Recursos de colección

NASA Technical Reports Server (NTRS) (686.496 recursos)

The NTRS is a valuable resource for students, educators, researchers, and the public for access to NASA's current and historical technical literature since it was first released in 1994. NTRS provides access to approximately 500K aerospace related citations, 90K full-text online documents, and 111K images and videos. NTRS numbers continues to grow over time as new scientific and technical information (STI) is created or funded by NASA. The type of information found in NTRS include: conference papers, images, journal articles, photos, meeting papers, movies, patents, research reports, and technical videos.

Mostrando recursos 81 - 100 de 321.855

  1. Free-Space Quantum Key Distribution with a High Generation Rate KTP Waveguide Photon-Pair Source

    Battle, P.; Helmick, S.; Lind, A.; Chaffee, D.; Tokars, R.; Pouch, J.; Wilson, N.; Lekki, J.; Roberts, T.; Floyd, B.; Wilson, J.; Cavin, J.
    NASA awarded Small Business Innovative Research (SBIR) contracts to AdvR, Inc to develop a high generation rate source of entangled photons that could be used to explore quantum key distribution (QKD) protocols. The final product, a photon pair source using a dual-element periodically- poled potassium titanyl phosphate (KTP) waveguide, was delivered to NASA Glenn Research Center in June of 2015. This paper describes the source, its characterization, and its performance in a B92 (Bennett, 1992) protocol QKD experiment.

  2. Digital Device Architecture and the Safe Use of Flash Devices in Munitions

    Katz, Richard B.; Bergevin, Keith; Flowers, David
    Flash technology is being utilized in fuzed munition applications and, based on the development of digital logic devices in the commercial world, usage of flash technology will increase. Digital devices of interest to designers include flash-based microcontrollers and field programmable gate arrays (FPGAs). Almost a decade ago, a study was undertaken to determine if flash-based microcontrollers could be safely used in fuzes and, if so, how should such devices be applied. The results were documented in the Technical Manual for the Use of Logic Devices in Safety Features. This paper will first review the Technical Manual and discuss the rationale...

  3. Environmental Effects on Data Retention in Flash Cells

    Flowers, David; Katz, Rich; Bergevin, Keith
    Flash technology is being utilized in fuzed munition applications and, based on the development of digital logic devices in the commercial world, usage of flash technology will increase. Antifuse technology, prevalent in non-volatile field programmable gate arrays (FPGAs), will eventually be phased out as new devices have not been developed for approximately a decade. The reliance on flash technology presents a long-term reliability issue for both DoD and NASA safety- and mission-critical applications. A thorough understanding of the data retention failure modes and statistics associated with Flash data retention is of vital concern to the fuze safety community. A key...

  4. Lessons from the James Webb Space Telescope Vibration Test Prep

    Schwartz, T.
    Vibration testing of James Webb Space Telescope OTIS on the new vibration facility at Goddard Space Flight Center.

  5. Urban Biomining Meets Printable Electronics: End-To-End at Destination Biological Recycling and Reprinting

    Navarrete, Jesica; Koehne, Jessica; Gandhiraman, Ram; Rothschild, Lynn J.; Spangle, Dylan
    Space missions rely utterly on metallic components, from the spacecraft to electronics. Yet, metals add mass, and electronics have the additional problem of a limited lifespan. Thus, current mission architectures must compensate for replacement. In space, spent electronics are discarded; on earth, there is some recycling but current processes are toxic and environmentally hazardous. Imagine instead an end-to-end recycling of spent electronics at low mass, low cost, room temperature, and in a non-toxic manner. Here, we propose a solution that will not only enhance mission success by decreasing upmass and providing a fresh supply of electronics, but in addition has...

  6. Microbial Standards of Commercially Available Produce

    Scotten, Jessica
    Limits and guidelines are set on microbial counts in produce to protect the consumer. Different agencies make specifications, which constitute when a product becomes unsafe for human consumption. Producers design their procedures to comply with the limits, but they are responsible creating their own internal standards. The limits and guidelines are summarized here to be applied to assess the microbial safety of the NASA Veggie Program.

  7. The Scintillation Prediction Observations Research Task (SPORT) Mission Overview

    Krause, Linda; Fry, G.; Bishop, Rebecca; Casas, Joseph; Heelis, Rod; Loures, Luis; Swenson, Charles; Durao, Otavio; Nash-Stevenson, Shelia; Spann, James; Le, Guan; Abdu, Mangalathayli
    No abstract available

  8. Temporal Evolution and Mapping of Intense Convective Systems Using TROPICS

    Cecil, Daniel J.
    No abstract available

  9. Airborne Hyperspectral Imaging Studies of Harmful Algal Blooms

    Tokars, Roger; Anderson, Robert; Shuchman, Robert; Leshkevich, George; Demers, James; Flatico, Joseph M.; Czajkowski, Kevin; Becker, Ricky; Ortiz, Joseph; Lekki, John; Kojima, Jun; Liou, Larry; Nguyen, Quang-Viet; Brooks, Colin
    Algae monitoring of the great lakes by NASA GRC researchers.

  10. Performance and Durability of Environmental Barrier Coatings on SiC/SiC Ceramic Matrix Composites

    Zhu, Dongming; Bhatt, Ramakrishna; Harder, Bryan
    This presentation highlights advanced environmental barrier coating (EBC) and SiC-SiC Ceramic Matrix Composites (CMC) systems for next generation turbine engines. The emphasis will be placed on fundamental coating and CMC property evaluations; and the integrated system performance and degradation mechanisms in simulated laboratory turbine engine testing environments. Long term durability tests in laser rig simulated high heat flux the rmomechanical creep and fatigue loading conditions will also be presented. The results can help improve the future EBC-CMC system designs, validating the advanced EBC-CMC technologies for hot section turbine engine applications.

  11. Beyond 3-D: The New Spectrum of Lidar Applications for Earth and Ecological Sciences

    LeWinter, Adam L.; Muller, Jorg; Magney, Troy S.; Morton, Douglas C.; Glennie, Craig L.; Eitel, Jan U. H.; Hofle, Bernhard; Vierling, Lee A.; Abellan, Antonio; Mandlburger, Gottfried; Vierling, Kerri; Deems, Jeffrey S.; Asner, Gregory P.; Joerg, Phillip C.
    Capturing and quantifying the world in three dimensions (x,y,z) using light detection and ranging (lidar) technology drives fundamental advances in the Earth and Ecological Sciences (EES). However, additional lidar dimensions offer the possibility to transcend basic 3-D mapping capabilities, including i) the physical time (t) dimension from repeat lidar acquisition and ii) laser return intensity (LRI) data dimension based on the brightness of single- or multi-wavelength () laser returns. The additional dimensions thus add to the x,y, and z dimensions to constitute the five dimensions of lidar (x,y,z, t, LRI1... n). This broader spectrum of lidar dimensionality has already revealed...

  12. Revisiting Short-Wave-Infrared (SWIR) Bands for Atmospheric Correction in Coastal Waters

    Roger, Jean-Claude; Ahmad, Ziauddin; Pahlevan, Nima
    The shortwave infrared (SWIR) bands on the existing Earth Observing missions like MODIS have been designed to meet land and atmospheric science requirements. The future geostationary and polar-orbiting ocean color missions, however, require highly sensitive SWIR bands (greater than 1550nm) to allow for a precise removal of aerosol contributions. This will allow for reasonable retrievals of the remote sensing reflectance (R(sub rs)) using standard NASA atmospheric corrections over turbid coastal waters. Design, fabrication, and maintaining high-performance SWIR bands at very low signal levels bear significant costs on dedicated ocean color missions. This study aims at providing a full analysis of...

  13. Synoptic Scale Influences on Increasing Summertime Extreme Precipitation Events in the Northeastern United States

    Bosilovich, Mike; Koster, Randal; Collow, Allison
    Over the past 15 years, the northeastern United States has seen a statistically significant increase in the frequency of extreme precipitation events that is larger and more widespread than anywhere else in the country. This increase in events is more likely to be associated with frontal and low-pressure systems, rather than being caused by more tropical cyclones impacting the region.

  14. University-Level Teaching of Anthropogenic Global Climate Change (AGCC) via Student Inquiry

    Bush, Drew; Seiler, Gale; Chandler, Mark; Sieber, Renee
    This paper reviews university-level efforts to improve understanding of anthropogenic global climate change (AGCC) through curricula that enable student scientific inquiry. We examined 152 refereed publications and proceedings from academic conferences and selected 26 cases of inquiry learning that overcome specific challenges to AGCC teaching. This review identifies both the strengths and weaknesses of each of these case studies. It is the first to go beyond examining the impact of specific inquiry instructional approaches to offer a synthesis of cases. We find that inquiry teaching can succeed by concretising scientific processes, providing access to global data and evidence, imparting critical...

  15. A Quasi-Global Approach to Improve Day-Time Satellite Surface Soil Moisture Anomalies through the Land Surface Temperature Input

    Lei, Fangni; Parinussa, Robert M.; Holmes, Thomas R. H.; van Der Schalie, Robin; de Jeu, Richard A. M.; Crow, Wade T.
    Passive microwave observations from various spaceborne sensors have been linked to the soil moisture of the Earth's surface layer. A new generation of passive microwave sensors are dedicated to retrieving this variable and make observations in the single theoretically optimal L-band frequency (1-2 GHz). Previous generations of passive microwave sensors made observations in a range of higher frequencies, allowing for simultaneous estimation of additional variables required for solving the radiative transfer equation. One of these additional variables is land surface temperature, which plays a unique role in the radiative transfer equation and has an influence on the final quality of...

  16. Resource Prospector Instrumentation for Lunar Volatiles Prospecting, Sample Acquisition and Processing

    Zacny, K.; Captain, J.; Elphic, R.; Smith, J.; Paz, A.; Colaprete, A.
    Data gathered from lunar missions within the last two decades have significantly enhanced our understanding of the volatile resources available on the lunar surface, specifically focusing on the polar regions. Several orbiting missions such as Clementine and Lunar Prospector have suggested the presence of volatile ices and enhanced hydrogen concentrations in the permanently shadowed regions of the moon. The Lunar Crater Observation and Sensing Satellite (LCROSS) mission was the first to provide direct measurement of water ice in a permanently shadowed region. These missions with other orbiting assets have laid the groundwork for the next step in the exploration of...

  17. The Use of D-Criteria to Assess Meteor Shower Significance

    Moorehead, Althea V.
    In theory, a meteor shower can be distinguished from the sporadic meteor background by its short duration and orbital similarity. In practice, the duration and strength of a shower and the orbital similarity between its constituent meteors varies widely between showers. Further complicating matters is the anisotropy of the sporadic background. These combined factors make it difficult to distinguish between shower and sporadic meteors with a single, static set of criteria. The orbital similarity, or D-, parameters are often used to assess the relationship between meteors [1,2,3]. The more dissimilar two orbits are, the higher their computed D value will...

  18. Spaceport Command and Control System Automation Testing

    Hwang, Andrew
    The Spaceport Command and Control System (SCCS) is the National Aeronautics and Space Administrations (NASA) launch control system for the Orion capsule and Space Launch System, the next generation manned rocket currently in development. This large system requires high quality testing that will properly measure the capabilities of the system. Automating the test procedures would save the project time and money. Therefore, the Electrical Engineering Division at Kennedy Space Center (KSC) has recruited interns for the past two years to work alongside full-time engineers to develop these automated tests, as well as innovate upon the current automation process.

  19. Spaceport Command and Control System Software Development

    Mahlin, Jonathan Nicholas
    There is an immense challenge in organizing personnel across a large agency such as NASA, or even over a subset of that, like a center's Engineering directorate. Workforce inefficiencies and challenges are bound to grow over time without oversight and management. It is also not always possible to hire new employees to fill workforce gaps, therefore available resources must be utilized more efficiently. The goal of this internship was to develop software that improves organizational efficiency by aiding managers, making employee information viewable and editable in an intuitive manner. This semester I created an application for managers that aids in...

  20. Structure and Evolution of the Lunar Interior

    Kamata, S.; Ishihara, Y.; Andrews-Hanna, J. C.; Warren, P.; Keane, J.; Matsuyama, I.; Siegler, M.; Weber, R. C.; Kiefer, W. S.
    Early in its evolution, the Moon underwent a magma ocean phase leading to its differentiation into a feldspathic crust, cumulate mantle, and iron core. However, far from the simplest view of a uniform plagioclase flotation crust, the present-day crust of the Moon varies greatly in thickness, composition, and physical properties. Recent significant improvements in both data and analysis techniques have yielded fundamental advances in our understanding of the structure and evolution of the lunar interior. The structure of the crust is revealed by gravity, topography, magnetics, seismic, radar, electromagnetic, and VNIR remote sensing data. The mantle structure of the Moon...

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