The Experts below are selected from a list of 83004 Experts worldwide ranked by ideXlab platform
Tim Yardley - One of the best experts on this subject based on the ideXlab platform.
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the virtual power system Testbed and inter Testbed integration
USENIX Security Symposium, 2009Co-Authors: David C Bergman, David M. Nicol, Dong Jin, Tim YardleyAbstract:The Virtual Power System Testbed (VPST) at University of Illinois at Urbana-Champaign is part of the Trustworthy Cyber Infrastructure for the Power Grid (TCIP) and is maintained by members of the Information Trust Institute (ITI). VPST is designed to be integrated with other Testbeds across the country to explore performance and security of Supervisory Control And Data Acquisition (SCADA) protocols and equipment. We discuss potential use cases in order to motivate the integration of VPST with other Testbeds, identify requirements of interconnected Testbeds, and describe our design for integration with VPST.
A F Boden - One of the best experts on this subject based on the ideXlab platform.
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The Palomar Testbed Interferometer
The Astrophysical Journal, 2009Co-Authors: M. Mark Colavita, Michael Shao, J. K. Wallace, B. E. Hines, Yekta Gursel, Fabien Malbet, Dean L. Palmer, X. P. Pan, A F BodenAbstract:The Palomar Testbed Interferometer (PTI) is a long-baseline infrared interferometer located at Palomar Observatory, California. It was built as a Testbed for interferometric techniques applicable to the Keck Interferometer. First fringes were obtained in 1995 July. PTI implements a dual-star architecture, tracking two stars simultaneously for phase referencing and narrow-angle astrometry. The three fixed 40 cm apertures can be combined pairwise to provide baselines to 110 m. The interferometer actively tracks the white-light fringe using an array detector at 2.2 μm and active delay lines with a range of ±38 m. Laser metrology of the delay lines allows for servo control, and laser metrology of the complete optical path enables narrow-angle astrometric measurements. The instrument is highly automated, using a multiprocessing computer system for instrument control and sequencing.
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the palomar Testbed interferometer calibrator catalog
Astrophysical Journal Supplement Series, 2008Co-Authors: G T Van Belle, Michelle Creecheakman, J Coyne, A F Boden, R L Akeson, David R Ciardi, K M Rykoski, R R Thompson, Benjamin F LaneAbstract:The Palomar Testbed Interferometer (PTI) archive of observations between 1998 and 2005 is examined for objects appropriate for calibration of optical long-baseline interferometer observations—stars that are predictably pointlike and single. Approximately 1400 nights of data on 1800 objects were examined for this investigation. We compare those observations to an intensively studied object that is a suitable calibrator, HD 217014, and statistically compare each candidate calibrator to that object by computing both a Mahalanobis distance and a principal component analysis. Our hypothesis is that the frequency distribution of visibility data associated with calibrator stars differs from noncalibrator stars such as binary stars. Spectroscopic binaries resolved by PTI, objects known to be unsuitable for calibrator use, are similarly tested to establish detection limits of this approach. From this investigation, we find more than 350 observed stars suitable for use as calibrators (with an additional ≈140 being rejected), corresponding to ≳95% sky coverage for PTI. This approach is noteworthy in that it rigorously establishes calibration sources through a traceable, empirical methodology, leveraging the predictions of spectral energy distribution modeling but also verifying it with the rich body of PTI's on-sky observations.
David C Bergman - One of the best experts on this subject based on the ideXlab platform.
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the virtual power system Testbed and inter Testbed integration
USENIX Security Symposium, 2009Co-Authors: David C Bergman, David M. Nicol, Dong Jin, Tim YardleyAbstract:The Virtual Power System Testbed (VPST) at University of Illinois at Urbana-Champaign is part of the Trustworthy Cyber Infrastructure for the Power Grid (TCIP) and is maintained by members of the Information Trust Institute (ITI). VPST is designed to be integrated with other Testbeds across the country to explore performance and security of Supervisory Control And Data Acquisition (SCADA) protocols and equipment. We discuss potential use cases in order to motivate the integration of VPST with other Testbeds, identify requirements of interconnected Testbeds, and describe our design for integration with VPST.
David M. Nicol - One of the best experts on this subject based on the ideXlab platform.
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the virtual power system Testbed and inter Testbed integration
USENIX Security Symposium, 2009Co-Authors: David C Bergman, David M. Nicol, Dong Jin, Tim YardleyAbstract:The Virtual Power System Testbed (VPST) at University of Illinois at Urbana-Champaign is part of the Trustworthy Cyber Infrastructure for the Power Grid (TCIP) and is maintained by members of the Information Trust Institute (ITI). VPST is designed to be integrated with other Testbeds across the country to explore performance and security of Supervisory Control And Data Acquisition (SCADA) protocols and equipment. We discuss potential use cases in order to motivate the integration of VPST with other Testbeds, identify requirements of interconnected Testbeds, and describe our design for integration with VPST.
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scada cyber security Testbed development
North American Power Symposium, 2006Co-Authors: C. M. Davis, Chris Grier, Thomas J. Overbye, Joseph Euzebe Tate, David M. Nicol, Hamed Okhravi, D NicolAbstract:New technologies are increasing the vulnerability of the power system to cyber security threats. Dealing with these threats and determining vulnerabilities is an important task for utilities. This paper presents the development of a Testbed designed to assess the vulnerabilities introduced by using public networks for communication.
Xiaolei Zhang - One of the best experts on this subject based on the ideXlab platform.
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wide field imaging interferometry Testbed i purpose Testbed design data and synthesis algorithms
Astronomical Telescopes and Instrumentation, 2003Co-Authors: David Leisawitz, Brad J Frey, Douglas B Leviton, Anthony J Martino, William L Maynard, Lee G Mundy, Stephen A Rinehart, Stacy H Teng, Xiaolei ZhangAbstract:The Wide-field Imaging Interferometry Testbed was designed to validate, experiment with, and refine the technique of wide field mosaic imaging for optical/IR interferometers. We offer motivation for WIIT, present the Testbed design, and describe algorithms that can be used to reduce the data from a spatial and spectral Michelson interferometer. A conventional single-detector Michelson interferometer operating with narrow bandwidth at center wavelength lc is limited in its field of view to the primary beam of the individual telescope apertures, or ~λc/dtel radians, where dtel is the telescope diameter. Such a field is too small for many applications; often one wishes to image extended sources. We are developing and testing techniques analogous to the mosaicing method employed in millimeter and radio astronomy, but applicable to optical/IR Michelson interferometers, in which beam combination is done in the pupil plane. An Npix × Npix array detector placed in the image plane of the interferometer is used to record simultaneously the fringe patterns from many contiguous telescope fields, effectively multiplying the field size by Npix/2, where the factor 2 allows for Nyquist sampling. This technique will be especially valuable for interferometric space observatories, such as the Space Infrared Interferometric Telescope and the Submillimeter Probe of the Evolution of Cosmic Structure. © (2003) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
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The Wide Field Imaging Interferometry Testbed
2001 IEEE Aerospace Conference Proceedings (Cat. No.01TH8542), 1Co-Authors: Xiaolei Zhang, David Leisawitz, Douglas B Leviton, Anthony J Martino, Lee Feinberg, John C. MatherAbstract:We are developing a Wide-Field Imaging Interferometry Testbed (WIIT) in support of design studies for NASA's future space interferometry missions, in particular the SPIRIT and SPECS far-infrared/submillimeter interferometers. WIIT operates at optical wavelengths and uses Michelson beam combination to achieve both wide-field imaging and high-resolution spectroscopy. It will be used chiefly to test the feasibility of using a large-format detector array at the image plane of the sky to obtain wide-field interferometry images through mosaicing techniques. In this setup each detector pixel records interferograms corresponding to averaging a particular pointing range on the sky as the optical path length is scanned and as the baseline separation and orientation is varied. The final image is constructed through spatial and spectral Fourier transforms of the recorded interferograms for each pixel, followed by a mosaic/joint-deconvolution procedure of all the pixels. In this manner the image within the pointing range of each detector pixel is further resolved to an angular resolution corresponding to the maximum baseline separation for fringe measurements. We present the motivation for building the Testbed, show the optical, mechanical, control, and data system design, and describe the image processing requirements and algorithms. WIIT is presently under construction at NASA's Goddard Space Flight Center.
