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  • Aircraft Propulsion and Power  (4)
  • Conservation of Natural Resources  (4)
  • Astrophysics
  • 2000-2004  (10)
  • 1
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    A global paleoclimate observing system (2001)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2001-07-11
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Alverson, K -- Bradley, R -- Briffa, K -- Cole, J -- Hughes, M -- Larocque, I -- Pedersen, T -- Thompson, L -- Tudhope, S -- New York, N.Y. -- Science. 2001 Jul 6;293(5527):47-8.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/11444288" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Carbon Dioxide/metabolism ; *Climate ; Cnidaria/physiology ; Conservation of Natural Resources ; Greenhouse Effect ; Humans ; Ice ; Oceans and Seas ; Rain ; Seawater/analysis/chemistry ; Specimen Handling/*methods ; Temperature ; Time Factors ; Trees/growth & development/physiology
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 2
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    Historical overfishing and the recent collapse of coastal ecosystems (2001)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2001-07-28
    Description: Ecological extinction caused by overfishing precedes all other pervasive human disturbance to coastal ecosystems, including pollution, degradation of water quality, and anthropogenic climate change. Historical abundances of large consumer species were fantastically large in comparison with recent observations. Paleoecological, archaeological, and historical data show that time lags of decades to centuries occurred between the onset of overfishing and consequent changes in ecological communities, because unfished species of similar trophic level assumed the ecological roles of overfished species until they too were overfished or died of epidemic diseases related to overcrowding. Retrospective data not only help to clarify underlying causes and rates of ecological change, but they also demonstrate achievable goals for restoration and management of coastal ecosystems that could not even be contemplated based on the limited perspective of recent observations alone.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Jackson, J B -- Kirby, M X -- Berger, W H -- Bjorndal, K A -- Botsford, L W -- Bourque, B J -- Bradbury, R H -- Cooke, R -- Erlandson, J -- Estes, J A -- Hughes, T P -- Kidwell, S -- Lange, C B -- Lenihan, H S -- Pandolfi, J M -- Peterson, C H -- Steneck, R S -- Tegner, M J -- Warner, R R -- New York, N.Y. -- Science. 2001 Jul 27;293(5530):629-37.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA 92093-0244, USA. jbcj@ucsd.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/11474098" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Archaeology ; Bacteria ; Cnidaria ; Conservation of Natural Resources ; *Ecosystem ; Eutrophication ; *Fishes ; Geologic Sediments ; Humans ; *Marine Biology ; Seaweed ; Shellfish ; Time Factors
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 3
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    Regional-scale assembly rules and biodiversity of coral reefs (2001)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2001-05-26
    Description: Tropical reef fishes and corals exhibit highly predictable patterns of taxonomic composition across the Indian and Pacific Oceans. Despite steep longitudinal and latitudinal gradients in total species richness, the composition of these key taxa is constrained within a remarkably narrow range of values. Regional-scale variation in reef biodiversity is best explained by large-scale patterns in the availability of shallow-water habitat. Once habitat area is accounted for, there is surprisingly little residual effect of latitude or longitude. Low-diversity regions are most vulnerable to human impacts such as global warming, underscoring the urgent need for integrated management at multinational scales.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Bellwood, D R -- Hughes, T P -- New York, N.Y. -- Science. 2001 May 25;292(5521):1532-5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Centre for Coral Reef Biodiversity, Department of Marine Biology, James Cook University, Townsville, Qld 4811, Australia. david.bellwood@jcu.edu.au〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/11375488" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; *Cnidaria/classification/physiology ; Conservation of Natural Resources ; *Ecosystem ; *Fishes/classification/physiology ; Geography ; Greenhouse Effect ; Indian Ocean ; Pacific Ocean ; Temperature
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 4
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    Global trajectories of the long-term decline of coral reef ecosystems (2003)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2003-08-16
    Description: Degradation of coral reef ecosystems began centuries ago, but there is no global summary of the magnitude of change. We compiled records, extending back thousands of years, of the status and trends of seven major guilds of carnivores, herbivores, and architectural species from 14 regions. Large animals declined before small animals and architectural species, and Atlantic reefs declined before reefs in the Red Sea and Australia, but the trajectories of decline were markedly similar worldwide. All reefs were substantially degraded long before outbreaks of coral disease and bleaching. Regardless of these new threats, reefs will not survive without immediate protection from human exploitation over large spatial scales.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Pandolfi, John M -- Bradbury, Roger H -- Sala, Enric -- Hughes, Terence P -- Bjorndal, Karen A -- Cooke, Richard G -- McArdle, Deborah -- McClenachan, Loren -- Newman, Marah J H -- Paredes, Gustavo -- Warner, Robert R -- Jackson, Jeremy B C -- New York, N.Y. -- Science. 2003 Aug 15;301(5635):955-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Paleobiology, MRC-121, National Museum of Natural History, Post Office Box 37012, Smithsonian Institution, Washington, DC 20013-7012, USA. pandolfi.john@nmnh.si.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/12920296" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Anthozoa/*growth & development ; Conservation of Natural Resources ; Culture ; *Ecosystem ; Humans ; Population Dynamics ; Principal Component Analysis ; Time Factors
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 5
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    Vibration Test Demonstrated Dynamic Capability of an Operating Stirling Convertor (2001)
    In:  CASI
    Details
    Publication Date: 2018-06-05
    Description: The NASA Glenn Research Center and the U.S. Department of Energy are currently developing a high-efficiency, long-life, free piston Stirling convertor for use as an advanced spacecraft power system for future NASA missions. As part of this development, a Stirling Technology Demonstrator Converter (TDC), developed by Stirling Technology Company for the Department of Energy, was vibration tested at Glenn's Structural Dynamics Laboratory in November and December 1999. This testing demonstrated that the Stirling TDC is able to withstand the harsh random vibration (20 to 2000 Hz) seen during a typical spacecraft launch and to survive with no structural damage or functional power performance degradation, thereby enabling its use in future spacecraft power systems. Glenn and Stirling personnel conducted tests on a single 55 We TDC. The purpose was to characterize the TDC's structural response to vibration and to determine if the TDC could survive the vibration criteria established by the Jet Propulsion Laboratory for launch environments. The TDC was operated at full-stroke and full power conditions during the vibration testing.
    Keywords: Aircraft Propulsion and Power
    Type: Research and Technology 2000; NASA/TM-2001-210605
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  • 6
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    Far-Field Acoustic Characteristics of Multiple Blade-Vane Configurations for a High Tip Speed Fan (2004)
    In:  CASI
    Details
    Publication Date: 2019-07-10
    Description: The acoustic characteristics of a model high-speed fan stage were measured in the NASA Glenn 9- by 15-Foot Low Speed Wind Tunnel at takeoff and approach flight conditions. The fan was designed for a corrected rotor tip speed of 442 m/s (1450 ft/s), and had a powered core, or booster stage, giving the model a nominal bypass ratio of 5. A simulated engine pylon and nozzle bifurcation was contained within the bypass duct. The fan stage consisted of all combinations of 3 possible rotors, and 3 stator vane sets. The 3 rotors were (1) wide chord, (2) forward swept, and (3) shrouded. The 3 stator sets were (1) baseline, moderately swept, (2) swept and leaned, and (3) swept integral vane/frame which incorporated some of the swept and leaned features as well as eliminated the downstream support structure. The baseline configuration is considered to be the wide chord rotor with the radial vane stator. A flyover Effective Perceived Noise Level (EPNL) code was used to generate relative EPNL values for the various configurations. The swept and leaned stator showed a 3 EPNdB reduction at lower fan speeds relative to the baseline stator; while the swept integral vane/frame stator showed lowest noise levels at high fan speeds. The baseline, wide chord rotor was typically the quietest of the three rotors. A tone removal study was performed to assess the acoustic benefits of removing the fundamental rotor interaction tone and its harmonics. Reprocessing the acoustic results with the bypass tone removed had the most impact on reducing fan noise at transonic rotor speeds. Removal of the bypass rotor interaction tones (BPF and nBPF) showed up to a 6 EPNdB noise reduction at transonic rotor speeds relative to noise levels for the baseline (wide chord rotor and radial stator; all tones present) configuration.
    Keywords: Aircraft Propulsion and Power
    Type: NASA/TM-2004-213093 , E-14568 , NAS/1.15:2004-213093
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  • 7
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    Performance Optimization of a Rotor Alone Nacelle for Acoustic Fan Testing (2000)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: This paper describes the techniques, equipment, and results from the optimization of a two-axis traverse actuation system used to maintain concentricity between a sting-mounted fan and a wall-mounted nacelle in the 9 x 15 (9 Foot by 15 Foot Test Section) Low Speed Wind Tunnel (LSWT) at the NASA Glenn Research Center (GRC). The Rotor Alone Nacelle (RAN) system, developed at GRC by the Engineering Design and Analysis Division (EDAD) and the Acoustics Branch, used nacelle-mounted lasers and an automated control system to maintain concentricity as thermal and thrust operating loads displace the fan relative to the nacelle. This effort was critical to ensuring rig/facility safety and experimental consistency of the acoustic data from a statorless, externally supported nacelle configuration. Although the tip clearances were originally predicted to be about 0.020 in. at maximum rotor (fan) operating speed, proximity probe measurements showed that the nominal clearance was less than 0.004 in. As a result, the system was optimized through control-loop modifications, active laser cooling, data filtering and averaging, and the development of strict operational procedures. The resultant concentricity error of RAN was reduced to +/- 0.0031 in. in the Y-direction (horizontal) and +0.0035 in./-0.001 3 in. in the Z-direction (vertical), as determined by error analysis and experimental results. Based on the success of this project, the RAN system will be transitioned to other wind tunnel research programs at NASA GRC.
    Keywords: Aircraft Propulsion and Power
    Type: NASA/TM-2000-210599 , NAS 1.15:210599 , E-12557 , AIAA Paper 2001-0164 , Aerospace Sciences; Jan 08, 2001 - Jan 11, 2001; Reno, NV; United States
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  • 8
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    Sunyaev-Zeldovich Effect-Derived Distances to the High-Redshift Clusters (2000)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: We determine the distances to the z approximately equals 0.55 galaxy clusters MS 0451.6 - 0305 and Cl 0016 + 16 from a maximum-likelihood joint fit to interferometric Sunyaev-Zeldovich effect (SZE) and X-ray observations. We model the intracluster medium (ICM) using a spherical isothermal beta model. We quantify the statistical and systematic uncertainties inherent to these direct distance measurements, and we determine constraints on the Hubble parameter for three different cosmologies. For an Omega(sub M) = 0.3, Omega(sub lambda) = 0.7 cosmology, these distances imply a Hubble constant of 63(sup +12) (sub -9) (sup + 21) (sub -21) km/s Mp/c, where the uncertainties correspond to statistical followed by systematic at 68% confidence. The best-fit H(sub 0) is 57 km/s Mp/c for an open (Omega(sub M) = 0.3) universe and 52 km/s Mp/c for a flat (Omega(sub M) = 1) universe.
    Keywords: Astrophysics
    Type: Astrophysical Journal; 533; 38-49
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  • 9
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    The Distance and Mass of the Galaxy Cluster Abell 1995 Derived from Sunyaev-Zeldovich Effect and X-Ray Measurements (2000)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: We present multiwavelength observations of the Abell 1995 galaxy cluster. From an analysis of X-ray spectroscopy and imaging data, we derive the electron temperature, cluster core radius, and central electron number density. Using optical spectroscopy of 15 cluster members, we derive an accurate cluster redshift and velocity dispersion. Finally, the interferometric imaging of the Sunyaev-Zeldovich effect toward Abell 1995 at 28.5 GHz provides a measure of the integrated pressure through the cluster. The X-ray and Sunyaev-Zeldovich effect observations are combined to determine the angular diameter distance to the cluster of D(sub A) = 1294(sup +294 +438, sub -283 -458) Mpc (Statistical followed by systematic uncertainty), implying a Hubble constant of H(sub 0) = 52.2(sup +11.4 +18.5, sub -11.9 -17.7) km/s.Mpc for Omega(sub M) = 0.3 and Omega(sub lambda) = 0.7. We find a best-fit H(sub 0) of 46 km/s.Mpc for the Omega(sub M) = 1 and Omega(sub lambda) = 0 cosmology, and 48 km/s.Mpc for Omega(sub M) = 0.3 and Omega(sub lambda) = 0.0. The X-ray data are also used to derive a total cluster mass of M(sup HSE, sub tot)(r(sub 500)) = 5.18(sup +0.62, sub -0.48) x 10(exp 14)/h solar mass; the optical velocity dispersion yields an independent and consistent estimate of M(sup virial, sub tot)(r(sub 500)) = 6.35(sup +1.51, sub -1.19) X 10(exp 14) /h solar mass. Both of the total mass estimates are evaluated at a fiducial radius, r(sub 500) = 830 /h kpc, where the overdensity is 500 times the critical density. The total cluster mass is then combined with gas mass measurements to determine a cluster gas mass fraction of F(sub g) = 0.056(sup +0.010, sub -0.013) /h(sup 3/2) in combination with recent baryon density constraints, the measured gas mass fraction yields an upper limit on the mass density parameter of Omega(sub M) h(sup 1/2) 〈= 0.34(sup +/0.06, sub 0.05.
    Keywords: Astrophysics
    Type: Astrophysical Journal; 541; 37-48
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  • 10
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    Design and Integration of a Rotor Alone Nacelle for Acoustic Fan Testing (2001)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: A brief summary of the design, integration and testing of a rotor alone nacelle (RAN) in NASA Glenn's 9'x 15' Low Speed Wind Tunnel (LSWT) is presented. The purpose of the RAN system was to provide an "acoustically clean" flow path within the nacelle to isolate that portion of the total engine system acoustic signature attributed to fan noise. The RAN design accomplished this by removing the stators that provided internal support to the nacelle. In its place, two external struts mounted to a two-axis positioning table located behind the tunnel wall provided the support. Nacelle-mounted lasers and a closed-loop control system provided the input to the table to maintain nacelle to fan concentricity as thermal and thrust loads displaced the strut-mounted fan. This unique design required extensive analysis and verification testing to ensure the safety of the fan model, propulsion simulator drive rig, and facility, along with experimental consistency of acoustic data obtained while using the RAN system. Initial testing was used to optimize the positioning system and resulted in concentricity errors of +/- 0.0031 in. in the horizontal direction and +0.0035/-0.0013 in, in the vertical direction. As a result of successful testing, the RAN system will be transitioned into other acoustic research programs at NASA Glenn Research Center.
    Keywords: Aircraft Propulsion and Power
    Type: NASA/TM-2001-210820 , NAS 1.15:210820 , E-12738 , AIAA Paper 2001-1058 , 39th Aerospace Sciences Meeting and Exhibit; Jan 08, 2001 - Jan 11, 2001; Reno, NV; United States
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