Sunday, June 21, 2015

 

 



Soy un nuevo usuario

Olvidé mi contraseña

Entrada usuarios

Lógica Matemáticas Astronomía y Astrofísica Física Química Ciencias de la Vida
Ciencias de la Tierra y Espacio Ciencias Agrarias Ciencias Médicas Ciencias Tecnológicas Antropología Demografía
Ciencias Económicas Geografía Historia Ciencias Jurídicas y Derecho Lingüística Pedagogía
Ciencia Política Psicología Artes y Letras Sociología Ética Filosofía
 

rss_1.0 Recursos de colección

NASA Technical Reports Server (NTRS) (668,914 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 302,879

1. Phased Array GNSS Antenna for the FORMOSAT-7/COSMIC-2 Radio Occultation Mission - Meehan, Tom K.; Young, Larry E.; Turbiner, Dmitry
No abstract available

2. Wide Operating Temperature Range Electrolytes for High Voltage and High Specific Energy Li-Ion Cells - Ratnakumar, B. V.; West, W. C.; Hawng, C.; Amine, K.; Soler, J.; Smart, M. C.; Krause, F. C.
No abstract available

3. Mixed-Strategy Chance Constrained Optimal Control - Balaram, J. (Bob); Kuwata, Yoshiaki; Ono, Masahiro
No abstract available

4. Search for Cosmic-Ray-Induced Gamma-Ray Emission in Galaxy Clusters - Ballet, J.; Pesce-Rollins, M.; Kuss, M.; Barbiellini, G.; Bregeon, J.; Albert, A.; Spandre, G.; Caliandro, G. A.; Ackermann, M.; Bellazzini, R.; Brigida, M.; Caraveo, P. A.; Bloom, E. D.; Sgro, C.; Buson, S.; Tinivella, M.; Chaves, R. C. G.; Cameron, R. A.; Ajello, M.; Buehler, R.; Atwood, W. B.; Brandt, T. J.; Baldini, L.; Allafort, A.; Bastieri, D.; Bruel, P.; Bonamente, E.; Bechtol, K.; Bottacini, E.; Cavazzuti, E.
Current theories predict relativistic hadronic particle populations in clusters of galaxies in addition to the already observed relativistic leptons. In these scenarios hadronic interactions give rise to neutral pions which decay into gamma rays that are potentially observable with the Large Area Telescope (LAT) on board the Fermi space telescope. We present a joint likelihood analysis searching for spatially extended gamma-ray emission at the locations of 50 galaxy clusters in four years of Fermi-LAT data under the assumption of the universal cosmic-ray (CR) model proposed by Pinzke & Pfrommer. We find an excess at a significance of 2.7 delta, which...

5. A Triboelectric Sensor Array for Electrostatic Studies on the Lunar Surface - Johansen, Michael R.; Mackey, Paul J.; Calle, C. I.
The moons electrostatic environment requires careful consideration in the development of future lunar landers. Electrostatically charged dust was well documented during the Apollo missions to cause thermal control, mechanical, and visibility issues. The fine dust particles that make up the surface are electrostatically charged as a result of numerous charging mechanisms. The relatively dry conditions on the moon creates a prime tribocharging environment during surface operations. The photoelectric effect is dominant for lunar day static charging, while plasma electrons are the main contributor for lunar night electrostatic effects. Electrostatic charging is also dependent on solar intensity, Earth-moon relative positions, and...

6. The JPL Electronic Nose: Monitoring Air in the US Lab on the International Space Station - Lara, L. M.; Ryan, M. A.; Shevade, A. V.; Homer, M. L.; Manatt, K. S.; Kisor, A. K.; Gluck, S.; Zhou, H.
An electronic nose with a sensor array of 32 conductometric sensors has been developed at the Jet Propulsion Laboratory (JPL) to monitor breathing air in spacecraft habitat. The Third Generation ENose is designed to operate in the environment of the US Lab on the International Space Station (ISS). It detects a selected group of analytes at target concentrations in the ppm regime at an environmental temperature range of 18 - 30 oC, relative humidity from 25 - 75% and pressure from 530 to 760 torr. The monitoring targets are anomalous events such as leaks and spills of solvents, coolants or...

7. Daytime Water Detection Based on Color Variation - Matthies, Larry H.; Rankin, Arturo L.
Robust water detection is a critical perception requirement for unmanned ground vehicle (UGV) autonomous navigation. This is particularly true in wide open areas where water can collect in naturally occurring terrain depressions during periods of heavy precipitation and form large water bodies (such as ponds). At far range, reflections of the sky provide a strong cue for water. But at close range, the color coming out of a water body dominates sky reflections and the water cue from sky reflections is of marginal use. We model this behavior by using water body intensity data from multiple frames of RGB imagery...

8. Starshade Design for Occulter Based Exoplanet Missions - Walkemeyer, Phil; Polanco, Otto; Lee, Siu-Chun; Lisman, P. Douglas; Helms, Richard; Kissil, Andrew; Thomson, Mark W.
We present a lightweight starshade design that delivers the requisite profile figure accuracy with a compact stowed volume that permits launching both the occulter system (starshade and spacecraft) and a 1 to 2m-class telescope system on a single existing launch vehicle. Optimal figure stability is achieved with a very stiff and mass-efficient deployable structure design that has a novel configuration. The reference design is matched to a 1.1m telescope and consists of a 15m diameter inner disc and 24 flower-like petals with 7.5m length. The total tip-to-tip diameter of 30m provides an inner working angle of 75 mas. The design...

9. Optimization of a Multi-Stage ATR System for Small Target Identification - Edens, Western; Huntsberger, Terrance; Braun, Henry; Zhang, Yuhan; Lu, Thomas; Assad, Christopher; Chao, Tien- Hsin; Lin, Tsung-Han
An Automated Target Recognition system (ATR) was developed to locate and target small object in images and videos. The data is preprocessed and sent to a grayscale optical correlator (GOC) filter to identify possible regionsof- interest (ROIs). Next, features are extracted from ROIs based on Principal Component Analysis (PCA) and sent to neural network (NN) to be classified. The features are analyzed by the NN classifier indicating if each ROI contains the desired target or not. The ATR system was found useful in identifying small boats in open sea. However, due to "noisy background," such as weather conditions, background buildings,...

10. High-Precision Narrow Angle Astrometry with a Space-Borne Interferometer - Murphy, Dave; Milman, Mark H.
This paper develops an observing and processing scheme for narrow angle astrometry using a single baseline interferometer without the aid of "grid" stars to characterize the interferometer baseline vector in inertial space. The basic concept derives from the recognition that over a narrow field the set of fundamental unknown instrument parameters that arise because the interferometer baseline vector has large uncertainties (since there are no grid star measurements) is indistinguishable from a particular set of unobservable errors in the determination of star positions within the field. Reference stars within the narrow field of regard are used to circumvent the unobservable...

11. Microwave Radiometers from 0.6 to 22 GHz for Juno, A Polar Orbiter Around Jupiter - Oswald, J.; Chen, J.; Kitiyakara, A.; Janssen, M.; Pingree, P.; Brown, S.; Smith, S.; Hurst, K.; Maiwald, F.
A compact instrument called the MWR (MicroWave Radiometer) is under development at JPL for Juno, the next NASA New Frontiers mission, scheduled to launch in 2011. It's purpose is to measure the thermal emission from Jupiter's atmosphere at six selected frequencies from 0.6 to 22 GHz, operating in direct detection mode, in order to quantify the distributions and abundances of water and ammonia in Jupiter's atmosphere. The goal is to understand the previously unobserved dynamics of the sub-cloud atmosphere, and to discriminate among models for planetary formation in our solar system. As part of a deep space mission aboard a...

12. Terrestrial Planet Finder Interferometer: 2007-2008 Progress and Plans - Martin, S. R.; Lawson, P. R.; Lay, O. P.; Danchi, W. C.; Johnston, K. J.; Peters, R. D.; Ksendzov, A.; Gappinger, R. O.; Serabyn, E.; Booth, A. J.; Beichman, C. A.; Scharf, D. P.
This paper provides an overview of technology development for the Terrestrial Planet Finder Interferometer (TPF-I). TPF-I is a mid-infrared space interferometer being designed with the capability of detecting Earth-like planets in the habitable zones around nearby stars. The overall technology roadmap is presented and progress with each of the testbeds is summarized. The current interferometer architecture, design trades, and the viability of possible reduced-scope mission concepts are also presented.

13. Performance of the JWST/MIRI Si:As Detectors - Sukhatme, Kalyani G.; Drab, John J.; Lee, Richard A. M.; Cho, Hyung; Ressler, Michael E.; Domingo, George
The Mid-Infrared Instrument (MIRI) is a 5 to 28 micron imager and spectrometer that is slated to fly aboard the JWST in 2013. Each of the flight arrays is a 1024x1024 pixel Si:As impurity band conductor detector array, developed by Raytheon Vision Systems. JPL, in conjunction with the MIRI science team, has selected the three flight arrays along with their spares. We briefly summarize the development of these devices, then describe the measured performance of the flight arrays along with supplemental data from sister flight-like parts.

14. Brassboard Astrometric Beam Combiner (ABC) Development for the Space Interferometry Mission (SIM) - Rud, Mike; Kuan, Gary; Jeganathan, Muthu; Moore, James; Lin, Sean; Sutherland, Kristen; An, Xin
The Astrometric Beam Combiner (ABC) is a critical element of the Space Interferometry Mission (SIM) that performs three key functions: coherently combine starlight from two siderostats; individually detect starlight for angle tracking; and disperse and detect the interferometric fringes. In addition, the ABC contains: a stimulus, cornercubes and shutters for in-orbit calibration; several tip/tilt mirror mechanisms for in-orbit alignment; and internal metrology beam launcher for pathlength monitoring. The detailed design of the brassboard ABC (which has the form, fit and function of the flight unit) is complete, procurement of long-lead items is underway, and assembly and testing is expected to...

15. A Gas Management System for an Ultra Long Duration Titan Blimp - Jones, J. A.; Brooke, L.; Yavrouian, A. H.; Kerzhanovich, V. V.; Hennings, B.; Van Boeyen, R.; Mennella, J.; Hall, J. L.
This paper presents analyses, designs and experimental results for the gas management system of a hydrogen-filled blimp capable of flying in the lower atmosphere of Titan for a period of one year or more. The engineering strategy has two basic elements: first, to minimize leakage rates from the blimp envelope and ballonets; and second, to provide auxiliary subsystems to mitigate the life-limiting effects resulting from those leaks. Leak minimization is achieved through use of cryogenically compatible balloon materials and adhesives, and selection of ballonet geometries that minimize pinhole generation via folding and material fatigue. Hydrogen loss to the environment through...

16. GEO/SAMS - The Geostationary Synthetic Aperture Microwave Sounder - Lambrigtsen, Bjorn H.
The National Oceanic and Atmospheric Administration (NOAA) has for many years operated two weather satellite systems, the Polar-orbiting Operational Environmental Satellite system (POES), using low-earth orbiting (LEO) satellites, and the Geostationary Operational Environmental Satellite system (GOES), using geostationary earth orbiting (GEO) satellites. (Similar systems are also operated by other nations.) The POES satellites have been equipped with both infrared (IR) and microwave (MW) atmospheric sounders, which makes it possible to determine the vertical distribution of temperature and humidity in the troposphere even under cloudy conditions. Such satellite observations have had a significant impact on weather forecasting accuracy, especially in regions...

17. SIM PlanetQuest: Progress Report - Shao, Michael; Marr-IV, James C.; Goullioud, Renaud
SIM PlanetQuest, a micro-arcsecond astrometry space mission, has been impacted by significant changes in NASA priorities over the last two years, resulting in the mission being indefinitely delayed. The SIM team has responded by investigating alternative mission concepts based upon completed SIM technology. Several alternative mission concepts have been identified, ranging from a planets-only concept, to versions of SIM, called SIM-Lite, that still address the full breadth of SIM science envisioned by two previous National Academy Astrophysics Decadal Surveys but with lower precision and reduced throughput. These mission concepts, Planet Hunter and SIM-Lite, are significantly more affordable and may fit...

18. Real-Time Wavefront Control for the PALM-3000 High Order Adaptive Optics System - Roberts, Jennifer E.; Dekany, Richard G.; Troy, Mitchell; Bouchez, Antonin H.; Guiwits, Stephen R.; Truong, Tuan N.
We present a cost-effective scalable real-time wavefront control architecture based on off-the-shelf graphics processing units hosted in an ultra-low latency, high-bandwidth interconnect PC cluster environment composed of modules written in the component-oriented language of nesC. The architecture enables full-matrix reconstruction of the wavefront at up to 2 KHz with latency under 250 us for the PALM-3000 adaptive optics systems, a state-of-the-art upgrade on the 5.1 meter Hale Telescope that consists of a 64 x 64 subaperture Shack-Hartmann wavefront sensor and a 3368 active actuator high order deformable mirror in series with a 241 active actuator tweeter DM. The architecture can...

19. The Detection and Mitigation of RFI with the Aquarius L-Band Scatterometer - Spencer, M. W.; Freedman, A. P.; Fischman, M. A.; McWatters, D. A.; Piepmeier, J. R.
The Aquarius sea-surface salinity mission includes an L-band scatterometer to sense sea-surface roughness. This radar is subject to radio-frequency interference (RFI) in its passband from 1258 to 1262 MHz, a region also allocated for terrestrial radio location. Due to its received power sensitivity requirements, the expected RFI environment poses significant challenges. We present the results of a study evaluating the severity of terrestrial RFI sources on the operation of the Aquarius scatterometer, and propose a scheme to both detect and remove problematic RFI signals in the ocean backscatter measurements. The detection scheme utilizes the digital sampling of the ambient input...

20. High Efficiency Submillimeter-Wave Imaging Array - Llombart, Nuria; Skalare, Anders; Siegel, Peter H.; Gill, John J.
The period of a focal array is limited by the angular sampling and the f number of the system. This fact will limit the efficiency of imaging array systems to around 50%. Recently it been demonstrated that the use of a dielectric layer on top of an array of apertures can improve this efficiency limit. In this paper, we describe a similar structure that improves the efficiency in imaging applications and that it is easy to manufacture due to its compatibility with planar lithographic techniques.

Página de resultados:
 

Busque un recurso