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  • Other Sources  (550,074)
  • NASA Technical Reports  (550,074)
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  • Other Sources  (550,074)
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  • 1
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    Advanced Air Vehicles Program: Advancing Research in Hypersonic Flight (2020)
    In:  CASI
    Details
    Publication Date: 2020-01-24
    Description: Presentation on Advancing Research in Hypersonic Flight at "Emerging Hypersonics Market" Panel at Transportation Research Board
    Keywords: Aeronautics (General)
    Type: HQ-E-DAA-TN76966 , Transportation Research Board; Jan 13, 2020; Washington, D.C.; United States
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  • 2
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    Multigrid Preconditioning for a Space-Time Spectral-Element Discontinuous-Galerkin Solver (2020)
    In:  CASI
    Details
    Publication Date: 2020-01-24
    Description: In this work we examine a multigrid preconditioning approach in the context of a high- order tensor-product discontinuous-Galerkin spectral-element solver. We couple multigrid ideas together with memory lean and efficient tensor-product preconditioned matrix-free smoothers. Block ILU(0)-preconditioned GMRES smoothers are employed on the coarsest spaces. The performance is evaluated on nonlinear problems arising from unsteady scale- resolving solutions of the Navier-Stokes equations: separated low-Mach unsteady ow over an airfoil from laminar to turbulent ow. A reduction in the number of ne space iterations is observed, which proves the efficiency of the approach in terms of preconditioning the linear systems, however this gain was not reflected in the CPU time. Finally, the preconditioner is successfully applied to problems characterized by stiff source terms such as the set of RANS equations, where the simple tensor product preconditioner fails. Theoretical justification about the findings is reported and future work is outlined.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: ARC-E-DAA-TN76312 , AIAA SciTech 2020; Jan 06, 2020 - Jan 10, 2020; Orlando, FL; United States
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  • 3
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    Estimation of the Tropical Cyclone Diurnal Cycle Using Simulated Observations from the NASA TROPICS Earth Venture Mission (2020)
    In:  CASI
    Details
    Publication Date: 2020-01-24
    Description: No abstract available
    Keywords: Meteorology and Climatology
    Type: MSFC-E-DAA-TN76613 , American Meteorological Society (AMS) Annual Meeting; Jan 12, 2020 - Jan 16, 2020; Boston, MA; United States
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  • 4
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    NASA GIBS and Worldview: Leveraging FOSS for NASA Earth Science Data Visualizations (2019)
    In:  Other Sources
    Details
    Publication Date: 2020-01-24
    Description: The NASA Global Imagery Browse Services (GIBS) and Worldview interactive mapping site leverage scientific and community best practices, open source software, and public standards to provide a scalable, compliant, and authoritative source for NASA Earth Observing System (EOS) Earth science data visualizations. GIBS and Worldview allow end users to easily and quickly interact with more than 800 full resolution pre-generated raster- and vector-based visualizations. This interactive discovery approach relies on visual observation and identification of phenomena that are not as simply identified otherwise. This eLightning presentation will exhibit the broad set of capabilities and visualization layers made possible through the GIBS and Worldview open source software. Specific dependencies on, and contributions to, open source software will be highlighted. Additionally, opportunities for future improvements for better interoperability and reuse through open source software will be discussed.
    Keywords: Earth Resources and Remote Sensing
    Type: GSFC-E-DAA-TN76098 , American Geophysical Union (AGU) Fall Meeting 2019; Dec 09, 2019 - Dec 13, 2019; San Francisco, CA; United States
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  • 5
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    Multiple Shaker Placement for Ground Vibration Test of X-59 Aircraft Using Topology Optimization (2020)
    In:  CASI
    Details
    Publication Date: 2020-01-24
    Description: A multiple shaker placement methodology is developed and tested using a topology optimization technique. Current multiple shaker placement methodology requires optimum accelerometer placement and optimum single-shaker placement techniques. The proposed methodology is tested using a finite element model of the X-59 Low Boom Flight Demonstrator aircraft. The effective independence and the driving point acceleration transfer function (DPATF) methods are used for the accelerometer placement study. In this study, four shakers are used to excite each mode more effectively during the ground vibration test; all the modes of interest thus are separated into four groups. Each shaker takes care of a separate group of modes. Grouping the modes of interest is performed utilizing topology optimization. The number of modes for each group therefore will be automatically decided during grouping. For each group of modes, perform the following two steps to determine optimal location of four shakers: 1) At each accelerometer location, compare the magnitude of DPATF values at natural frequencies, select the minimum value, and make a vector with these minimum values of the DPATF magnitudes for each group; and 2) Select the degrees of freedom corresponding to the maximum value of this vector. The objective function value is the maximum value of the vector with minimum value of the magnitude of the superposed acceleration transfer function. This objective function value is maximized by changing the modes for each group. Forty accelerometers are enough to have good correlation between mode shapes obtained from the reduced order model and the simulated ground vibration test.
    Keywords: Numerical Analysis; Aircraft Design, Testing and Performance
    Type: AFRC-E-DAA-TN73257 , SciTech 2020; Jan 06, 2020 - Jan 10, 2020; Orlando, FL; United States
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  • 6
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    AJAX CABOTS Data (2020)
    In:  CASI
    Details
    Publication Date: 2020-01-24
    Description: The Alpha Jet Atmospheric eXperiment (AJAX) airborne science project based out of NASA Ames Research Center performed eight science flights in coordination with the California Baseline Ozone Transport Study (CABOTS) campaign. Many of these flights included a series of vertical profiles (~ 0-5 km) distributed roughly along either a North/South or East/West transect. Some flights also connected the fixed-location measurements at Visalia (TOPAZ ozone lidar) and Bodega Bay (ozonesondes). AJAX measured ozone, carbon dioxide, methane, water vapor, and 3-D winds on each flight, and those in situ measurements are the basis of the data sets collected here. Trace gas data sets including time and aircraft position have been delivered as comma-separated-value text files. Meteorological data (temperature, pressure and 3-dimensional winds) are provided at 1 Hz in ICARTT-compliant text files.
    Keywords: Earth Resources and Remote Sensing
    Type: ARC-E-DAA-TN77025
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  • 7
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    Pattern-Based Genetic Algorithm for Airborne Conflict Resolution (2006)
    In:  CASI
    Details
    Publication Date: 2020-01-24
    Description: NASA has developed the Autonomous Operations Planner (AOP) airborne decision support tool to explore advanced air traffic control concepts that include delegating separation authority to aircraft. A key element of the AOP is its strategic conflict resolution (CR) algorithm, which must resolve conflicts while maintaining conformance with traffic flow management constraints. While a previous CR algorithm, which focused on broader flight plan optimization objectives as a part of conflict resolution, had successfully been developed, new research has identified the need for resolution routes the users find more acceptable (i.e., simpler and more intuitive). A new CR algorithm is presented that uses a combination of pattern-based maneuvers and a genetic algorithm to achieve these new objectives. Several lateral and vertical maneuver patterns are defined and the application of the genetic algorithm explained. A new approach to defining a conflicted fitness function using estimates of the local conflict region around a conflicted trajectory is also presented. Preliminary performance characteristics of the implemented algorithm are provided.
    Keywords: Air Transportation and Safety
    Type: NF1676L-LARC , AIAA Guidance, Navigation, and Control Conference and Exhibit; Aug 21, 2006 - Aug 24, 2006; Keystone, CO; United States
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  • 8
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    Enabling Entry Technologies for Ice Giant Missions (2020)
    In:  CASI
    Details
    Publication Date: 2020-01-24
    Description: The proposed poster will highlight two NASA developed entry technologies that are enablers for Ice Giant Missions. They are: (1) Heat-shield for Extreme Entry Environment Technology (HEEET), and (2) Adaptable, Deployable, Entry, and Placement Technology (ADEPT), a mechanically deployable entry system. HEEET development is complete and is at TRL 6. HEEET is ready for Ice Giant in situ probe missions, and HEEET is an enabler for either direct ballistic entry or entry from Orbit. NASA plans to sustain the HEEET capability as it is needed for Venus, Saturn and higher speed sample return missions in addition to Ice Giant Missions. The emerging recognition among the scientific community that by delivering the probe from orbit will allow for simultaneous in-situ and orbital measurement can be enabled by aerocapture using ADEPT. The drag modulated aerocapture (DMA) with ADEPT is the simplest approach that can deliver an orbiter and probe together and without the significant penalty associated with propulsive insertion. Studies performed by JPL and NASA Ames teams point to this very promising possibility. Numerous DMA with ADEPT studies point to its applicability to small spacecraft missions as well as Ice Giant missions. The poster will present the current state of readiness of HEEET, ADEPT and DMA.
    Keywords: Lunar and Planetary Science and Exploration
    Type: ARC-E-DAA-TN76382 , Ice Giants Systems; Jan 20, 2020 - Jan 22, 2020; London, England; United Kingdom
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  • 9
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    Rapid Expansion of Northern Peatlands and Doubled Estimate of Carbon Storage (2019)
    In:  Other Sources
    Details
    Publication Date: 2020-01-24
    Description: Northern peatlands are an integral part of the global carbon cyclea strong sink of atmospheric carbon dioxide and source of methane. Increasing anthropogenic carbon dioxide and methane in the atmosphere are thought to strongly impact these environments, and yet, peatlands are not routinely included in Earth system models. Here we present a quantification of the sink and stock of northern peat carbon from the last glacial period through the pre-industrial period. Additional data and new algorithms for reconstructing the history of peat carbon accumulation and the timing of peatland initiation increased the estimate of total northern peat carbon stocks from 545 Gt to 1,055 Gt of carbon. Further, the post-glacial increases in peatland initiation rate and carbon accumulation rate are more abrupt than previously reported. Peatlands have been a strong carbon sink throughout the Holocene, but the atmospheric partial pressure of carbon dioxide has been relatively stable over this period. While processes such as permafrost thaw and coral reef development probably contributed some additional carbon to the atmosphere, we suggest that deep ocean upwelling was the most important mechanism for balancing the peatland sink and maintaining the observed stability.
    Keywords: Earth Resources and Remote Sensing
    Type: GSFC-E-DAA-TN74633 , Nature Geoscience (ISSN 1752-0894) (e-ISSN 1752-0908); 12; 11; 917–921
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  • 10
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    River Flood Prediction Using a Long Short-Term Memory Recurrent Neural Network (2020)
    In:  CASI
    Details
    Publication Date: 2020-01-24
    Description: No abstract available
    Keywords: Meteorology and Climatology
    Type: MSFC-E-DAA-TN76760 , AMS Annual Meeting; Jan 12, 2020 - Jan 16, 2020; Boston, MA; United States
    Format: application/pdf
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