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NASA Technical Reports Server (NTRS) (672,480 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.

NASA Center for AeroSpace Information (CASI) (513,494) NIX Images (81,938)


Mostrando recursos 1 - 20 de 306,476

1. The GEWEX Process Evaluation Study: GEWEX-PROES - Stephens, Graeme; Tselioudis, George; Jakob, Christian
Progress in realistically simulating the energy and water cycles in weather and climate models has been slower than desirable. Climate models submitted to the Coupled Model Intercomparison Project Phase-5 (CMIP-5), while more comprehensive than their predecessors, have shown little to no improvement in their biases in simulating key features of the climate system. As a result, uncertainties in global climate and hydrological sensitivities, and in the simulation of regional climate change, have not been reduced significantly. It is time to make use of these opportunities to significantly advance our understanding of key energy and water cycle processes at a wide...

2. Prototype and Metrics for Data Processing Chain Components of IPM - Ly, Vuong
This presentation lays out the evolution of the Intelligent Payload Module (IPM) vision given that the HyspIRI mission has been delayed. It shows that there has been a focus on airborne vehcile and unmanned aerial systems to further develop the IPM functionality. This of course does not preclude use of the IPM for space missions but provides alternate paths to continue the concept of improved onboard processing for low latency users of science data products.

3. Oxidation Protection of Porous Reaction-Bonded Silicon Nitride - Fox, D. S.
Oxidation kinetics of both as-fabricated and coated reaction-bonded silicon nitride (RBSN) were studied at 900 and 1000 C with thermogravimetry. Uncoated RBSN exhibited internal oxidation and parabolic kinetics. An amorphous Si-C-O coating provided the greatest degree of protection to oxygen, with a small linear weight loss observed. Linear weight gains were measured on samples with an amorphous Si-N-C coating. Chemically vapor deposited (CVD) Si3N4 coated RBSN exhibited parabolic kinetics, and the coating cracked severely. A continuous-SiC-fiber-reinforced RBSN composite was also coated with the Si-C-O material, but no substantial oxidation protection was observed.

4. Chemical Composition of Comet C/2007 N3 (Lulin): Another "Atypical" Comet - Sudholt, Emily; Villanueva, Geronimo; Mumma, Michael; Bonev, Boncho P.; Radeva, Yana; Gibb, Erika; DiSanti, Michael
We measured the volatile chemical composition of comet C/2007 N3 (Lulin) on three dates from 2009 January 30 to February 1 using NIRSPEC, the high-resolution ([lambda]/[Delta][lambda] [approximately] 25,000), long-slit echelle spectrograph at Keck 2. We sampled nine primary (parent) volatile species (H2O, C2H6, CH3OH, H2CO, CH4, HCN, C2H2, NH3, CO) and two product species (OH* and NH2). We also report upper limits for HDO and CH3D. C/2007 N3 (Lulin) displayed an unusual composition when compared to other comets. Based on comets measured to date, CH4 and C2H6 exhibited "normal" abundances relative to water, CO and HCN were only moderately depleted,...

5. NDE Software Developed at NASA Glenn Research Center - Roth, Donald J.; Martin, Richard E.; Nichols, Charles; Rauser, Richard W.; Bonacuse, Peter J.
NASA Glenn Research Center has developed several important Nondestructive Evaluation (NDE) related software packages for different projects in the last 10 years. Three of the software packages have been created with commercial-grade user interfaces and are available to United States entities for download on the NASA Technology Transfer and Partnership Office server (https://sr.grc.nasa.gov/). This article provides brief overviews of the software packages.

6. Examination of the Measurement of Absorption Using the Reverberant Room Method for Highly Absorptive Acoustic Foam - Eric Wolfram; Hughes, William O.; Chris Nottoli; McNelis, Anne M.
The absorption coefficient for material specimens are needed to quantify the expected acoustic performance of that material in its actual usage and environment. The ASTM C423-09a standard, "Standard Test Method for Sound Absorption and Sound Absorption Coefficients by the Reverberant Room Method" is often used to measure the absorption coefficient of material test specimens. This method has its basics in the Sabine formula. Although widely used, the interpretation of these measurements are a topic of interest. For example, in certain cases the measured Sabine absorption coefficients are greater than 1.0 for highly absorptive materials. This is often attributed to the...

7. Microencapsulation Technologies for Corrosion Protective Coating Applications - Pearman, Benjamin; Li, Wenyan; Jolley, Scott; Calle, Luz; Buhrow, Jerry; Zhang, Xuejun
Microencapsulation technologies for functional smart Coatings for autonomous corrosion control have been a research area of strong emphasis during the last decade. This work concerns the development of pH sensitive micro-containers (microparticles and microcapsules) for autonomous corrosion control. This paper presents an overview of the state-of-the-art in the field of microencapsulation for corrosion control applications, as well as the technical details of the pH sensitive microcontainer approach, such as selection criteria for corrosion indicators and corrosion inhibitors; the development and optimization of encapsulation methods; function evaluation before and after incorporation of the microcontainers into coatings; and further optimization to improve...

8. Basic Repair Method - Gibson, Tracy L.
No abstract available

9. Evolution of Orion Mission Design for Exploration Mission 1 and 2 - Dawn, Timothy F.; Gutkowski, Jeffrey P.; Jedrey, Richard M.
The evolving mission design and concepts of NASA's next steps have shaped Orion into the spacecraft that it is today. Since the initial inception of Orion, through the Constellation Program, and now in the Exploration Mission frame-work with the Space Launch System (SLS), each mission design concept and program goal have left Orion with a set of capabilities that can be utilized in many different mission types. Exploration Missions 1 and 2 (EM-1 and EM-2) have now been at the forefront of the mission design focus for the last several years. During that time, different Design Reference Missions (DRMs) were...

10. Is the Sky Really Falling? An Overview of Orbital Debris - Hull, Scott M.
Orbital debris has been a prominent topic for a while, even before the movie Gravity came out. An anti-satellite test and a collision with an operational satellite both produced large highly-publicized debris clouds within recent years. While large objects like abandoned satellites and rocket bodies may be the most recognizable and identifiable concerns, a majority of the daily threat comes from the much more numerous smaller particles. In fact, small particle penetration continues to rank among the leading risks for manned space missions to the International Space Station and beyond. How much 'stuff' is up there, where did it come...

11. Cosmic Ray Experiments and the Implications for Indirect Detection of Dark Matter - Streitmatter, Robert E.; Ormes, Jonathan F.; Mitchell, John W.
Detection of cosmic-ray antiprotons was first reported by Golden et al. in 1979 and their existence was firmly established by the BESS and IMAX collaborations in the early 1990s. Increasingly precise measurements of the antiproton spectrum, most recently from BESS-Polar and PAMELA, have made it an important tool for investigating cosmic-ray transport in the galaxy and heliosphere and for constraining dark-matter models. The history of antiproton measurements will be briefly reviewed. The current status will be discussed, focusing on the results of BESS-Polar II and their implications for the possibility of antiprotons from primordial black hole evaporation. The current results...

12. Status of Aqua MODIS On-orbit Calibration and Characterization - Erives, H.; Salomonson, V.; Barnes, W.; Xiong, X.; Chiang, K.; Che, N.; Isaacman, A.; Sun, J.
The MODIS Flight Model 1 (FM1) has been in operation for more than two years since its launch onboard the NASA's Earth Observing System (EOS) Aqua spacecraft on May 4, 2002. The MODIS has 36 spectral bands: 20 reflective solar bands (RSB) with center wavelengths from 0.41 to 2.2 micron and 16 thermal emissive bands (TEB) from 3.7 to 14.5 micron. It provides the science community observations (data products) of the Earth's land, oceans, and atmosphere for a board range of applications. Its primary on-orbit calibration and characterization activities are performed using a solar diffuser (SD) and a solar diffuser...

13. Ocean Color Measurements from Landsat-8 OLI using SeaDAS - Kuring, Norman; Bailey, Sean W.; Franz, Bryan Alden; Werdell, P. Jeremy
The Operational Land Imager (OLI) is a multi-spectral radiometer hosted on the recently launched Landsat-8 satellite. OLI includes a suite of relatively narrow spectral bands at 30-meter spatial resolution in the visible to shortwave infrared that make it a potential tool for ocean color radiometry: measurement of the reflected spectral radiance upwelling from beneath the ocean surface that carries information on the biogeochemical constituents of the upper ocean euphotic zone. To evaluate the potential of OLI to measure ocean color, processing support was implemented in SeaDAS, which is an open-source software package distributed by NASA for processing, analysis, and display...

14. Timing Studies of X Persei and the Discovery of Its Transient Quasi-periodic Oscillation Feature - Swank, J.; Serim, M. M.; Acuner, Z.; Inam,S. C.; Baykal, A.; Sahiner, S.
We present a timing analysis of X Persei (X Per) using observations made between 1998 and 2010 with the Proportional Counter Array (PCA) onboard the Rossi X-ray Timing Explorer (RXTE) and with the INTEGRAL Soft Gamma-Ray Imager (ISGRI). All pulse arrival times obtained from the RXTE-PCA observations are phase-connected and a timing solution is obtained using these arrival times. We update the long-term pulse frequency history of the source by measuring its pulse frequencies using RXTE-PCA and ISGRI data. From the RXTEPCA data, the relation between the frequency derivative and X-ray flux suggests accretion via the companion's stellar wind. However,...

15. Extension and Statistical Analysis of the GACP Aerosol Optical Thickness Record. - Liu, Li; Cairns, Brian; Rossow, William B.; Mishchenko, Michael I.; Li, Jing; Geogdzhayev, Igor V.
The primary product of the Global Aerosol Climatology Project (GACP) is a continuous record of the aerosol optical thickness (AOT) over the oceans. It is based on channel-1 and -2 radiance data from the Advanced Very High Resolution Radiometer (AVHRR) instruments flown on successive National Oceanic and Atmospheric Administration (NOAA) platforms. We extend the previous GACP dataset by four years through the end of 2009 using NOAA-17 and -18 AVHRR radiances recalibrated against MODerate resolution Imaging Spectroradiometer (MODIS) radiance data, thereby making the GACP record almost three decades long. The temporal overlap of over three years of the new NOAA-17...

16. Uncertainties in Isoprene Photochemistry and Emissions: Implications for the Oxidative Capacity of Past and Present Atmospheres and for Climate Forcing Agents - Mickley, L. J.; Alexander, B.; Murray, Lee; Kaplan, J.O.; Tai, A.P.K.; Achakulwisut, P.
Current understanding of the factors controlling biogenic isoprene emissions and of the fate of isoprene oxidation products in the atmosphere has been evolving rapidly. We use a climate-biosphere-chemistry modeling framework to evaluate the sensitivity of estimates of the tropospheric oxidative capacity to uncertainties in isoprene emissions and photochemistry. Our work focuses on trends across two time horizons: from the Last Glacial Maximum (LGM, 21 000 years BP) to the preindustrial (1770s); and from the preindustrial to the present day (1990s). We find that different oxidants have different sensitivities to the uncertainties tested in this study, with OH being the most...

17. A Persistent Feature of Multiple Scattering of Waves in the Time-Domain: A Tutorial - Lock, James A.; Mishchenko, Michael I.
The equations for frequency-domain multiple scattering are derived for a scalar or electromagnetic plane wave incident on a collection of particles at known positions, and in the time-domain for a plane wave pulse incident on the same collection of particles. The calculation is carried out for five different combinations of wave types and particle types of increasing geometrical complexity. The results are used to illustrate and discuss a number of physical and mathematical characteristics of multiple scattering in the frequency- and time-domains. We argue that frequency-domain multiple scattering is a purely mathematical construct since there is no temporal sequencing information...

18. Use of North American and European Air Quality Networks to Evaluate Global Chemistry-Climate Modeling of Surface Ozone - Naik, V.; Shindell, D. T.; Plummer, D. A.; Horowitz, L. W.; Zeng, G.; Prather, M. J.; Faluvegi, G.; Cameron-Smith, P.; Strode, S. A.; Josse, B.; Sudo, K.; Schnell, J. L.; Bergmann, D.; Nagashima, T.
We test the current generation of global chemistry-climate models in their ability to simulate observed, present-day surface ozone. Models are evaluated against hourly surface ozone from 4217 stations in North America and Europe that are averaged over 1 degree by 1 degree grid cells, allowing commensurate model-measurement comparison. Models are generally biased high during all hours of the day and in all regions. Most models simulate the shape of regional summertime diurnal and annual cycles well, correctly matching the timing of hourly (approximately 15:00 local time (LT)) and monthly (mid-June) peak surface ozone abundance. The amplitude of these cycles is...

19. Solar Signals in CMIP-5 Simulations: The Stratospheric Pathway - Mitchell, D.M.; Hood, L.; Schmidt, H.; Shindell, D.; Misios, S.; Chiodo, G.; Gray, L. J.; Matthes, K.; Tourpali, K.; Thieblemont, R.; Rozanov, E.; Krivolutsky, A.
The 11 year solar-cycle component of climate variability is assessed in historical simulations of models taken from the Coupled Model Intercomparison Project, phase 5 (CMIP-5). Multiple linear regression is applied to estimate the zonal temperature, wind and annular mode responses to a typical solar cycle, with a focus on both the stratosphere and the stratospheric influence on the surface over the period approximately 1850-2005. The analysis is performed on all CMIP-5 models but focuses on the 13 CMIP-5 models that resolve the stratosphere (high-top models) and compares the simulated solar cycle signature with reanalysis data. The 11 year solar cycle...

20. Evaluation of Long-Term Calibrations of the AVHRR Visible Radiances - Rossow, William B.; Ferrier, Joseph
Two systematic calibrations have been compiled for the visible radiances measured by the series of AVHRR instruments flown on the NOAA operational polar weather satellites: one by the International Satellite Cloud Climatology Project (ISCCP), anchored on NASA ER-2 underflights in the 1980s and early 1990s and covering the period 1981-2009, and one by the PATMOS-x project, anchored on comparisons to the MODIS instruments on the Aqua and Terra satellites in the 2000s and covering the period 1979-2010 (this result also includes calibration for the near-IR channels). Both methods have had to extend their anchor calibrations over a long series of...

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