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  • Fluid Mechanics and Thermodynamics  (529)
  • Geophysics  (428)
  • Organic Chemistry  (391)
  • Engineering
  • 2000-2004  (955)
  • 1985-1989
  • 1950-1954  (395)
  • 2004  (487)
  • 2003  (468)
  • 1953  (395)
Collection
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  • 2000-2004  (955)
  • 1985-1989
  • 1950-1954  (395)
Year
  • 1
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    Biological networks: the tinkerer as an engineer (2003)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2003-09-27
    Description: This viewpoint comments on recent advances in understanding the design principles of biological networks. It highlights the surprising discovery of "good-engineering" principles in biochemical circuitry that evolved by random tinkering.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Alon, U -- New York, N.Y. -- Science. 2003 Sep 26;301(5641):1866-7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, Israel 76100. urialon@weizmann.ac.il〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/14512615" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Biochemical Phenomena ; Biochemistry ; *Biological Evolution ; *Biology ; DNA/metabolism ; Engineering ; *Models, Biological ; Proteins/metabolism ; Signal Transduction ; Systems Theory
    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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    Interdisciplinary research. Keck gives $40 million for academies initiative (2003)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2003-04-26
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Bhattacharjee, Yudhijit -- New York, N.Y. -- Science. 2003 Apr 25;300(5619):565.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/12714717" target="_blank"〉PubMed〈/a〉
    Keywords: *Academies and Institutes ; Engineering ; *Foundations ; Institute of Medicine (U.S.) ; *National Academy of Sciences (U.S.) ; *Research Support as Topic ; United States
    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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    Large Eddy Simulation of Flow in Turbine Cascades Using LESTool and UNCLE Codes (2004)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: During the period December 23,1997 and December August 31,2004, we accomplished the development of 2 CFD codes for DNS/LES/RANS simulation of turbine cascade flows, namely LESTool and UNCLE. LESTool is a structured code making use of 5th order upwind differencing scheme and UNCLE is a second-order-accuracy unstructured code. LESTool has both Dynamic SGS and Spalart's DES models and UNCLE makes use of URANS and DES models. The current report provides a description of methodologies used in the codes.
    Keywords: Fluid Mechanics and Thermodynamics
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  • 4
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    Bangui Anomaly (2004)
    In:  CASI
    Details
    Publication Date: 2013-08-29
    Description: Bangui anomaly is the name given to one of the Earth s largest crustal magnetic anomalies and the largest over the African continent. It covers two-thirds of the Central African Republic and therefore the name derives from the capitol city-Bangui that is also near the center of this feature. From surface magnetic survey data Godivier and Le Donche (1962) were the first to describe this anomaly. Subsequently high-altitude world magnetic surveying by the U.S. Naval Oceanographic Office (Project Magnet) recorded a greater than 1000 nT dipolar, peak-to-trough anomaly with the major portion being negative (figure 1). Satellite observations (Cosmos 49) were first reported in 1964, these revealed a 40nT anomaly at 350 km altitude. Subsequently the higher altitude (417-499km) POGO (Polar Orbiting Geomagnetic Observatory) satellite data recorded peak-to-trough anomalies of 20 nT these data were added to Cosmos 49 measurements by Regan et al. (1975) for a regional satellite altitude map. In October 1979, with the launch of Magsat, a satellite designed to measure crustal magnetic anomalies, a more uniform satellite altitude magnetic map was obtained. These data, computed at 375 km altitude recorded a -22 nT anomaly (figure 2). This elliptically shaped anomaly is approximately 760 by 1000 km and is centered at 6%, 18%. The Bangui anomaly is composed of three segments; there are two positive anomalies lobes north and south of a large central negative field. This displays the classic pattern of a magnetic anomalous body being magnetized by induction in a zero inclination field. This is not surprising since the magnetic equator passes near the center of this body.
    Keywords: Geophysics
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  • 5
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    Hubble Space Telescope Bi-Stem Thermal Shield Analyses (2004)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: The Hubble Space Telescope (HST) was launched April 24, 1990, and was deployed April 25 into low Earth orbit (LEO). It was soon discovered that the metal poles holding the solar arrays were expanding and contracting as the telescope orbited the Earth passing between the sunlight and the Earth s shadow. The expansion and contraction, although very small, was enough to cause the telescope to shake because of thermal-induced jitters, a detrimental effect when trying to take pictures millions of miles away. Therefore, the European Space Agency (ESA, the provider of the solar arrays) built new solar arrays (SA-11) that contained bi-stem thermal shields which insulated the solar array metal poles. These thermal shields were made of 2 mil thick aluminized-Teflon fluorinated ethylene propylene (FEP) rings fused together into a circular bellows shape. The new solar arrays were put on the HST during an extravehicular activity (EVA), also called an astronaut space walk, during the first servicing mission (SM1) in December 1993. An on-orbit photograph of the HST with the SA-11, and a close up of the bellows-like structure of the thermal shields is provided in Figure 1.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: Interm Summary Reports
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  • 6
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    Ancient Giant Basin/Aquifer System in the Arabia Region, Mars, and Its Influence on the Evolution of the Highland-Lowland Boundary (2004)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: Ancient geologic and hydrologic phenomena on Mars observed through the magnetic data provide windows to the ancient past through the younger Argyre and Hellas impacts, the northern plains basement and the rock materials that mantle the basement, and the Tharsis and Elysium magmatic complexes (recently referred to as superplumes). These signatures, coupled with highly degraded macrostructures (tectonic features that energetic planet during its embryonic development (0.5 Ga or so of activity) with an active dynamo and magnetosphere. One such window into the ancient past occurs northwest of the Hellas impact basin in Arabia Tern. Arabia Terra is one of the few water-rich equatorial regions of Mars, as indicated I through impact crater and elemental information. This region records many unique characteristics, including predominately Noachian materials, a highland-lowland boundary region that is distinct from other boundary regions, the presence of very few macrostructures when compared to the rest of the cratered highlands, the largest region of fretted terrain on Mars, outflow channels such as Mamers Valles that do not have obvious origins, and distinct albedo, thermal inertia, gravity, magnetic, and elemental signatures.
    Keywords: Geophysics
    Type: Workshop on Hemispheres Apart: The Origin and Modification of The Martian Crustal Dichotomy; 13-14; LPI-Contrib-1213
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  • 7
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    Survival of Amino Acids in Micrometeorites During Atmospheric Entry (2003)
    In:  Other Sources
    Details
    Publication Date: 2011-08-23
    Description: The delivery of amino acids by micrometeorites to the early Earth during the period of heavy bombardment could have been a significant source of the Earth's prebiotic amino acid inventory provided that these organic compounds survived atmospheric entry heating. To investigate the sublimation of amino acids from a micrometeorite analog at elevated temperature, grains from the CM-type carbonaceous chondrite Murchison were heated to 550 C inside a glass sublimation apparatus (SA) under reduced pressure. The sublimed residue that had collected on the cold finger of the SA after heating was analyzed for amino acids by HPLC. We found that when the temperature of the meteorite reached approx. 150 C, a large fraction of the amino acid glycine had vaporized from the meteorite, recondensed onto the end of the SA cold finger, and survived as the rest of the grains heated to 550 C. alpha-Aminoisobutryic acid and isovaline, which are two of the most abundant non-protein amino acids in Murchison, did not sublime from the meteorite and were completely destroyed during the heating experiment. Our experimental results suggest that sublimation of glycine present in micrometeorite grains may provide a way for this amino acid to survive atmospheric entry heating at temperatures less than 550 C; all other amino acids apparently are destroyed. Key Words: Amino acids-Exogenous delivery-Micrometeorites-Sublimation.
    Keywords: Geophysics
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  • 8
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    Freshwater Microbialites of Pavilion Lake, British Columbia, Canada: A Limnological Investigation (2004)
    In:  CASI
    Details
    Publication Date: 2017-10-02
    Description: Pavillion Lake is 5.7km long and an average of 0.8 km in width, and is located in Marble Canyon in the interior of British Columbia, Canada. It is a slightly alkaline, freshwater lake with a maximum-recorded depth of 65m. The basin walls of Pavilion Lake are lined with microbialite structures that are oriented perpendicularly to the shoreline, and which are found from depths of 5 meters to the bottom of the photic zone (light levels 1% of ambient; approximately 30m depth). These structures are speculated to have begun formation nearly 11,000 years ago, after the glacial retreat of the Cordilleran Ice Sheet. They are likely a distinctive assemblage of freshwater calcite microbialites, which display micromorphologies possibly related to the ancient Epiphyton and Girvanella classes of calcareous organosedimentary structures.
    Keywords: Geophysics
    Type: Second Conference on Early Mars: Geologic, Hydrologic, and Climatic Evolution and the Implications for Life; LPI-Contrib-1211
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  • 9
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    Studies of Rock Abrasion on Earth and Mars (2003)
    In:  CASI
    Details
    Publication Date: 2017-10-02
    Description: Many field studies have been conducted that document the morphology of ventifacts and the directionality of their features relative to current and past wind regimes. Field plots and wind tunnel studies have identified heights and particle concentrations above the surface where maximum abrasion occurs. However, as of yet, the rates and detailed methods by which rocks abrade and evolve into ventifacts are poorly documented and understood. This abstract addresses this gap in knowledge by interpreting controlled laboratory and field analog studies. We begin with an overview of the methods by which the wind tunnel experiments and field studies were done, followed by how the resulting data were analyzed and interpreted. A presentation of the results comes next, after which the implications for rock abrasion and ventifact formation on Earth and Mars are discussed. We show that initial rock shape and texture play important roles in determining both rate and style of abrasion, with steep-sided, rough rocks eroding the fastest but with intermediate-angled faces exhibiting the greatest shape change. Most rocks tend to evolve toward an equilibrium shape whose form is poorly conducive to further abrasion. Most rocks on Mars and in terrestrial ventifact localities never reach this mature state, with erosion ceasing or slowing down due to exhaustion of the sand supply and other factors.
    Keywords: Geophysics
    Type: Sixth International Conference on Mars; LPI-Contrib-1164
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  • 10
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    Geologic Evolution of Eastern Hellas, Mars: Styles and Timing of Volatile-driven Activity (2004)
    In:  CASI
    Details
    Publication Date: 2017-10-02
    Description: The east rim of the Hellas basin and the surrounding highlands comprise a geologically significant region for evaluating volatile abundance, volatile distribution and cycling, and potential changes in Martian environmental conditions. This region of the Martian surface exhibits landforms shaped by a diversity of geologic processes and has a well-preserved geologic record, with exposures of Noachian, Hesperian, and Amazonian units, as well as spans a wide range in both latitude and elevation due to the magnitude of Hellas basin. In addition, geologically contemporaneous volcanism and volatile-driven activity in the circum-Hellas highlands provide important ingredients for creating habitats for potential Martian life.
    Keywords: Geophysics
    Type: Second Conference on Early Mars: Geologic, Hydrologic, and Climatic Evolution and the Implications for Life; LPI-Contrib-1211
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  • 11
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    New Insights into the Geology of the Mars Pathfinder Landing Site from Spectral and Morphologic Analysis of the 12-Color Superpan Panorama (2003)
    In:  CASI
    Details
    Publication Date: 2017-10-02
    Description: New analyses of rocks and soils at the Mars Pathfinder landing site have been completed using the full Imager for Mars Pathfinder (IMP) 12- color SuperPan panorama. These revise early conclusions that rocks at the landing site are a single lithology coated only by windblown dust. We conclude instead that there is also a second lithology in addition to the dominant gray rock, and that it is consistent with highlands material excavated from beneath a thin veneer of northern plains; that many rocks have cemented coatings that formed during an early, probably wetter climate; and that young rocks excavated after coating formation ceased are mainly breccias or conglomerates.
    Keywords: Geophysics
    Type: Sixth International Conference on Mars; LPI-Contrib-1164
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  • 12
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    Coherent interannual and decadal variations inthe atmosphere-ocean system (2003)
    In:  Other Sources
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    Publication Date: 2018-06-08
    Description: We investigate the source of poleward propagating atmospheric zonal wind anomalies, originating at the equator and penetrating to high latitudes in both hemispheres in conjunction with ENSO [Dickey et al.,1992], and report the discovery of similar variability on decadal and longer timescales. Since atmospheric dissipation times are generally on the order of a month or less, we examine the ocean as a 'memory' source for these globally coherent anomalies. This hypothesis is substantiated by the observation of complementaryoscillation in the sea surface temperature (SST) field; further, we detect a robust decadal variability (~1012 yrs)in both the SST and contemporaneous atmospheric angular momentum (AAM) series. Analyzing GISST SST data beginning in 1902, we confirm this decadal mode and find signatures of longer (multidecadal) SST variability centered in the equatorial and North Pacific.
    Keywords: Geophysics
    Type: Geophysical Research Letters
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  • 13
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    NASA's Global Differential GPS System (2003)
    In:  Other Sources
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    Publication Date: 2018-06-08
    Keywords: Geophysics
    Type: European Geophysical Society; Nice; France
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  • 14
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    Large-scale global surface mass variations inferred from GPS (2003)
    In:  Other Sources
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    Publication Date: 2018-06-08
    Keywords: Geophysics
    Type: International Union of Geodesy and Geophysics (IUGG) 2003 Conference; Sapporo; Japan
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  • 15
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    Recent JPL results from GRACE (2003)
    In:  Other Sources
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    Publication Date: 2018-06-08
    Keywords: Geophysics
    Type: European Geophysical Society and American Geophysical Union Joint Assembly; Nice; France
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  • 16
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    A study of ozone variability and its connection with meridional transport in the northern Pacific lower stratosphere during summer 2002 (2004)
    In:  Other Sources
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    Publication Date: 2018-06-08
    Description: A preliminary study of the impact of the north-central Pacific circulation in the subtropical stratosphere on ozone variability locally observed by lidar is presented.
    Keywords: Geophysics
    Type: Journal of Geophysical Research; Volume 109; D11105-11118
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  • 17
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    Volcanic Activity at Tvashtar Catena, Io (2004)
    In:  CASI
    Details
    Publication Date: 2018-06-11
    Description: Tvashtar Catena (63 N, 120 W) is one of the most interesting features on Io. This chain of large paterae (caldera-like depressions) has exhibited highly variable volcanic activity in a series of observations. Tvashtar is the type example of a style of volcanism seen only at high latitudes, with short-lived Pele-type plumes and short-lived by intense thermal events. Evidence for a hot spot at Tvashtar was first detected in an eclipse observation in April 1997 (orbit G7) by the Solid State Imager (SSI) on the Galileo Spacecraft. Tvashtar was originally targeted for observation at higher resolution in the close flyby in November 1999 (I25) because of its interesting large-scale topography. There are relatively few but generally larger paterae at high latitudes on Io. I25 images revealed a 25 km long, 1-2 km high lava curtain via a pattern of saturation and bleeding in the CCD image, which requires very high temperatures.
    Keywords: Geophysics
    Type: Lunar and Planetary Science XXXV: Io, with a Dash of Titan; LPI-Contrib-1197
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  • 18
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    Global Distribution of Active Volcanism on Io as Known at the End of the Galileo Mission (2004)
    In:  CASI
    Details
    Publication Date: 2018-06-11
    Description: Hot spots are manifestations of Io s mechanism of internal heating and heat transfer. Therefore, the global distribution of hot spots and their power output has important implications for how Io is losing heat. The end of the Galileo mission is an opportune time to revisit studies of the distribution of hot spots on Io, and to investigate the distribution of their power output.
    Keywords: Geophysics
    Type: Lunar and Planetary Science XXXV: Io, with a Dash of Titan; LPI-Contrib-1197
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  • 19
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    Lava Lakes on Io: New Perspectives from Modeling (2004)
    In:  CASI
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    Publication Date: 2018-06-11
    Description: Ionian paterae are a class of volcanic feature that are characterized by irregular craters with steep walls, flat floors, and arcuate margins that may or may not exhibit nesting. Loki (310 W, 12 N) is Io's largest patera at approx.200 km in diameter (Figure 1), and may account for 15% of Io's total heat flow. Earth-based infrared data, as well as information collected using the Galileo Near-Infrared Mapping Spectrometer (NIMS) and the Photopolarimeter Radiometer (PPR) have been used to interpret Loki s eruption style. Debate continues over whether Loki s occasional (periodic or not) temperature increases are due to an overturning lava lake within the patera, or to an eruption of surface flows on the patera floor. Interpretation of model results and comparisons with active terrestrial lava lakes suggest that Loki behaves quite differently from active lava lakes on Earth, and that surface flows (rather than an overturning lava lake) are a more likely explanation of Loki's thermal brightening.
    Keywords: Geophysics
    Type: Lunar and Planetary Science XXXV: Io, with a Dash of Titan; LPI-Contrib-1197
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  • 20
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    Relationships Between Paterae, Mountains, and Hotspots on Io from a Global Database (2004)
    In:  CASI
    Details
    Publication Date: 2018-06-11
    Description: Now that the Galileo spacecraft s tour of the Jupiter system is over, we seek to integrate all available datasets in the hopes of understanding Io as completely as possible. We have compiled information about the morphologies and locations of paterae (volcano-tectonic depressions), mountains, and hotspots on Io in a single database. It is our hope that an analysis of the spatial and temporal relationships between these features will provide more indications of the nature of the crust of Io and the mechanisms leading to these features formation. Since Io s tidal heat escapes through its crust, more knowledge about the crust will lead to an understanding of internal processes, such as magma generation and delivery to the surface, and magnitude and orientation of internal stresses.
    Keywords: Geophysics
    Type: Lunar and Planetary Science XXXV: Io, with a Dash of Titan; LPI-Contrib-1197
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  • 21
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    Developing of a New Atmospheric Ionizing Radiation (AIR) Model (2003)
    In:  CASI
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    Publication Date: 2018-06-11
    Description: As a result of the research leading to the 1998 AIR workshop and the subsequent analysis, the neutron issues posed by Foelsche et al. and further analyzed by Hajnal have been adequately resolved. We are now engaged in developing a new atmospheric ionizing radiation (AIR) model for use in epidemiological studies and air transportation safety assessment. A team was formed to examine a promising code using the basic FLUKA software but with modifications to allow multiple charged ion breakup effects. A limited dataset of the ER-2 measurements and other cosmic ray data will be used to evaluate the use of this code.
    Keywords: Geophysics
    Type: Atmospheric Ionizing Radiation (AIR): Analysis, Results, and Lessons Learned From the June 1997 ER-2 Campaign; 370-375; NASA/CP-2003-212155
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  • 22
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    Enhancements in lower stratospheric CH3CN observed by the upper atmosphere research Sattellite Microwave Limb Sounder following boreal forest fires (2004)
    In:  Other Sources
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    Publication Date: 2018-06-08
    Description: On 25 August 1992, the Microwave Limb Sounder (MLS) on the Upper Atmosphere Research Satellite observed a significant enhancement in the abundance of lower stratospheric methyl cyanide (CH3CN) at 100??hPa (~16??km altitude) in a small region off the east coast of Florida.
    Keywords: Geophysics
    Type: Journal of Geophysical Research; Volume 109
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  • 23
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    Detecting features in seismic and geodetic data (2003)
    In:  Other Sources
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    Publication Date: 2018-06-08
    Keywords: Geophysics
    Type: 35th Symposium on the Interface: Computing Science and Statistics; Salt Lake City, UT; United States
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  • 24
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    Fram Strait sea ice outflow (2004)
    In:  Other Sources
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    Publication Date: 2018-06-08
    Description: We summarize 24 years (1978??2) of ice export estimates and examine, over a 9-year record, the associated variability in the time-varying upward-looking sonar (ULS) thickness distributions of the Fram Strait.
    Keywords: Geophysics
    Type: Journal of Geophysical Research; Volume 109; c09009-c01029
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  • 25
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    Data assimilation of ground GPG total electron content into a physics-based ionosheric model by use of the Kalman filter (2004)
    In:  Other Sources
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    Publication Date: 2018-06-08
    Description: A three-dimensional (3-D) Global Assimilative Ionospheric Model (GAIM) is currently being developed by a joint University of Southern California and Jet Propulsion Laboratory (JPL) team. To estimate the electron density on a global grid, GAIM uses a first-principles ionospheric physics model and the Kalman filter as one of its possible estimation techniques.
    Keywords: Geophysics
    Type: Radio science; Volume 39
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  • 26
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    Mesoscale Gravity Wave Variances from AMSU-A Radiances (2004)
    In:  Other Sources
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    Publication Date: 2018-06-11
    Description: A variance analysis technique is developed here to extract gravity wave (GW) induced temperature fluctuations from NOAA AMSU-A (Advanced Microwave Sounding Unit-A) radiance measurements. By carefully removing the instrument/measurement noise, the algorithm can produce reliable GW variances with the minimum detectable value as small as 0.1 K2. Preliminary analyses with AMSU-A data show GW variance maps in the stratosphere have very similar distributions to those found with the UARS MLS (Upper Atmosphere Research Satellite Microwave Limb Sounder). However, the AMSU-A offers better horizontal and temporal resolution for observing regional GW variability, such as activity over sub-Antarctic islands.
    Keywords: Geophysics
    Type: Geophysical Research Letters; Volume 31
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  • 27
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    Global Dayside Ionospheric Uplift and Enhancement Associated with Interplanetary Electric Fields (2004)
    In:  Other Sources
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    Publication Date: 2018-06-11
    Description: The interplanetary shock/electric field event of 5-6 November 2001 is analyzed using ACE interplanetary data. The consequential ionospheric effects are studied using GPS receiver data from the CHAMP and SAC-C satellites and altimeter data from the TOPEX/ Poseidon satellite. Data from ~100 ground-based GPS receivers as well as Brazilian Digisonde and Pacific sector magnetometer data are also used. The dawn-to-dusk interplanetary electric field was initially ~33 mV/m just after the forward shock (IMF BZ = -48 nT) and later reached a peak value of ~54 mV/m 1 hour and 40 min later (BZ = -78 nT). The electric field was ~45 mV/m (BZ = -65 nT) 2 hours after the shock. This electric field generated a magnetic storm of intensity DST = -275 nT. The dayside satellite GPS receiver data plus ground-based GPS data indicate that the entire equatorial and midlatitude (up to +/-50(deg) magnetic latitude (MLAT)) dayside ionosphere was uplifted, significantly increasing the electron content (and densities) at altitudes greater than 430 km (CHAMP orbital altitude). This uplift peaked ~2 1/2 hours after the shock passage. The effect of the uplift on the ionospheric total electron content (TEC) lasted for 4 to 5 hours. Our hypothesis is that the interplanetary electric field ''promptly penetrated'' to the ionosphere, and the dayside plasma was convected (by E x B) to higher altitudes. Plasma upward transport/convergence led to a ~55-60% increase in equatorial ionospheric TEC to values above ~430 km (at 1930 LT). This transport/convergence plus photoionization of atmospheric neutrals at lower altitudes caused a 21% TEC increase in equatorial ionospheric TEC at ~1400 LT (from ground-based measurements). During the intense electric field interval, there was a sharp plasma ''shoulder'' detected at midlatitudes by the GPS receiver and altimeter satellites. This shoulder moves equatorward from -54(deg) to -37(deg) MLAT during the development of the main phase of the magnetic storm. We presume this to be an ionospheric signature of the plasmapause and its motion. The total TEC increase of this shoulder is ~80%. Part of this increase may be due to a "superfountain effect." The dayside ionospheric TEC above ~430 km decreased to values ~45% lower than quiet day values 7 to 9 hours after the beginning of the electric field event. The total equatorial ionospheric TEC decrease was ~16%. This decrease occurred both at midlatitudes and at the equator. We presume that thermospheric winds and neutral composition changes produced by the storm-time Joule heating, disturbance dynamo electric fields, and electric fields at auroral and subauroral latitudes are responsible for these decreases.
    Keywords: Geophysics
    Type: Journal Of Geophysical Research (ISSN 0148-0227); Volume 109
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    Vortical Flow Prediction Using an Adaptive Unstructured Grid Method (2003)
    In:  CASI
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    Publication Date: 2018-06-28
    Description: A computational fluid dynamics (CFD) method has been employed to compute vortical flows around slender wing/body configurations. The emphasis of the paper is on the effectiveness of an adaptive grid procedure in "capturing" concentrated vortices generated at sharp edges or flow separation lines of lifting surfaces flying at high angles of attack. The method is based on a tetrahedral unstructured grid technology developed at the NASA Langley Research Center. Two steady-state, subsonic, inviscid and Navier-Stokes flow test cases are presented to demonstrate the applicability of the method for solving practical vortical flow problems. The first test case concerns vortex flow over a simple 65 delta wing with different values of leading-edge radius. Although the geometry is quite simple, it poses a challenging problem for computing vortices originating from blunt leading edges. The second case is that of a more complex fighter configuration. The superiority of the adapted solutions in capturing the vortex flow structure over the conventional unadapted results is demonstrated by comparisons with the wind-tunnel experimental data. The study shows that numerical prediction of vortical flows is highly sensitive to the local grid resolution and that the implementation of grid adaptation is essential when applying CFD methods to such complicated flow problems.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: Symposium on Advanced Flow Management. Part A: Vortex Flows and High Angle of Attack for Military Vehicles. Part B: Heat Transfer and Cooling in Propulsion and Power Systems; RTO-MP-069(I)-Pt-A-B
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    Forebody Aerodynamics of the F-18 High Alpha Research Vehicle with Actuated Forebody Strakes (2003)
    In:  CASI
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    Publication Date: 2018-06-28
    Description: Extensive pressure measurements and off-surface flow visualization were obtained on the forebody and strakes of the NASA F-18 High Alpha Research Vehicle (HARV) equipped with actuated forebody strakes. Forebody yawing moments were obtained by integrating the circumferential pressures on the forebody and strakes. Results show that large yawing moments can be generated with forebody strakes. At a 50 -angle-of-attack, deflecting one strake at a time resulted in a forebody yawing moment control reversal for small strake deflection angles. However, deflecting the strakes differentially about a 20 symmetric strake deployment eliminated the control reversal and produced a near linear variation of forebody yawing moment with differential strake deflection. At an angle of attack of 50 and for 0 and 20 symmetric strake deployments, a larger forebody yawing moment was generated by the forward fuselage (between the radome and the apex of the leading-edge extensions) than on the radome where the actuated forebody strakes were located. Cutouts on the flight vehicle strakes that were not on the wind tunnel models are believed to be responsible for deficits in the suction peaks on the flight radome pressure distributions and differences in the forebody yawing moments.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: Symposium on Advanced Flow Management. Part A: Vortex Flows and High Angle of Attack for Military Vehicles. Part B: Heat Transfer and Cooling in Propulsion and Power Systems; RTO-MP-069(I)-Pt-A-B
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    Cranked Arrow Wing (F-16XL-1) Flight Flow Physics with CFD Predictions at Subsonic and Transonic Speeds (2003)
    In:  CASI
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    Publication Date: 2018-06-28
    Description: The CFD modeling used has produced reasonably good global upper-surface pressure coefficient comparisons with measured flight data at both transonic and subsonic speeds at the angles of attack presented. Boundary layer comparisons showed the profiles to be reasonably well predicted inboard and under the primary vortex system. However, the secondary vortex profile was not well predicted either at the anticipated separation point or under the secondary vortex. Moreover, the flight data showed there to be a vortex/boundary-layer interaction that occurred in the vicinity of the secondary vortex. The spanwise distribution of local skin friction measured data was reasonably well predicted, especially away from the wing leading-edge. Lastly, predicted and measured flight-pressures, as well as flight-image data, for the F-16XL-1 airplane are now available via the World Wide Web.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: Symposium on Advanced Flow Management. Part A: Vortex Flows and High Angle of Attack for Military Vehicles. Part B: Heat Transfer and Cooling in Propulsion and Power Systems; RTO-MP-069(I)-Pt-A-B
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    In-Flight Flow Visualization Results of the F-106B with a Vortex Flap (2003)
    In:  CASI
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    Publication Date: 2018-06-28
    Description: Surface and off-surface flow visualization techniques were used to visualize the three-dimensional vortex flows on the F-106 aircraft with vortex flaps installed. Results at angles of attack between 9 degrees to 18 degrees and Mach numbers from 0.3 to 0.9 are presented. A smoke flow vapor screen technique was used to document leading-edge vortex paths and sizes, while an oil flow technique was employed to provide detailed information on reattachment and separation line locations and other flow details. Results were obtained for two vortex flap deflection angles, 30 degrees and 40 degrees. Flow visualization revealed the existence of a multiple vortex system that had not previously been seen in subscale tests or predicted for this configuration. The vortex flap generated a leading-edge vortex system that reattached near the flap hinge over a wide angle of attack range. In addition to the primary vortex, flow visualization revealed the presence of several distinct vortices which traced a path from the vortex flap and then over the wing.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: Symposium on Advanced Flow Management. Part A: Vortex Flows and High Angle of Attack for Military Vehicles. Part B: Heat Transfer and Cooling in Propulsion and Power Systems; RTO-MP-069(I)-Pt-A-B
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    Control of Interacting Vortex Flows at Subsonic and Transonic Speeds Using Passive Porosity (2003)
    In:  CASI
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    Publication Date: 2018-06-28
    Description: A wind tunnel experiment was conducted in the NASA Langley Research Center (LaRC) 8-Foot Transonic Pressure Tunnel (TPT) to determine the effects of passive surface porosity on vortex flow interactions about a general research fighter configuration at subsonic and transonic speeds. Flow-through porosity was applied to a wing leading-edge extension (LEX) mounted to a 65 deg cropped delta wing model to promote large nose-down pitching moment increments at high angles of attack. Porosity decreased the vorticity shed from the LEX, which weakened the LEX vortex and altered the global interactions of the LEX and wing vortices at high angles of attack. Six-component forces and moments and wing upper surface static pressure distributions were obtained at free-stream Mach numbers of 0.50, 0.85, and 1.20, Reynolds number of 2.5(10(exp 6)) per foot, angles of attack up to 30 deg, and angles of sideslip to +/- 8 deg. The off-surface flow field was visualized in selected cross-planes using a laser vapor screen flow visualization technique. Test data were obtained with a centerline vertical tail and with alternate twin, wing-mounted vertical fins having 0 deg and 30 deg cant angles. In addition, the porosity of the LEX was compartmentalized to determine the sensitivity of the vortex-dominated aerodynamics to the location and level of porosity applied to the LEX.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: Symposium on Advanced Flow Management. Part A: Vortex Flows and High Angle of Attack for Military Vehicles. Part B: Heat Transfer and Cooling in Propulsion and Power Systems; RTO-MP-069(I)-Pt-A-B
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    A decade of successful cooperation: what's next for the international GPS service? (2003)
    In:  Other Sources
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    Publication Date: 2018-06-08
    Keywords: Geophysics
    Type: International Union of Geodesy and Geophysics (IUGG) 2003 General Assembly; Sapporo; Japan
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    The international GPS service tracking network: enabling diverse studies and projects through international cooperation (2003)
    In:  Other Sources
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    Publication Date: 2018-06-08
    Keywords: Geophysics
    Type: XXIII General Assembly of the International Union of Geodesy and Geophysics; Sapporo; Japan
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    Search for Evaporite Minerals in Flaugergues Basin, Mars (2004)
    In:  CASI
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    Publication Date: 2018-06-11
    Description: Studies of Martian surface geomorphology and detection of near-surface water ice by the Mars Odyssey gamma ray spectrometer suggest that Mars may have had a water-rich past. While 2 to 5 wt.% of carbonate has been detected in the Martian dust [1,2], no spectral evidence for significant deposits of carbonates or sulfates has been found to date. Most investigations into Mars aqueous mineralogy have been global in scope with only a few regional studies (e.g., [3]). We are searching for localized deposits in putative lacustrine basins utilizing a basin flow model to identify basins with large drainage areas. Such basins are more likely to accumulate high concentrations of aqueous minerals than deep basins which drain only small regions.
    Keywords: Geophysics
    Type: Lunar and Planetary Science XXXV: Mars Mineralogy: Weathered and Dry; LPI-Contrib-1197
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    Thermal Emission Spectroscopy of Sulfates: Possible Hydrous Iron-Sulfate in the Soil at the MER-A Gusev Crater Landing Site (2004)
    In:  CASI
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    Publication Date: 2018-06-11
    Description: Sulfates are likely to be present on Mars as indicated by the sulfur abundances measured at the Viking and Pathfinder landing sites (approx. 5-10% by weight SO3) [1-3] and because of Mars strongly oxidizing environment. Telescopic observations of Mars tentatively identified weak sulfate bands in near infrared [4] and thermal infrared [5] data. The currently orbiting midinfrared instruments (TES, THEMIS) and the Mini-TES on the Mars Exploration Rover landers may enable a positive identification [6] and determination of the chemistry of the sulfates. Critically important to the identification of these minerals is the presence of their spectra in a spectral library. There exist approximately 370 sulfate-mineral species [7]. Sulfate minerals occur in volcanic, hydrothermal, evaporitic, and chemical-weathering environments.
    Keywords: Geophysics
    Type: Lunar and Planetary Science XXXV: Mars Mineralogy: Weathered and Dry; LPI-Contrib-1197
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    Geologic Evolution of the Martian Dichotomy and Plains Magnetization in the Ismenius Area of Mars (2004)
    In:  CASI
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    Publication Date: 2018-06-11
    Description: The global dichotomy divides the northern lowlands from the southern highlands, except where interrupted by relatively young volcanic provinces and impact basins. An elevation change of 2-4 km is typical across the dichotomy, and more than 6 km locally, over distances of several 100s km to as much as 1300 km [1,2]. A variety of exogenic and endogenic formation models have been proposed. Distinguishing between these models would help constrain the overall thermal evolution of the planet, possibly timing of core formation, and the associated mantle heat flux over time. A first step is to determine whether or not gravitational relaxation plays a role in modifying the boundary. Nimmo and Stevenson [3] examined 10 profiles across the dichotomy and used models of gravitational relaxation to conclude the relaxation has not occurred. In this study we begin by considering the geologic history in detail as inputs for modeling [4].
    Keywords: Geophysics
    Type: Lunar and Planetary Science XXXV: Mars Geophysics; LPI-Contrib-1197
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    Relaxation of the Martian Crustal Dichotomy Boundary in the Ismenius Region (2004)
    In:  CASI
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    Publication Date: 2018-06-11
    Description: The origin of the Martian crustal dichotomy remains a puzzle that when solved can provide an insight to the geological and geophysical evolution of Mars. In this study we model crustal relaxation in order to better constrain the original topographic shape, rheology, and temperature of the Martian crust. Our approach is to model the detailed geologic history of the Ismenius region of Mars, including slope, strain, and timing of faulting [1]. This region may contain the best preserved section of the dichotomy boundary as it is relatively unaffected by large impacts and erosion. So far the only study Martian crustal relaxation [2] suggests that the original topographic shape of the dichotomy is preserved. However, in this area strain from faulting implies at least some relaxation [1].
    Keywords: Geophysics
    Type: Lunar and Planetary Science XXXV: Mars Geophysics; LPI-Contrib-1197
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    Asymmetric Base-Bleed Effect on Aerospike Plume-Induced Base-Heating Environment (2004)
    In:  CASI
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    Publication Date: 2018-06-12
    Description: A computational heat transfer design methodology was developed to study the dual-engine linear aerospike plume-induced base-heating environment during one power-pack out, in ascent flight. It includes a three-dimensional, finite volume, viscous, chemically reacting, and pressure-based computational fluid dynamics formulation, a special base-bleed boundary condition, and a three-dimensional, finite volume, and spectral-line-based weighted-sum-of-gray-gases absorption computational radiation heat transfer formulation. A separate radiation model was used for diagnostic purposes. The computational methodology was systematically benchmarked. In this study, near-base radiative heat fluxes were computed, and they compared well with those measured during static linear aerospike engine tests. The base-heating environment of 18 trajectory points selected from three power-pack out scenarios was computed. The computed asymmetric base-heating physics were analyzed. The power-pack out condition has the most impact on convective base heating when it happens early in flight. The source of its impact comes from the asymmetric and reduced base bleed.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: Journal of Propulsion and Power (ISSN 0748-4658); Volume 20; No. 3; 385-393
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    Global variability of precipitation according to the Tropical Rainfall Measuring Mission (2004)
    In:  Other Sources
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    Publication Date: 2018-06-11
    Description: Numerous studies have documented the effect of El Nino-Southern Oscillation (ENSO) on rainfall in many regions of the globe. The question of whether ENSO is the single most important factor in interannual rainfall variability has received less attention, mostly because the kind of data that would be required to make such an assessment were simply not available. Until 1979 the evidence linking El Nino with changes in rainfall around the world came from rain gauges measuring precipitation over land masses and a handful of islands. From 1980 until the launch of the Tropical Rainfall Measuring Mission (TRMM) in November 1997 the remote sensing evidence was confined to ocean rainfall because of the very poor sensitivity of the instruments over land. In this paper we summarize the results of a principal component analysis of TRMM's 60-month (January 1998 to December 2002) global land and ocean remote-sensing record of monthly rainfall accumulations. Contrary to the first principal component of the rainfall itself, the first three indices of the anomaly are most sensitive to precipitation over the ocean rather than over the land. With the help of archived surface station data the first TRMM rain anomaly index is extended back several decades. Comparison of the extended index with the Southern Oscillation Index confirms that the first principal component of the rainfall anomaly is strongly correlated with the ENSO indices.
    Keywords: Geophysics
    Type: Journal of Geophysical Research; Volume 109; D17103
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    Microfabrication and Test of a Three-Dimensional Polymer Hydro-focusing Unit for Flow Cytometry Applications (2004)
    In:  CASI
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    Publication Date: 2018-06-11
    Description: This paper details a novel three-dimensional (3D) hydro-focusing micro cell sorter for micro flow cytometry applications. The unit was microfabricated by means of SU-8 3D lithography. The 3D microstructure for coaxial sheathing was designed, microfabricated, and tested. Three-dimensional hydro-focusing capability was demonstrated with an experiment to sort labeled tanned sheep erythrocytes (red blood cells). This polymer hydro-focusing microstructure is easily microfabricated and integrated with other polymer microfluidic structures.
    Keywords: Fluid Mechanics and Thermodynamics
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    A Review of the Match Technique as Applied to AASE-2/EASOE and SOLVE/THESEO 2000 (2004)
    In:  CASI
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    Publication Date: 2018-06-06
    Description: We apply the GSFC trajectory model with a series of ozonesondes to derive ozone loss rates in the lower stratosphere for the AASE-2/EASOE mission (January - March 1992) and for the SOLVE/THESEO 2000 mission (January - March 2000) in an approach similar to Match. Ozone loss rates are computed by comparing the ozone concentrations provided by ozonesondes launched at the beginning and end of the trajectories connecting the launches. We investigate the sensitivity of the Match results on the various parameters used to reject potential matches in the original Match technique and conclude that only a filter based on potential vorticity changes along the calculated back trajectory seems necessary. Our study also demonstrates that calculated ozone loss rates can vary by up to a factor of two depending upon the precise trajectory paths calculated for each trajectory. As a result an additional systematic error might need to be added to the statistical uncertainties published with previous Match results. The sensitivity to the trajectory path is particularly pronounced in the month of January, the month during which the largest ozone loss rate discrepancies between photochemical models and Match are found. For most of the two study periods, our ozone loss rates agree with those previously published. Notable exceptions are found for January 1992 at 475 K and late February/early March 2000 at 450 K, both periods during which we find less loss than the previous studies. Integrated ozone loss rates in both years compare well with those found in numerous other studies and in a potential vorticity/potential temperature approach shown previously and in this paper. Finally, we suggest an alternate approach to Match using trajectory mapping that appears to more accurately reflect the true uncertainties associated with Match and reduces the dependence upon filters that may bias the results of Match through the rejection of greater than or equal to 80% of the matched sonde pairs and 〉99% of matched observations.
    Keywords: Geophysics
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    Interannual Variability in Intercontinental Transport (2003)
    In:  CASI
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    Publication Date: 2018-06-06
    Description: We have investigated the importance of intercontinental transport using source-receptor relationship. A global radon-like and seven regional tracers were used in three-dimensional model simulations to quantify their contributions to column burdens and vertical profiles at world-wide receptors. Sensitivity of these contributions to meteorological input was examined using different years of meteorology in two atmospheric simulations. Results show that Asian emission influences tracer distributions in its eastern downwind regions extending as far as Europe with major contributions in mid- and upper troposphere. On the western and eastern sides of the US, Asian contribution to annual average column burdens are 37% and 5% respectively with strong monthly variations. At an altitude of 10 km, these contributions are 75% and 25% respectively. North American emissions contribute more than 15% to annual average column burden and about 50% at 8 km altitude over the European region. Contributions from tropical African emissions are wide-spread in both the hemispheres. Differences in meteorological input cause non-uniform redistribution of tracer mass throughout the troposphere at all receptors. We also show that in model-model and model-data comparison, correlation analysis of tracer's spatial gradients provides an added measure of model's performance.
    Keywords: Geophysics
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    Mesospheric Non-Migrating Tides Generated With Planetary Waves: II Influence of Gravity Waves (2003)
    In:  CASI
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    Publication Date: 2018-06-06
    Description: We demonstrated that, in our model, non-linear interactions between planetary waves (PW) and migrating tides could generate in the upper mesosphere non-migrating tides with amplitudes comparable to those observed. The Numerical Spectral Model (NSM) we employ incorporates Hines Doppler Spread Parameterization for small-scale gravity waves (GW), which affect in numerous ways the dynamics of the mesosphere. The latitudinal (seasonal) reversals in the temperature and zonal circulation, which are largely caused by GWs (Lindzen, 198l), filter the PWs and contribute to the instabilities that generate the PWs. The PWs in turn are amplified by the momentum deposition of upward propagating GWs, as are the migrating tides. The GWs thus affect significantly the migrating tides and PWs, the building blocks of non-migrating tides. In the present paper, we demonstrate that GW filtering also contributes to the non-linear coupling between PWs and tides. Two computer experiments are presented to make this point. In one, we simply turn off the GW source to show the effect. In the second case, we demonstrate the effect by selectively suppressing the momentum source for the m = 0 non-migrating tides.
    Keywords: Geophysics
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    Mesospheric Non-Migrating Tides Generated With Planetary Waves (2003)
    In:  CASI
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    Publication Date: 2018-06-06
    Description: We discuss results from a modeling study with our Numerical Spectral Model (NSM) that specifically deals with the non-migrating tides generated in the mesosphere. The NSM extends from the ground to the thermosphere, incorporates Hines' Doppler Spread Parameterization for small-scale gravity waves (GWs), and it describes the major dynamical features of the atmosphere including the wave driven equatorial oscillations (QBO and SAO), and the seasonal variations of tides and planetary waves. Accounting solely for the excitation sources of the solar migrating tides, the NSM generates through dynamical interactions also non-migrating tides in the mesosphere that are comparable in magnitude to those observed. Large non-migrating tides are produced in the diurnal and semi-diurnal oscillations for the zonal mean (m = 0) and in the semidiurnal oscillation for m = 1. In general, significant eastward and westward propagating tides are generated for all the zonal wave numbers m = 1 to 4. To identify the cause, the NSM is run without the solar heating for the zonal mean (m = 0), and the amplitudes of the resulting non-migrating tides are then negligibly small. In this case, the planetary waves are artificially suppressed, which are generated in the NSM through instabilities. This leads to the conclusion that the non-migrating tides are generated through non-linear interactions between planetary waves and migrating tides, as Forbes et al. and Talaat and Liberman had proposed. In an accompanying paper, we present results from numerical experiments, which indicate that gravity wave filtering contributes significantly to produce the non-linear coupling that is involved.
    Keywords: Geophysics
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    A Systematic Global Mapping of the Radiation Field at Aviation Altitudes (2003)
    In:  CASI
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    Publication Date: 2018-06-06
    Description: This paper presents early results from aircraft measurements made by a Low-LET Radiation Spectrometer (LoLRS), as part of a long-range effort to study the complex dynamics of the atmospheric radiation field. For this purpose, a comprehensive data base is being generated to enable a multivariable global mapping (and eventually modeling) of doses and Linear-Energy-Transfer (LET) spectra at aviation altitudes. To accomplish this, a methodical collection of data from the LoLRS (and other instruments), is planned over extended periods of time, in a manner that complements some previous isolated and sporadic measurements by other workers, with the objective to generate a detailed long-range description of the cosmic-ray induced particle environment and to study its variability and dependence on atmospheric thickness, magnetic latitude, L-shell or rigidity, space weather, solar particle events, solar cycle effects, magnetic field variation, diurnal and seasonal effects, and atmospheric weather. Analysis of initial data indicates that the dose is rising with increasing altitude and increasing magnetic latitude. Comparison of total doses with predictions is in good agreement.
    Keywords: Geophysics
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    Refinement of the ICRF (2004)
    In:  CASI
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    Publication Date: 2018-06-06
    Description: Since the ICRF was generated in 1995, VLBI modeling and estimation, data quality: source position stability analysis, and supporting observational programs have improved markedly. There are developing and potential applications in the areas of space navigation Earth orientation monitoring and optical astrometry from space that would benefit from a refined ICRF with enhanced accuracy, stability and spatial distribution. The convergence of analysis, focused observations, and astrometric needs should drive the production of a new realization in the next few years.
    Keywords: Geophysics
    Type: International VLBI Service for Geodesy and Astrometry 2004 General Meeting Proceedings; 337-340; NASA/CP-2004-212255
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    VLBI2010: Networks and Observing Strategies (2004)
    In:  CASI
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    Publication Date: 2018-06-06
    Description: The Observing Strategies Sub-group of IVS's Working Group 3 has been tasked with producing a vision for the following aspects of geodetic VLBI: antenna-network structure and observing strategies; source strength/structure/distribution; frequency bands, RFI; and field system and scheduling. These are high level considerations that have far reaching impact since they significantly influence performance potential and also constrain requirements for a number of other \VG3 sub-groups. The paper will present the status of the sub-group's work on these topics.
    Keywords: Geophysics
    Type: International VLBI Service for Geodesy and Astrometry 2004 General Meeting Proceedings; 60-64; NASA/CP-2004-212255
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    Living with a Star: New Opportunities in Sun-Climate Research (2003)
    In:  CASI
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    Publication Date: 2018-06-06
    Description: Enormous advances have been made in the last quarter century in all of these needed areas, covering the two essential halves of the Sun-Climate question: in what we know of solar variations and, equally important, in what we know of the climate system and of climatic changes. These research achievements allow us to examine all aspects of the question more directly and quantitatively than was ever possible before, and in the brighter light and more objective context of other known or suspected climate change mechanisms, including human-induced global greenhouse warming. Brief summaries of present status and current understanding are given below for nine facets of Sun-Climate science in which major progress has been made in recent years. At the same time it will be seen that in every instance, significant elements of uncertainty still remain, Some of the most important of these unanswered questions are considered later, in Section IV.
    Keywords: Geophysics
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    A Standard Atmosphere of the Antarctic Plateau (2004)
    In:  CASI
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    Publication Date: 2018-06-06
    Description: Climate models often rely on standard atmospheres to represent various regions; these broadly capture the important physical and radiative characteristics of regional atmospheres, and become benchmarks for simulations by researchers. The high Antarctic plateau is a significant region of the earth for which such standard atmospheres are as yet unavailable. Moreover, representative profiles from atmospheres over other regions of the planet, including &om the northern high latitudes, are not comparable to the atmosphere over the Antarctic plateau, and are therefore only of limited value as substitutes in climate models. Using data from radiosondes, ozonesondes and satellites along with other observations from South Pole station, typical seasonal atmospheric profiles for the high plateau are compiled. Proper representations of rapidly changing ozone concentrations (during the ozone hole) and the effect of surface elevation on tropospheric temperatures are discussed. The differences between standard profiles developed here and the most similar standard atmosphere that already exists - namely, the Arctic Winter profile - suggest that these new profiles will be extremely useful to make accurate representations of the atmosphere over the high plateau.
    Keywords: Geophysics
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    Satellite Detection of the Convection Generated Stresses in Earth (2003)
    In:  CASI
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    Publication Date: 2018-06-06
    Description: We review research developments on satellite detection of the convection generated stresses in the Earth for seismic hazard assessment and Earth resource survey. Particular emphasis is laid upon recent progress and results of stress calculations from which the origin and evolution of the tectonic features on Earth's surface can be scientifically addressed. An important aspect of the recent research development in tectonic stresses relative to earthquakes is the implications for earthquake forecasting and prediction. We have demonstrated that earthquakes occur on the ring of fire around the Pacific in response to the tectonic stresses induced by mantle convection. We propose a systematic global assessment of the seismic hazard based on variations of tectonic stresses in the Earth as observed by satellites. This space geodynamic approach for assessing the seismic hazard is unique in that it can pinpoint the triggering stresses for large earthquakes without ambiguities of geological structures, fault geometries, and other tectonic properties. Also, it is distinct from the probabilistic seismic hazard assessment models in the literature, which are based only on extrapolations of available earthquake data.
    Keywords: Geophysics
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    Column Closure Studies of Lower Tropospheric Aerosol and Water Vapor During ACE-Asia Using Airborne Sunphotometer, Airborne In-Situ and Ship-Based Lidar Measurements (2003)
    In:  CASI
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    Publication Date: 2018-06-06
    Description: We assess the consistency (closure) between solar beam attenuation by aerosols and water vapor measured by airborne sunphotometry and derived from airborne in-situ, and ship-based lidar measurements during the April 2001 Asian Pacific Regional Aerosol Characterization Experiment (ACE-Asia). The airborne data presented here were obtained aboard the Twin Otter aircraft. Comparing aerosol extinction o(550 nm) from four different techniques shows good agreement for the vertical distribution of aerosol layers. However, the level of agreement in absolute magnitude of the derived aerosol extinction varied among the aerosol layers sampled. The sigma(550 nm) computed from airborne in-situ size distribution and composition measurements shows good agreement with airborne sunphotometry in the marine boundary layer but is considerably lower in layers dominated by dust if the particles are assumed to be spherical. The sigma(550 nm) from airborne in-situ scattering and absorption measurements are about approx. 13% lower than those obtained from airborne sunphotometry during 14 vertical profiles. Combining lidar and the airborne sunphotometer measurements reveals the prevalence of dust layers at altitudes up to 10 km with layer aerosol optical depth (from 3.5 to 10 km altitude) of approx. 0.1 to 0.2 (500 nm) and extinction-to-backscatter ratios of 59-71 sr (523 nm). The airborne sunphotometer aboard the Twin Otter reveals a relatively dry atmosphere during ACE- Asia with all water vapor columns less than 1.5 cm and water vapor densities w less than 12 g/cu m. Comparing layer water vapor amounts and w from the airborne sunphotometer to the same quantities measured with aircraft in-situ sensors leads to a high correlation (r(sup 3)=0.96) but the sunphotometer tends to underestimate w by 7%.
    Keywords: Geophysics
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    Thin-Film Ceramic Thermocouples Fabricated and Tested (2004)
    In:  CASI
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    Publication Date: 2018-06-05
    Description: The Sensors and Electronics Technology Branch of the NASA Glenn Research Center is developing thin-film-based sensors for surface measurement in propulsion system research. Thin-film sensors do not require special machining of the components on which they are mounted, and they are considerably thinner than wire- or foil-based sensors. One type of sensor being advanced is the thin-film thermocouple, specifically for applications in high-temperature combustion environments. Ceramics are being demonstrated as having the potential to meet the demands of thin-film thermocouples in advanced aerospace environments. The maximum-use temperature of noble metal thin-film thermocouples, 1500 C (2700 F), may not be adequate for components used in the increasingly harsh conditions of advanced aircraft and next-generation launch vehicles. Ceramic-based thermocouples are known for their high stability and robustness at temperatures exceeding 1500 C, but are typically in the form of bulky rods or probes. As part of ASTP, Glenn's Sensors and Electronics Technology Branch is leading an in-house effort to apply ceramics as thin-film thermocouples for extremely high-temperature applications as part of ASTP. Since the purity of the ceramics is crucial for the stability of the thermocouples, Glenn's Ceramics Branch and Case Western Reserve University are developing high-purity ceramic sputtering targets for fabricating high-temperature sensors. Glenn's Microsystems Fabrication Laboratory, supported by the Akima Corporation, is using these targets to fabricate thermocouple samples for testing. The first of the materials used were chromium silicide (CrSi) and tantalum carbide (TaC). These refractory materials are expected to survive temperatures in excess of 1500 C. Preliminary results indicate that the thermoelectric voltage output of a thin-film CrSi versus TaC thermocouple is 15 times that of the standard type R (platinum-rhodium versus platinum) thermocouple, producing 20 mV with a 200 C temperature gradient. The photograph on the left shows the CrSi-TaC thermocouple in a test fixture at Glenn, and the resulting output signal is shown on the right. The temperature differential across the sample, from the center of the sample inside the oven to the sample mount outside the oven, is measured using a type R thermocouple on the sample.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: Research and Technology 2003; NASA/TM-2004-212729
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    Direct Simulation of Evolution and Control of Nonlinear Instabilities in Attachment-Line Boundary Layers (2004)
    In:  CASI
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    Publication Date: 2018-06-05
    Description: The unsteady, incompressible Navier-Stokes equations are used for the direct numerical simulation (DNS) of spatially evolving disturbances in a three-dimensional (3-D) attachment-line boundary layer. Two-dimensional (2-D) disturbances are introduced either by forcing at the in ow or by harmonic-source generators at the wall; 3-D disturbances are introduced by harmonic-source generators at the wall. The DNS results are in good agreement with both 2-D non-parallel theory (for small-amplitude disturbances) and weakly nonlinear theory (for finite-amplitude disturbances), which validates the two theories. The 2-D DNS results indicate that nonlinear disturbance growth occurs near branch II of the neutral stability curve; however, steady suction can be used to stabilize this disturbance growth. For 3-D instabilities that are generated o the attachment line, spreading both toward and away from the attachment line causes energy transfer to the attachment-line and downstream instabilities; suction stabilizes these instabilities. Furthermore, 3-D instabilities are more stable than 2-D or quasi-2-D instabilities.
    Keywords: Fluid Mechanics and Thermodynamics
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    Textbook Multigrid Efficiency for the Steady Euler Equations (2004)
    In:  CASI
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    Publication Date: 2018-06-05
    Description: A fast multigrid solver for the steady incompressible Euler equations is presented. Unlike time-marching schemes, this approach uses relaxation of the steady equations. Application of this method results in a discretization that correctly distinguishes between the advection and elliptic parts of the operator, allowing efficient smoothers to be constructed. Solvers for both unstructured triangular grids and structured quadrilateral grids have been written. Computations for channel flow and flow over a nonlifting airfoil have computed. Using Gauss-Seidel relaxation ordered in the flow direction, textbook multigrid convergence rates of nearly one order-of-magnitude residual reduction per multigrid cycle are achieved, independent of the grid spacing. This approach also may be applied to the compressible Euler equations and the incompressible Navier-Stokes equations.
    Keywords: Fluid Mechanics and Thermodynamics
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    Analysis of a Circular Composite Disk Subjected to Edge Rotations and Hydrostatic Pressure (2004)
    In:  CASI
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    Publication Date: 2018-06-12
    Description: The structural analysis results for a graphite/epoxy quasi-isotropic circular plate subjected to a forced rotation at the boundary and pressure is presented. The analysis is to support a specialized material characterization test for composite cryogenic tanks. Finite element models were used to ensure panel integrity and determine the pressure necessary to achieve a predetermined equal biaxial strain value. The displacement results due to the forced rotation at the boundary led to a detailed study of the bending stiffness matrix [D]. The variation of the bending stiffness terms as a function of angular position is presented graphically, as well as, an illustrative technique of considering the laminate as an I-beam.
    Keywords: Fluid Mechanics and Thermodynamics
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    Droplet Combustion in a Slow Convective Flow (2003)
    In:  CASI
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    Publication Date: 2018-06-06
    Description: The influences of slow convective flow on droplet combustion, particularly in the low Reynolds number regime, have received very little attention in the past. Most studies in the literature are semi-empirical in nature and they were motivated by spray combustion applications in the moderate to high Reynolds number regime. None of the limited number of fundamental theoretical studies applicable to low Reynolds numbers have been verified by rigorous experimental data. Moreover, many unsteady phenomena associated with fluid-dynamic unsteadiness, such as impulsive starting or stopping of a burning droplet, or flow acceleration/deceleration effects, have not been investigated despite their importance in practical applications. In this study we investigate the effects of slow convection on droplet burning dynamics both experimentally and theoretically. The experimental portion of the study involves both ground-based experiments in the drop towers and future flight experiments on board the International Space Station. Heptane and methanol are used as test fuels, and this choice complements the quiescent-environment studies of the Droplet Combustion Experiment (DCE). An analytical model that employs the method of matched asymptotic expansions and uses the ratio of the convective velocity far from the droplet to the Stefan velocity at its surface as the small parameter for expansion has also been developed as a part of this investigation. Results from the ground-based experiments and comparison with the analytical model are presented in this report.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: Seventh International Workshop on Microgravity Combustion and Chemically Reacting Systems; 157-160; NASA/CP-2003-212376/REV1
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    Report of the Stability and Dynamics Session (2003)
    In:  CASI
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    Publication Date: 2018-06-06
    Description: Important issues: Mass gauging; Stability dynamics of disconnected capillary surfaces; Slow capillary driven flow (i.e. wicking); Long-term material property evolution in micro-g; Dumping problem with freezing of dump lines.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: Results of the Workshop on Two-Phase Flow, Fluid Stability and Dynamics: Issues in Power, Propulsion, and Advanced Life Support Systems; 39-43; NASA/TM-2003-212598
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    Advances in High Performance Computational Methods for Large Scale Fluid/Structure Interaction (2003)
    In:  CASI
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    Publication Date: 2018-06-06
    Description: The objective of this viewgraph presentation is to present a summary of computational methods developed at Ames Research Center for large scale fluid/structure interaction.
    Keywords: Fluid Mechanics and Thermodynamics
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    Report on Multiphase Flow Panel (2003)
    In:  CASI
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    Publication Date: 2018-06-06
    Description: This paper presents viewgraphs on a multiphase flow panel. The topics include: 1) Discussion of Priorities; 2) Critical Issues Reduced Gravity Instabilities; 3) Severely Limiting Phase Separation; 4) Severely-Limiting Phase Change; 5) Enhancements; 6) Awareness Instabilities; 7) Awareness; 8) Methods of Resolution; 9) 2008 Space Flight; 10) 2003-2008 Ground-Based Microgravity Facilities; 11) 2003-2008 Other; 12) 2009-2015 Space Flight; 13) 2009-2015 Ground-Based Microgravity Facilities; 14) 2009-2015 Other; and 15) 2016.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: Results of the Workshop on Two-Phase Flow, Fluid Stability and Dynamics: Issues in Power, Propulsion, and Advanced Life Support Systems; 29-38; NASA/TM-2003-212598
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    Multiphase Flow in Power and Propulsion Workshop Fluid Stability and Dynamics Workshop: Overview (2003)
    In:  CASI
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    Publication Date: 2018-06-06
    Description: The short term purpose of this research is to present a research plan and a roadmap developed for strategic research for the Office of Biological and Physical Research and the long term purpose is to conduct necessary ground-based and space-flight low gravity experiments, complemented by analyses, resulting in a documented framework for parameter prediction of needed by designers. This paper is presented in viewgraph form.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: Results of the Workshop on Two-Phase Flow, Fluid Stability and Dynamics: Issues in Power, Propulsion, and Advanced Life Support Systems; 201-207; NASA/TM-2003-212598
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    A Study of the Impact of Variations on Aerodynamic Flow in Gas Turbine Engines via Monte-Carlo Simulations (2003)
    In:  CASI
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    Publication Date: 2018-06-06
    Description: The unsteady compressible inviscid flow is characterized by the conservations of mass, momentum, and energy; or simply the Euler equations. In this paper, a study of the subsonic one-dimensional Euler equations with local preconditioning is presented with a modal analysis approach. Specifically, this study investigates the behavior of airflow in a gas turbine engine using the specified conditions at the inflow and outflow boundaries of the compressor, combustion chamber, and turbine, under the impact of variations in pressure, velocity, temperature, and density at low Mach numbers. Two main questions that motivate this research are: 1) Is there any aerodynamic problem with the existing gas turbine engines that could impact aircraft performance? 2) If yes, what aspect of a gas turbine engine could be improved via design to alleviate that impact and to optimize aircraft performance. This paper presents an initial attempt to the flow behavior in terms (perturbation) using simulation outputs from a customer-deck model obtained from Pratt&Whitney, (i.e., pressure, temperature, velocity, density) about their mean states at the inflow and outflow boundaries of the compressor, combustion chamber, and turbine. Flow behavior is analyzed for the high pressure compressor and combustion chamber employing the conditions on their left and right boundaries. In the same fashion, similar analyses are carried out for the high and low-pressure turbines. In each case, the eigenfrequencies that are obtained for different boundary conditions are examined closely based on their probabilistic distributions, a result of a Monte Carlo 10,000-sample simulation. Furthermore, the characteristic waves and eave response are analyzed and contrasted among different cases, with and without preconditioners. The results reveal the existence of flow instabilities due to the combined effect of variations and excessive pressures; which are clearly the case in the combustion chamber and high-pressure turbine. Finally a discussion is presented on potential impacts of the instabilities and what can be improved via design to alleviate them for a better aircraft performance.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: IEEE Aerospace Conference; Big Sky, MT; United States
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    Comparison of Artificial Compressibility Methods (2004)
    In:  CASI
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    Publication Date: 2018-06-06
    Description: Various artificial compressibility methods for calculating the three-dimensional incompressible Navier-Stokes equations are compared. Each method is described and numerical solutions to test problems are conducted. A comparison based on convergence behavior, accuracy, and robustness is given.
    Keywords: Fluid Mechanics and Thermodynamics
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    An Experimental Study of Synthetic Jets from Rectangular Orifices (2003)
    In:  CASI
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    Publication Date: 2018-06-06
    Description: During the past two summers Professor Milanovic conducted Wind tunnel experiments on steady jets-in-cross-flow and synthetic jets. In her anticipated visit during the upcoming summer, she will continue and complete the research on synthetic jets involving 2-dimensional orifices of different aspect ratio as well as inclined slots. In addition, experiments will be conducted on pulsatile jets-in-cross-flow. The pulsation will be provided via an oscillating valve at controllable frequencies. The experiment will involve mainly hot-wire anemometer measurements in the low-speed wind tunnel. Overall goal will be to obtain database and investigate flow control strategies. The research will be of fundamental nature.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: NASA-OAI Collaborative Aerospace Research and Fellowship Program; 16-20
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    Flow Boiling Critical Heat Flux in Reduced Gravity (2004)
    In:  CASI
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    Publication Date: 2018-06-06
    Description: This study provides systematic method for reducing power consumption in reduced gravity systems by adopting minimum velocity required to provide adequate CHF and preclude detrimental effects of reduced gravity . This study proves it is possible to use existing 1 ge flow boiling and CHF correlations and models to design reduced gravity systems provided minimum velocity criteria are met
    Keywords: Fluid Mechanics and Thermodynamics
    Type: Strategic Research to Enable NASA's Exploration Missions Conference and Workshop: Presentations, Volume 1; 710-737; NASA/CP-2004-213205/VOL1
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    Phase Change (2004)
    In:  CASI
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    Publication Date: 2018-06-06
    Description: Recent workshops to define strategic research on critical issues in microgravity fluids and transport phenomena in support of mission orientated needs of NASA and many technical conferences over the years in support of fundamental research targeting NASA's long range missions goal have identified several phase change processes needed to design advanced space and planetary based systems for long duration operations Recommendation noted that phase change processes are profoundly affected by gravitational environment.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: Strategic Research to Enable NASA's Exploration Missions Conference and Workshop: Presentations, Volume 1; 255-268; NASA/CP-2004-213205/VOL1
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    Fixed Packed Bed Reactors in Reduced Gravity (2004)
    In:  CASI
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    Publication Date: 2018-06-06
    Description: We present experimental data on flow pattern transitions, pressure drop and flow characteristics for cocurrent gas-liquid flow through packed columns in microgravity. The flow pattern transition data indicates that the pulse flow regime exists over a wider range of gas and liquid flow rates under microgravity conditions compared to 1-g and the widely used Talmor map in 1-g is not applicable for predicting the transition boundaries. A new transition criterion between bubble and pulse flow in microgravity is proposed and tested using the data. Since there is no static head in microgravity, the pressure drop measured is the true frictional pressure drop. The pressure drop data, which has much smaller scatter than most reported 1-g data clearly shows that capillary effects can enhance the pressure drop (especially in the bubble flow regime) as much as 200% compared to that predicted by the single phase Ergun equation. The pressure drop data are correlated in terms of a two-phase friction factor and its dependence on the gas and liquid Reynolds numbers and the Suratman number. The influence of gravity on the pulse amplitude and frequency is also discussed and compared to that under normal gravity conditions. Experimental work is planned to determine the gas-liquid and liquid-solid mass transfer coefficients. Because of enhanced interfacial effects, we expect the gas-liquid transfer coefficients kLa and kGa (where a is the gas-liquid interfacial area) to be higher in microgravity than in normal gravity at the same flow conditions. This will be verified by gas absorption experiments, with and without reaction in the liquid phase, using oxygen, carbon dioxide, water and dilute aqueous amine solutions. The liquid-solid mass transfer coefficient will also be determined in the bubble as well as the pulse flow regimes using solid benzoic acid particles in the packing and measuring their rate of dissolution. The mass transfer coefficients in microgravity will be compared to those in normal gravity cocurrent flow to determine the mass transfer enhancement and propose new mass transfer correlations for two-phase gas-liquid flows through packed beds in microgravity.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: Strategic Research to Enable NASA's Exploration Missions Conference and Workshop: Presentations, Volume 1; 695-709; NASA/CP-2004-213205/VOL1
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    Transitional Bubble in Periodic Flow Phase Shift (2004)
    In:  CASI
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    Publication Date: 2018-06-06
    Description: One particular characteristic observed in unsteady shear layers is the phase shift relative to the main flow. In attached boundary layers this will have an effect both on the instantaneous skin friction and heat transfer. In separation bubbles the contribution to the drag is dominated by the pressure distribution. However, the most significant effect appears to be the phase shift on the transition process. Unsteady transition behaviour may determine the bursting of the bubble resulting in an un-recoverable full separation. An early analysis of the phase shift was performed by Stokes for the incompressible boundary layer of an oscillating wall and an oscillating main flow. An amplitude overshoot within the shear layer as well as a phase shift were observed that can be attributed to the relatively slow diffusion of viscous stresses compared to the fast change of pressure. Experiments in a low speed facility with the boundary layer of a flat plate were evaluated in respect to phase shift. A pressure distribution similar to that on the suction surface of a turbomachinery aerofoil was superimposed generating a typical transitional separation bubble. A periodically unsteady main flow in the suction type wind tunnel was introduced via a rotating flap downstream of the test section. The experiments covered a range of the three similarity parameters of momentum-loss-thickness Reynolds-number of 92 to 226 and Strouhal-number (reduced frequency) of 0.0001 to 0.0004 at the separation point, and an amplitude range up to 19 %. The free stream turbulence level was less than 1% .Upstream of the separation point the phase shift in the laminar boundary layer does not appear to be affected significantly bay either of the three parameters. The trend perpendicular to the wall is similar to the Stokes analysis. The problem scales well with the wave velocity introduced by Stokes, however, the lag of the main flow near the wall is less than indicated analytically. The separation point comes closest to the Stokes analysis but the phase is still 20 degrees lower at the wall.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: Minnowbrook IV: 2003 Workshop on Transition and Unsteady Aspects of Turbomachinery Flows; 54-55; NASA/TM-2004-212913
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    Current Issues in Unsteady Turbomachinery Flows (Images) (2004)
    In:  CASI
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    Publication Date: 2018-06-06
    Description: Among the numerous causes for unsteadiness in turbo machinery flows are turbulence and flow environment, wakes from stationary and rotating vanes, boundary layer separation, boundary layer/shear layer instabilities, presence of shock waves and deliberate unsteadiness for flow control purposes. These unsteady phenomena may lead to flow-structure interactions such as flutter and forced vibration as well as system instabilities such as stall and surge. A major issue of unsteadiness relates to the fact that a fundamental understanding of unsteady flow physics is lacking and requires continued attention. Accurate simulations and sufficient high fidelity experimental data are not available. The Glenn Research Center plan for Engine Component Flow Physics Modeling is part of the NASA 21st Century Aircraft Program. The main components of the plan include Low Pressure Turbine National Combustor Code. The goals, technical output and benefits/impacts of each element are described in the presentation. The specific areas selected for discussion in this presentation are blade wake interactions, flow control, and combustor exit turbulence and modeling.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: Minnowbrook IV: 2003 Workshop on Transition and Unsteady Aspects of Turbomachinery Flows; 3-27; NASA/TM-2004-212913
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    Effects of Elevated Free-Stream Turbulence on Active Control of a Separation Bubble (2004)
    In:  CASI
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    Publication Date: 2018-06-06
    Description: The Effects of elevated free-stream turbulence (FST) on the natural and periodically excited separation bubbles were studied experimentally, due to the relevance of this flow to low-pressure turbine blades at low Reynolds numbers. A bubble was formed at the leading edge of a flat plate and the FST level was altered by placing a grid across the flow at different locations upstream of the plate. The mixing across the separated shear-layer, forming the free boundary of the bubble, increased due to the elevated FST and due to nominally two-dimensional periodic excitation, both flattening and shortening the bubble. Periodic excitation at frequencies that were at least an order of magnitude lower than those associated with the initial shear-layer instability, were very effective at low FST, because the amplitudes of the excitation frequency and its harmonic were amplified over the bubble. High frequency excitation (F+ 3, based on the length of the baseline low FST bubble) had a major effect close to the separation location, while farther downstream the excited fluctuations rapidly decayed in the reattachment region. Low frequency excitation, that generated waves comparable to the length of the unperturbed bubble (F+ 1) were less effective and their magnitude decayed at a slower rate downstream of reattachment. An increase in the level of the FST reduced the net effect of the periodic excitation on the mixing enhancement and subsequent reattachment process, probably due to a destructive interference between the nominally 2D excitation and the random (in space and time) FST, reducing the spanwise coherence and therefore the effectiveness of the current control strategy. However, even at the reduced effectiveness of 2D periodic excitation at elevated FST, it accelerated the reattachment process and the recovery rate of the reattached boundary layer, enhancing the boundary layer resistance to repeat separation and reducing its momentum loss further downstream.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: Minnowbrook IV: 2003 Workshop on Transition and Unsteady Aspects of Turbomachinery Flows; 392-406; NASA/TM-2004-212913/SUPPL
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    Direct Numerical Simulation of Turbulent Condensation in Clouds (2004)
    In:  CASI
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    Publication Date: 2018-06-05
    Description: In this brief, we investigate the turbulent condensation of a population of droplets by means of a direct numerical simulation. To that end, a coupled Navier-Stokes/Lagrangian solver is used where each particle is tracked and its growth by water vapor condensation is monitored exactly. The main goals of the study are to find out whether turbulence broadens the droplet size distribution, as observed in in situ measurements. The second issue is to understand if and for how long a correlation between the droplet radius and the local supersaturation exists for the purpose of modeling sub-grid scale microphysics in cloud-resolving codes. This brief is organized as follows. In Section 2 the governing equations are presented, including the droplet condensation model. The implementation of the forcing procedure is described in Section 3. The simulation results are presented in Section 4 together with a sketch of a simple stochastic model for turbulent condensation. Conclusions and the main outcomes of the study are given in Section 5.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: Annual Research Briefs, 2004: Center for Turbulence Research; 305-316
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    Flow-Tagging Velocimetry for Hypersonic Flows Using Fluorescence of Nitric Oxide (2003)
    In:  CASI
    Details
    Publication Date: 2018-06-02
    Description: We demonstrate a new variation of molecular-tagging velocimetry for hypersonic flows based on laser-induced fluorescence. A thin line of nitric-oxide molecules is excited with a laser beam and then, after a time delay, a fluorescence image of the displaced line is acquired. One component of velocity is determined from the time of flight. This method is applied to measure the velocity profile in a Mach 8.5 laminar, hypersonic boundary layer in the Australian National University s T2 free-piston shock tunnel. The single-shot velocity measurement uncertainty in the freestream was found to be 3.5%, based on 90% confidence. The method is also demonstrated in the separated flow region forward of a blunt fin attached to a flat plate in a Mach 7.4 flow produced by the Australian National University s T3 free-piston shock tunnel. The measurement uncertainty in the blunt fin experiment is approximately 30%, owing mainly to low fluorescence intensities, which could be improved significantly in future experiments. This velocimetry method is applicable to very high-speed flows that have low collisional quenching of the fluorescing species. It is particularly convenient in facilities where planar laser-induced fluorescence is already being performed.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: AIAA Journal; Volume 41; No. 2; 263-271
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    A Parametric Study of Jet Interactions with Rarefied Flow (2004)
    In:  CASI
    Details
    Publication Date: 2018-06-02
    Description: Three-dimensional computational techniques, in particular the uncoupled CFD-DSMC of the present study, are available to be applied to problems such as jet interactions with variable density regions ranging from a continuum jet to a rarefied free stream. When the value of the jet to free stream momentum flux ratio approximately greater than 2000 for a sharp leading edge flat plate forward separation vortices induced by the jet interaction are present near the surface. Also as the free stream number density n (infinity) decreases, the extent and magnitude of normalized pressure increases and moves upstream of the nozzle exit. Thus for the flat plate model the effect of decreasing n (infinity) is to change the sign of the moment caused by the jet interaction on the flat plate surface.
    Keywords: Fluid Mechanics and Thermodynamics
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    "Smart" Magnetic Fluids Experiment Operated on the International Space Station (2004)
    In:  CASI
    Details
    Publication Date: 2018-06-02
    Description: InSPACE is a microgravity fluid physics experiment that was operated on the International Space Station (ISS) in the Microgravity Science Glovebox from late March 2003 through early July 2003. (InSPACE is an acronym for Investigating the Structure of Paramagnetic Aggregates From Colloidal Emulsions.) The purpose of the experiment is to obtain fundamental data of the complex properties of an exciting class of smart materials termed magnetorheological (MR) fluids. MR fluids are suspensions, or colloids, comprised of small (micrometer-sized) superparamagnetic particles in a nonmagnetic medium. Colloids are suspensions of very small particles suspended in a liquid. (Examples of other colloids are blood, milk, and paint.) These controllable fluids can quickly transition into a nearly solid state when exposed to a magnetic field and return to their original liquid state when the magnetic field is removed. Controlling the strength of the magnetic field can control the relative stiffness of these fluids. MR fluids can be used to improve or develop new seat suspensions, robotics, clutches, airplane landing gear, and vibration damping systems. The principal investigator for InSPACE is Professor Alice P. Gast of the Massachusetts Institute of Technology (MIT). The InSPACE hardware was developed at the NASA Glenn Research Center. The InSPACE samples were delivered to the ISS in November 2002, on the Space Shuttle Endeavour, on Space Station Utilization Flight UF-2/STS113. Operations began on March 31, 2003, with the processing of three different particle size samples at multiple test parameters. This investigation focused on determining the structural organization of MR colloidal aggregates when exposed to a pulsing magnetic field. On Earth, the aggregates take the shape of footballs with spiky tips. This characteristic shape may be influenced by the pull of gravity, which causes most particles initially suspended in the fluid to sediment, (i.e., settle and collect at the bottom of the cell). In the absence of sedimentation effects on the ISS, the behavior and shape of these MR aggregate structures are dominated exclusively by magnetic and surface tension forces. The microscopic detail of these structures was imaged under two orthogonal camera views. The video was downlinked to the InSPACE team at Glenn's Telescience Support Center and to MIT and also recorded onboard the ISS on videotapes that will be brought back to the ground by the space shuttles. The study examined the effect on the structure formation by varying the magnetic field strength and pulse frequency, and particle size. Fundamental data that characterized the structure formation were obtained. InSPACE completed its last planned test run on July 2, 2003. Operations occurred on 21 days over approximately a 3-month period. Forty-one test points were completed during 26 test runs. During the initial testing, the procedures followed by the crew were modified to maximize the observation of some unexpected and interesting aggregate behavior. As a result Dr. Gast has reported on the formation of aggregate shapes that are more extended and diverse than those observed on the ground. Sheets of magnetic material folded over in a labyrinth pattern and large columnar aggregates with complex interfaces with the surrounding fluid are examples of the interesting structures that have been observed on the ISS. In light of these early findings, the understanding of the fundamental properties of MR fluids on the basis of ground-based observations may need to be reconsidered.The experiments on the ISS have provided a vast amount of video data for analysis. While this analysis is ongoing, plans are being made for additional experimental runs. For this purpose, additional hardware and cells containing samples of different magnetic particles and sizes are being fabricated for a future launch to the ISS. The InSPACE hardware will remain on orbit until this testing is completed.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: Research and Technology 2003; NASA/TM-2004-212729
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    Nonlinear Acoustics Used To Reduce Leakage Flow (2004)
    In:  CASI
    Details
    Publication Date: 2018-06-02
    Description: Leakage and wear are two fundamental problems in all traditional turbine seals that contribute to an engine's inefficiency. The solutions to seal leakage and wear conflict in the conventional design space. Reducing the clearance between the seal and rotating shaft reduces leakage but increases wear because of increased contact incidents. Increasing the clearance to reduce the contact between parts reduces wear but increases parasitic leakage. The goal of this effort is to develop a seal that restricts leakage flow using acoustic pressure while operating in a noncontacting manner, thereby increasing life. In 1996, Dr. Timothy Lucas announced his discovery of a method to produce shock-free high-amplitude pressure waves. For the first time, the formation of large acoustic pressures was possible using dissonant resonators. A pre-prototype acoustic seal developed at the NASA Glenn Research Center exploits this fundamental acoustic discovery: a specially shaped cavity oscillated at the contained fluid's resonant frequency produces high-amplitude acoustic pressure waves of a magnitude approaching those required of today's seals. While the original researchers are continuing their development of acoustic pumps, refrigeration compressors, and electronic thermal management systems using this technology, the goal of researchers at Glenn is to apply these acoustic principles to a revolutionary sealing device. When the acoustic resonator shape is optimized for the sealing device, the flow from a high-pressure cavity to a low-pressure cavity will be restricted by a series of high-amplitude standing pressure waves of higher pressure than the pressure to be sealed. Since the sealing resonator cavity will not touch the adjacent sealing structures, seal wear will be eliminated, improving system life. Under a cooperative agreement between Glenn and the Ohio Aerospace Institute (OAI), an acoustic-based pre-prototype seal was demonstrated for the first time. A pressurized cavity was attached to one end of the resonator while the other end remained open to ambient pressure. Measurements were taken at several values of applied pressure with the assembly stationary, oscillated at an off-resonance frequency, and then oscillated on-resonance. The three cases show that the flow through the conical resonator can be reduced by oscillating the resonator at the resonance frequency of the air contained within the cavity. The results are currently being compared with results obtained from a commercial computational fluid dynamics code. The objective is to improve the design through numerical simulation before fabricating a next-generation prototype sealing device. Future work is aimed at implementing acoustic seal design improvements to further reduce the leakage flow rate through the device and at reducing the device's overall size.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: Research and Technology 2003; NASA/TM-2004-212729
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    Contact Angle of Drops Measured on Nontransparent Surfaces and Capillary Flow Visualized (2003)
    In:  CASI
    Details
    Publication Date: 2018-06-02
    Description: The spreading of a liquid on a solid surface is important for various practical processes, and contact-angle measurements provide an elegant method to characterize the interfacial properties of the liquid with the solid substrates. The complex physical processes occurring when a liquid contacts a solid play an important role in determining the performance of chemical processes and materials. Applications for these processes are in printing, coating, gluing, textile dyeing, and adhesives and in the pharmaceutical industry, biomedical research, adhesives, flat panel display manufacturing, surfactant chemistry, and thermal engineering.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: Research and Technology 2002; NASA/TM-2003-211990
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    Two-Fluid Interface Instability Being Studied (2003)
    In:  CASI
    Details
    Publication Date: 2018-06-02
    Description: The interface between two fluids of different density can experience instability when gravity acts normal to the surface. The relatively well known Rayleigh-Taylor (RT) instability results when the gravity is constant with a heavy fluid over a light fluid. An impulsive acceleration applied to the fluids results in the Richtmyer-Meshkov (RM) instability. The RM instability occurs regardless of the relative orientation of the heavy and light fluids. In many systems, the passing of a shock wave through the interface provides the impulsive acceleration. Both the RT and RM instabilities result in mixing at the interface. These instabilities arise in a diverse array of circumstances, including supernovas, oceans, supersonic combustion, and inertial confinement fusion (ICF). The area with the greatest current interest in RT and RM instabilities is ICF, which is an attempt to produce fusion energy for nuclear reactors from BB-sized pellets of deuterium and tritium. In the ICF experiments conducted so far, RM and RT instabilities have prevented the generation of net-positive energy. The $4 billion National Ignition Facility at Lawrence Livermore National Laboratory is being constructed to study these instabilities and to attempt to achieve net-positive yield in an ICF experiment.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: Research and Technology 2002; NASA/TM-2003-211990
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    Thermal Response of Cooled Silicon Nitride Plate Due to Thermal Conductivity Effects Analyzed (2003)
    In:  CASI
    Details
    Publication Date: 2018-06-02
    Description: Lightweight, strong, tough high-temperature materials are required to complement efficiency improvements for next-generation gas turbine engines that can operate with minimum cooling. Because of their low density, high-temperature strength, and high thermal conductivity, ceramics are being investigated as materials to replace the nickelbase superalloys that are currently used for engine hot-section components. Ceramic structures can withstand higher operating temperatures and a harsh combustion environment. In addition, their low densities relative to metals help reduce component mass (ref. 1). To complement the effectiveness of the ceramics and their applicability for turbine engine applications, a parametric study using the finite element method is being carried out. The NASA Glenn Research Center remains very active in conducting and supporting a variety of research activities related to ceramic matrix composites through both experimental and analytical efforts (ref. 1). The objectives of this work are to develop manufacturing technology, develop a thermal and environmental barrier coating (TBC/EBC), develop an analytical modeling capability to predict thermomechanical stresses, and perform a minimal burner rig test on silicon nitride (Si3N4) and SiC/SiC turbine nozzle vanes under simulated engine conditions. Moreover, we intend to generate a detailed database of the material s property characteristics and their effects on structural response. We expect to offer a wide range of data since the modeling will account for other variables, such as cooling channel geometry and spacing. Comprehensive analyses have begun on a plate specimen with Si3N4 cooling holes.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: Research and Technology 2002; NASA/TM-2003-211990
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    Spontaneous Raman Scattering (SRS) System for Calibrating High-Pressure Flames Became Operational (2003)
    In:  CASI
    Details
    Publication Date: 2018-06-02
    Description: A high-performance spontaneous Raman scattering (SRS) system for measuring quantitative species concentration and temperature in high-pressure flames is now operational. The system is located in Glenn s Engine Research Building. Raman scattering is perhaps the only optical diagnostic technique that permits the simultaneous (single-shot) measurement of all major species (N2, O2, CO2, H2O, CO, H2, and CH4) as well as temperature in combustion systems. The preliminary data acquired with this new system in a 20-atm hydrogen-air (H2-air) flame show excellent spectral coverage, good resolution, and a signal-to-noise ratio high enough for the data to serve as a calibration standard. This new SRS diagnostic system is used in conjunction with the newly developed High- Pressure Gaseous Burner facility (ref. 1). The main purpose of this diagnostic system and the High-Pressure Gaseous Burner facility is to acquire and establish a comprehensive Raman-scattering spectral database calibration standard for the combustion diagnostic community. A secondary purpose of the system is to provide actual measurements in standardized flames to validate computational combustion models. The High-Pressure Gaseous Burner facility and its associated SRS system will provide researchers throughout the world with new insights into flame conditions that simulate the environment inside the ultra-high-pressure-ratio combustion chambers of tomorrow s advanced aircraft engines.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: Research and Technology 2002; NASA/TM-2003-211990
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    Postseismic Transient after the 2002 Denali Fault Earthquake from VLBI Measurements at Fairbanks (2004)
    In:  CASI
    Details
    Publication Date: 2018-06-06
    Description: The VLBI antenna (GILCREEK) at Fairbanks, Alaska observes in networks routinely twice a week with operational networks and on additional days with other networks on a more uneven basis. The Fairbanks antenna position is about 150 km north of the Denali fault and from the earthquake epicenter. We examine the transient behavior of the estimated VLBI position during the year following the earthquake to determine how the rate of change of postseismic deformation has changed. This is compared with what is seen in the GPS site position series.
    Keywords: Geophysics
    Type: International VLBI Service for Geodesy and Astrometry 2004 General Meeting Proceedings; 491-495; NASA/CP-2004-212255
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    The Magnetospheric Constellation Mission (MC-DRACO) (2003)
    In:  CASI
    Details
    Publication Date: 2018-12-12
    Description: The Magnetospheric Constellation Mission Dynamic Response and Coupling Observatory (MC-DRACO), the logical outgrowth of a sequence of STP missions, will explore plasma transport and energy conversion processes over a broad range of spatial sizes. Designed to be a meso-/macroscope for the magnetotail, it will resolve persistent controversies and yield a new understanding on which to build a predictive science of next generation magnetospheric meteorology.
    Keywords: Geophysics
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    Implications of the Utopia Gravity Anomaly for the Resurfacing of the Northern Plains of Mars (2004)
    In:  CASI
    Details
    Publication Date: 2017-10-02
    Description: Whereas the surface units of the northern plain of Mars generally exhibit ages ranging from late Hesperian to Amazonian, interpretation of precise topographic measurements indicate that the age of the underlying "basement" is early Noachian, or almost as old as the southern highlands. This suggests that widespread but relatively superficial resurfacing has occurred throughout the northern plains since the end of early heavy bombardment. In this abstract I examine some of the possible implications of the subsurface structure inferred for the Utopia basin from gravity data on the nature of this resurfacing. The large, shallow, circular depression in Utopia Planitia has been identified as a huge impact basin, based on both geological evidence and detailed analysis of MOLA topography. Its diameter (approx. 3000 km) is equivalent to that of the Hellas basin, as is its inferred age (early Noachian). However, whereas Hellas is extremely deep with rough terrain and large slopes, the Utopia basin is a smooth, shallow, almost imperceptible bowl. Conversely, Utopia displays one of the largest (non-Tharsis-related) positive geoid anomalies on Mars, in contrast to a much more subdued negative anomaly over Hellas.
    Keywords: Geophysics
    Type: Second Conference on Early Mars: Geologic, Hydrologic, and Climatic Evolution and the Implications for Life; LPI-Contrib-1211
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    Rationale for Seismic Measurements on Mars by a Single Station (2003)
    In:  CASI
    Details
    Publication Date: 2017-10-02
    Description: We present here some of the scientific objectives which can be achieved by a single seismic station on Mars, equipped with a 3 axis VBB seismometer and a 3 axis Short Period Seismometer. We assume that this station is also equipped with meteorological sensors, including infra-sound and pressure, in order to perform a complete meteorological noise correction. The science objectives are listed in order of increasing difficulty.
    Keywords: Geophysics
    Type: Sixth International Conference on Mars; LPI-Contrib-1164
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    Strangelove Ocean and Deposition of Unusual Shallow-Water Carbonates After the End-Permian Mass Extinction (2003)
    In:  CASI
    Details
    Publication Date: 2017-10-02
    Description: The severe mass extinction of marine and terrestrial organisms at the end of the Permian Period (approx. 251 Ma) was accompanied by a rapid negative excursion of approx. 3 to 4 per mil in the carbon-isotope ratio of the global surface oceans and atmosphere that persisted for some 500,000 into the Early Triassic. Simulations with an ocean-atmosphere/carbon-cycle model suggest that the isotope excursion can be explained by collapse of ocean primary productivity (a Strangelove Ocean) and changes in the delivery and cycling of carbon in the ocean and on land. Model results also suggest that perturbations of the global carbon cycle resulting from the extinctions led to short-term fluctuations in atmospheric pCO2 and ocean carbonate deposition, and to a long-term (〉1 Ma) decrease in sedimentary burial of organic carbon in the Triassic. Deposition of calcium carbonate is a major sink of river-derived ocean alkalinity and for CO2 from the ocean/atmosphere system. The end of the Permian was marked by extinction of most calcium carbonate secreting organisms. Therefore, the reduction of carbonate accumulation made the oceans vulnerable to a build-up of alkalinity and related fluctuations in atmospheric CO2. Our model results suggest that an increase in ocean carbonate-ion concentration should cause increased carbonate accumulation rates in shallow-water settings. After the end-Permian extinctions, early Triassic shallow-water sediments show an abundance of abiogenic and microbial carbonates that removed CaCO3 from the ocean and may have prevented a full 'ocean-alkalinity crisis' from developing.
    Keywords: Geophysics
    Type: Third International Conference on Large Meteorite Impacts; LPI-Contrib-1167
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    Annual Cycles of Multiyear Sea Ice Coverage of the Arctic Ocean: 1999-2003 (2004)
    In:  Other Sources
    Details
    Publication Date: 2018-06-11
    Description: For the years 1999-2003, we estimate the time-varying perennial ice zone (PIZ) coverage and construct the annual cycles of multiyear (MY, including second year) ice coverage of the Arctic Ocean using QuikSCAT backscatter, MY fractions from RADARSAT, and the record of ice export from satellite passive microwave observations. An area balance approach extends the winter MY coverage from QuikSCAT to the remainder of the year. From these estimates, the coverage of MY ice at the beginning of each year is 3774 x 10(exp 3) sq km (2000), 3896 x 10(exp 3) sq km (2001), 4475 x 10(exp 3) sq km (2002), and 4122 x 10(exp 3) sq km (2003). Uncertainties in coverage are approx.150 x 10(exp 3) sq km. In the mean, on 1 January, MY ice covers approx.60% of the Arctic Ocean. Ice export reduces this coverage to approx.55% by 1 May. From the multiple annual cycles, the area of first-year (FY) ice that survives the intervening summers are 1192 x 10(exp 3) sq km (2000), 1509 x 10(exp 3) sq km (2001), and 582 x 10(exp 3) sq km (2002). In order for the MY coverage to remain constant from year to year, these replenishment areas must balance the overall area export and melt during the summer. The effect of the record minimum in Arctic sea ice area during the summer of 2002 is seen in the lowest area of surviving FY ice of the three summers. In addition to the spatial coverage, the location of the PIZ is important. One consequence of the unusual location of the PIZ at the end of the summer of 2002 is the preconditioning for enhanced export of MY ice into the Barents and Kara seas. Differences between the minimums in summer sea ice coverage from our estimates and passive microwave observations are discussed.
    Keywords: Geophysics
    Type: Journal of Geophysical Research; Volume 109
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    The Condensation Line of Air and the Heats of Vaporization of Oxygen and Nitrogen (1953)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The condensation pressure of air was determined over the range of temperature from 60 to 85 K. The experimental results were slightly higher than the calculated values based on the ideal solution law. Heat of vaporization of oxygen was determined at four temperatures ranging from about 68 to 91 K and of nitrogen similarly at four temperatures ranging from 62 to 78 K.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: NACA-TN-2969
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    An Analytical Study of Heat Requirements for Icing Protection of Radomes (1953)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The heat requirements for the icing protection of two radome configurations have been studied over a range of design icing conditions. Both the protection limits of a typical thermal protection system and the relative effects of the various icing variables have been determined. For full evaporation of all impinging water, an effective heat density of 14 watts per square inch was required. When a combination of the evaporation and running wet surface systems was employed, a heat requirement of 5 watts per square inch provided protection at severe icing and operating conditions.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: NACA-RM-E53A22
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    Variability in the atmosphere-ocean system and global change: insights via sea surface temperature analysis (2003)
    In:  Other Sources
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    Publication Date: 2018-06-08
    Keywords: Geophysics
    Type: American Geophysical Union Fall Meeting; San Francisco, CA; United States
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    Anisotrophy of water cloud reflectance: A comparison of measurements and ID theory (2004)
    In:  Other Sources
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    Publication Date: 2018-06-08
    Description: Bi-directional reflectances of marine liquid water clouds, as measured by the Multiangle Imaging SpectroRadiometer (MISR), are compared with plane-parallel radiative transfer model calculations.
    Keywords: Geophysics
    Type: Geophysical Research Letters; Volume 30; no. 1
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    Validation of a global ionospheric data assimilation model (2003)
    In:  Other Sources
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    Publication Date: 2018-06-08
    Keywords: Geophysics
    Type: 2003 International Union of Geodesy and Geophysics (IUGG) General Assembly; Sapporo; Japan
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    The IAG/IAPSO Joint Working Group on geodetic effects of nontidal oceanic processes (2003)
    In:  Other Sources
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    Publication Date: 2018-06-08
    Keywords: Geophysics
    Type: XXIII General Assembly of the International Union of Geodesy and Geophysics; Sapporo; Japan
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    Space weather: geomagnetic quiet, HILDCAAs, magnetic storms and extreme storms (2003)
    In:  Other Sources
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    Publication Date: 2018-06-08
    Keywords: Geophysics
    Type: Space Weather: Geomagnetic Quiet, HILDCAAs, Magnetic Storms and Extreme Storms; San Diego, CA; United States
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    New empirically-derived solar radiation pressure model for GPS satellites (2003)
    In:  Other Sources
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    Publication Date: 2018-06-08
    Keywords: Geophysics
    Type: European Geophysical Society; Nice; France
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    Energy dissipation rate inferred from spectra of long internal gravity waves (2003)
    In:  Other Sources
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    Publication Date: 2018-06-08
    Keywords: Geophysics
    Type: XXII General Assembly of the International Union of Geodesy and Geophysics; Sapporo; Japan
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    Atmospheric and oceanic excitation of length-of-day variations during 1980-2000 (2003)
    In:  Other Sources
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    Publication Date: 2018-06-08
    Keywords: Geophysics
    Type: EGS-AGU-EUG Joint Assembly; Nice; France
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    Role of the Indian Ocean salinity in monsoon and ENSO variability as simulated by a coupled ocean-atmosphere system (2003)
    In:  Other Sources
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    Publication Date: 2018-06-08
    Keywords: Geophysics
    Type: International Union of Geodesy and Geophysics (IUGG): New Perspectives of Coupled Tropical Ocean-Atmosphere Dynamics and Predictability; Sapporo; Japan
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    On the physical consistency of data assimilation and a computationally effective approximate smoother (2003)
    In:  Other Sources
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    Publication Date: 2018-06-08
    Keywords: Geophysics
    Type: International Union of Geodesy and Geophysics (IUGG) 2003 Conference; Sapporo; Japan
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    A new DSD algorithm for the dual-frequency wind profiler (2003)
    In:  Other Sources
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    Publication Date: 2018-06-08
    Keywords: Geophysics
    Type: International Union of Geodesy and Geophysics IUGG 2003 General Assembly; Sapporo; Japan
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    CDDIS 2001 Global Data Center Report (2004)
    In:  CASI
    Details
    Publication Date: 2018-06-08
    Description: The Crustal Dynamics Data Information System (CDDIS) has supported the International GPS Service (IGS) as a global data center since 1992. The CDDIS activities within the IGS during 2001 are summarized below; this report also includes any changes or enhancements made to the CDDIS during the past year. General CDDIS background and system information can be found in the CDDIS data center summary included in the IGS 1994 Annual Report (Noll, 1995) as well as the subsequent updates (Noll, 1996, Noll, 1997, Noll, 1998, Noll, 1999, and Noll, 2001).
    Keywords: Geophysics
    Type: International GPS Service 2001 - 2002 Technical Reports; 295-304; JPL-Publ-04-017
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    Laser ranging contributions to monitoring and interpreting Earth orientation changes (2003)
    In:  Other Sources
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    Publication Date: 2018-06-08
    Keywords: Geophysics
    Type: IEEE Aerospace Conference; Big Sky, MT; United States
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