open longer/reopening closed routes soon" and "proactive, efficient reroutes of traffic around storm cells." The overall CIWS delay reduction for these two benefits is 40,000 to 69,000 hours annually with an equivalent monetary value ot $127M to $26M annually. Convective weather delays at most of the major airports in the test domain, normalized by thunderstorm frequency, decreased after new CIWS echo tops and forecast products were introduced. Recommendations are made for near-term, low-cost improvements to the CIWS demonstration system to further increase the operational benefits.
Summary
The Corridor Integrated Weather System (CIWS) seeks to improve safety and reduce delay by providing accurate, automated, rapidly updated information on storm locations and echo tops along with two-hour high-resolution animated growth and decay convective storm forecasts. An operational benefits assessment was conducted using on-site observations of CIWS usage at...
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A tutorial on text-independent speaker verification
April 1, 2004
Journal Article
Published in:
EURASIP J. on Appl. Sig. Proc., Vol. 4, 1 April 2004, pp. 430-451.
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Summary
This paper presents an overview of a state-of-the-art text-independent speaker verification system. First, an introduction proposes a modular scheme of the training and test phases of a speaker verification system. Then, the most commonly speech parameterization used in speaker verification, namely, cepstral analysis, is detailed. Gaussian mixture modeling, which is the speaker modeling technique used in most systems, is then explained. A few speaker modeling alternatives, namely, neural networks and support vector machines, are mentioned. Normalization of scores is then explained, as this is a very important step to deal with real-world data. The evaluation of a speaker verification system is then detailed, and the detection error trade-off (DET) curve is explained. Several extensions of speaker verification are then enumerated, including speaker tracking and segmentation by speakers. Then, some applications of speaker verification are proposed, including on-site applications, remote applications, applications relative to structuring audio information, and games. Issues concerning the forensic area are then recalled, as we believe it is very important to inform people about the actual performance and limitations of speaker verification systems. This paper concludes by giving a few research trends in speaker verification for the next couple of years.
Summary
This paper presents an overview of a state-of-the-art text-independent speaker verification system. First, an introduction proposes a modular scheme of the training and test phases of a speaker verification system. Then, the most commonly speech parameterization used in speaker verification, namely, cepstral analysis, is detailed. Gaussian mixture modeling, which is...
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Photoresist outgassing: a potential Achilles heel for short wavelength optical lithography?
February 22, 2004
Conference Paper
Published in:
SPIE Vol. 5376, Advances in Resist Technology and Processing XXI, 22-27 February 2004, pp. 1-15.
Summary
The outgassing of volatile organic compounds during photoresist exposure at short wavelengths (
Summary
The outgassing of volatile organic compounds during photoresist exposure at short wavelengths (
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Analysis of multitarget detection for speaker and language recognition
January 1, 2004
Conference Paper
Published in:
ODYSSEY 2004, 31 May-4 June 2004.
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Summary
The general multitarget detection (or open-set identification) task is the intersection of the more common tasks of close-set identification and open-set verification/detection. In this task, a bank of parallel detectors process an input and must decide if the input is from one of the target classes and, if so, which one (or a small set containing the true one). In this paper, we analyze theoretically and empirically the behavior of a multitarget detector and relate the identification confusion error and the miss and false alarm detection errors in predicting performance. We show analytically that the performance of a multitarget detector can be predicted from single detector performance using speaker and language recognition data and experiments.
Summary
The general multitarget detection (or open-set identification) task is the intersection of the more common tasks of close-set identification and open-set verification/detection. In this task, a bank of parallel detectors process an input and must decide if the input is from one of the target classes and, if so, which...
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Automated lip-reading for improved speech intelligibility
January 1, 2004
Conference Paper
Published in:
Proc. of the IEEE Int. Conf. on Acoustics, Speech, and Signal Processing, ICASSP, Vol. I, 17-21 May 2004, pp. I-701 - I-704.
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Summary
Various psycho-acoustical experiments have concluded that visual features strongly affect the perception of speech. This contribution is most pronounced in noisy environments where the intelligibility of audio-only speech is quickly degraded. An exploration of the effectiveness for extracted visual features such as lip height and width for improving speech intelligibility in noisy environments is provided in this paper. The intelligibility content of these extracted visual features will be investigated through an intelligibility test on an animated rendition of the video generated from the extracted visual features, as well as on the original video. These experiments demonstrate that the extracted video features do contain important aspects of intelligibility that may be utilized in augmenting speech enhancement and coding applications. Alternatively, these extracted visual features can be transmitted in a bandwidth effective way to augment speech coders.
Summary
Various psycho-acoustical experiments have concluded that visual features strongly affect the perception of speech. This contribution is most pronounced in noisy environments where the intelligibility of audio-only speech is quickly degraded. An exploration of the effectiveness for extracted visual features such as lip height and width for improving speech intelligibility...
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High performance computing productivity model synthesis
January 1, 2004
Journal Article
Published in:
Int. J. High Perform. Comp. App., Vol. 12, No. 4, Winter 2004, pp. 505-516.
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Summary
The Defense Advanced Research Projects Agency (DARPA) High Productivity Computing System (HPCS) program is developing systems that deliver increased value to users at a rate commensurate with the rate of improvement in the underlying technologies. For example, if the relevant technology was silicon, the goal of such a system would be to double in productivity (or value) every 18 months, following Moore's law. The key questions are how we define and measure productivity, and what the underlying technologies that affect productivity are. The goal of this paper is to synthesize from several different productivity models a single model that captures the main features of all the models. In addition we will start the process of putting the model on an empirical foundation by incorporating selected results from the software engineering and high performance computing (HPC) communities. An asymptotic analysis of the model is conducted to check that it makes sense in certain special cases. The model is extrapolated to a HPC context and several examples are explored, including HPC centers, HPC users, and interactive grid computing. Finally, the model hints at a profoundly different way of viewing HPC systems, where the user must be included in the equation, and innovative hardware is a key aspect to lowering the very high costs of HPC software.
Summary
The Defense Advanced Research Projects Agency (DARPA) High Productivity Computing System (HPCS) program is developing systems that deliver increased value to users at a rate commensurate with the rate of improvement in the underlying technologies. For example, if the relevant technology was silicon, the goal of such a system would...
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HPC productivity: an overarching view
January 1, 2004
Journal Article
Published in:
Int. J. High Perform. Comp. App., Vol. 18, No. 4, Winter 2004, pp. 393-397.
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Summary
The Defense Advanced Research Projects Agency (DARPA) High Productivity Computing Systems (HPCS) program is focused on providing a new generation of economically viable high productivity computing systems for national security and for the industrial user community. The value of a high performance computing (HPC) system to a user includes many factors, such as execution time on a particular problem, software development time, direct hardware costs, and indirect administrative and maintenance costs. This special issue, which focuses on HPC productivity, brings together, for the first time, a series of novel papers written by several distinguished authors who share their views on this topic. The topic of productivity in HPC is very new and the authors have been encouraged to speculate. The goal of this first paper is to present an overarching context and framework for the other papers and to define some common ideas that have emerged in considering the problem of HPC productivity. In addition, this paper defines several characteristic HPC workflows that are useful for understanding how users exploit HPC systems, and discusses the role of activity and purpose benchmarks in establishing an empirical basis for HPC productivity.
Summary
The Defense Advanced Research Projects Agency (DARPA) High Productivity Computing Systems (HPCS) program is focused on providing a new generation of economically viable high productivity computing systems for national security and for the industrial user community. The value of a high performance computing (HPC) system to a user includes many...
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MatlabMPI
January 1, 2004
Journal Article
Published in:
Journal of Parallel and Distributed Computing, Vol. 64, No. 8, pp. 997-1005.
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Summary
In many projects the true costs of high performance computing are currently dominated by software. Addressing these costs may require shifting to higher level languages such as Matlab. MatlabMPI is a Matlab implementation of the Message Passing Interface (MPI) standard and allows any Matlab program to exploit multiple processors. MatlabMPI currently implements the basic six functions that are the core of the MPI point-to-point communications standard. The key technical innovation of MatlabMPI is that it implements the widely used MPI “look and feel” on top of standard Matlab file I/O, resulting in an extremely compact (?350 lines of code) and “pure” implementation which runs anywhere Matlab runs, and on any heterogeneous combination of computers. The performance has been tested on both shared and distributed memory parallel computers (e.g. Sun, SGI, HP, IBM, Linux, MacOSX and Windows). MatlabMPI can match the bandwidth of C based MPI at large message sizes. A test image filtering application using MatlabMPI achieved a speedup of ?300 using 304 CPUs and ?15% of the theoretical peak (450 Gigaflops) on an IBM SP2 at the Maui High Performance Computing Center. In addition, this entire parallel benchmark application was implemented in 70 software-lines-of-code, illustrating the high productivity of this approach. MatlabMPI is available for download on the web.
Summary
In many projects the true costs of high performance computing are currently dominated by software. Addressing these costs may require shifting to higher level languages such as Matlab. MatlabMPI is a Matlab implementation of the Message Passing Interface (MPI) standard and allows any Matlab program to exploit multiple processors. MatlabMPI...
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