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  • Other Sources  (370)
  • Spacecraft Propulsion and Power  (156)
  • Electronics and Electrical Engineering  (133)
  • Aircraft Design, Testing and Performance
  • Female
  • 2010-2014  (198)
  • 1995-1999  (164)
  • 1950-1954  (5)
  • 1940-1944  (3)
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  • 1
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    Comparison of Light Emitting Diodes (LED) and Fluorescent Light on Suppression of Pineal Melatonin in the Rat (1997)
    In:  Other Sources
    Details
    Publication Date: 2019-07-18
    Description: To validate a novel LED array for use in animal habitat lighting by comparing its effectiveness to cool-white fluorescent (CWF) lighting in suppressing pineal gland melatonin. Male Sprague-Dawley rats, 175-200 g, were maintained under control conditions for 2 weeks (food and water ad lib, 12L: 12D CWF, 18 uW/square cm). Dark adapted animals (animals before lights on) were exposed to 5 min of LED or CWF light of similar spectral power distribution. Two groups of rats (LED vs. CWF) were compared at 5 light intensities (100, 40, 1, 1.0, and 0. 1 lux). A control group was placed into the exposure apparatus but not exposed to light. After exposure, pineal glands were rapidly removed and assayed for melatonin by RIA. Results. The dark-exposed control groups matched with the 5 intensity groups (100, 40, 10, 1.0, and 0.1 lux) showed mean + SEM pineal melatonin values of 1167 +/- 136, 1569 +/- 126, 353 +/- 34, 650 +/- 124, and 464 +/- 85, pg/ml respectively. The corresponding CWF exposure data were 393 1 41, 365 +34, 257 +/- 13, 218 +/- 42, and 239 +/- 71 pg/ml, respectively. Corresponding LED exposure data were 439 +/- 25, 462 +/- 50, 231 +/- 6, 164 +/- 12, and 158 +/- 12 pg/ml, respectively. Rats exposed to both experimental light conditions at all illuminances studied showed significant melatonin suppression (p less than 0.01, ANOVA). In no case was the melatonin suppression induced by LED illuminance significantly different from the melatonin suppression elicited by the same intensity of CWF light. The results show that a novel LED light source can suppress pineal melatonin equal to that of a conventional CWF light source.
    Keywords: Electronics and Electrical Engineering
    Type: International Congress on Chronobiology; Sep 07, 1997 - Sep 11, 1997; Paris; France
    Format: text
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  • 2
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    Single Pixel Characterization of X-Ray TES Microcalorimeter Under AC Bias at MHz Frequencies (2012)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: In this paper we present the progress made at SRON in the read-out of GSFC x-ray transition-edge sensor (TES) micro-calorimeters in the frequency domain. The experiments reported so far, whose aim was to demonstrate an energy resolution of 2eV at 6 keV with a TES acting as a modulator, were carried out at frequencies below 700 kHz using a standard flux locked loop (FLL) SQUID read-out scheme. The TES read-out suffered from the use of sub-optimal circuit components, large parasitic inductances, low quality factor resonators and poor magnetic field shielding. We have developed a novel experimental set-up, which allows us to test several read-out schemes in a single cryogenic run. In this set-up, the TES pixels are coupled via superconducting transformers to 18 high-Q lithographic LC filters with resonant frequencies ranging between 2 and 5 MHz. The signal is amplified by a two-stage SQUID current sensor and baseband feedback is used to overcome the limited SQUID dynamic range. We study the single pixel performance as a function of TES bias frequency, voltage and perpendicular magnetic field.
    Keywords: Electronics and Electrical Engineering
    Type: GSFC.ABS.01036.2012 , Applied Superconductivity Conference; Oct 07, 2012 - Oct 11, 2012; Portland, OR; United States
    Format: application/pdf
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  • 3
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    Solar Thermal Upper Stage Liquid Hydrogen Pressure Control Testing and Analytical Modeling (2012)
    In:  CASI
    Details
    Publication Date: 2019-07-12
    Description: The demonstration of a unique liquid hydrogen (LH2) storage and feed system concept for solar thermal upper stage was cooperatively accomplished by a Boeing/NASA Marshall Space Flight Center team. The strategy was to balance thermodynamic venting with the engine thrusting timeline during a representative 30-day mission, thereby, assuring no vent losses. Using a 2 cubic m (71 cubic ft) LH2 tank, proof-of-concept testing consisted of an engineering checkout followed by a 30-day mission simulation. The data were used to anchor a combination of standard analyses and computational fluid dynamics (CFD) modeling. Dependence on orbital testing has been incrementally reduced as CFD codes, combined with standard modeling, continue to be challenged with test data such as this.
    Keywords: Spacecraft Propulsion and Power
    Type: NASA/TP-2012-217469 , M-1345
    Format: application/pdf
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  • 4
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    Helicon Plasma Source Optimization Studies for VASIMR (1999)
    In:  Other Sources
    Details
    Publication Date: 2019-07-17
    Description: A helicon plasma source at Oak Ridge National Laboratory is being used to investigate operating scenarios relevant to the VASIMR (VAriable Specific Impulse Magnetoplasma Rocket). These include operation at high magnetic field (〉 = 0.4 T), high frequency (〈= 30 MHz), high power (〈 = 3 kW), and with light ions (He+, H+). To date, He plasmas have been produced with n(sub e0) = 1.7 x 10(exp 19)/cu m (measured with an axially movable 4mm microwave interferometer), with Pin = I kW at f = 13.56 MHz and absolute value of B(sub 0) = 0.16 T. In the near future, diagnostics including a mass flow meter and a gridded energy analyzer array will be added to investigate fueling efficiency and the source power balance. The latest results, together with modeling results using the EMIR rf code, will be presented.
    Keywords: Spacecraft Propulsion and Power
    Type: Plasma Propulsion Physics Mini Conference; Nov 15, 1999 - Nov 19, 1999; Seattle, WA; United States
    Format: text
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  • 5
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    Development of Modeling Approaches for Nuclear Thermal Propulsion Test Facilities (2014)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: No abstract available
    Keywords: Spacecraft Propulsion and Power
    Type: SSTI-8080-0069 , Nuclear and Emerging Technologies for Space (NETS) Conference; Feb 24, 2014 - Feb 26, 2014; Bay Saint Louis, MS; United States
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  • 6
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    Solar Sail Propulsion: Enabling New Capabilities for Heliophysics (2010)
    In:  CASI
    Details
    Publication Date: 2019-07-12
    Description: Solar sails can play a critical role in enabling solar and heliophysics missions. Solar sail technology within NASA is currently at 80% of TRL-6, suitable for an in-flight technology demonstration. It is conceivable that an initial demonstration could carry scientific payloads that, depending on the type of mission, are commensurate with the goals of the three study panels of the 2010 Heliophysics Survey. Follow-on solar sail missions, leveraging advances in solar sail technology to support Heliophysics Survey goals, would then be feasible. This white paper reports on a sampling of missions enabled by solar sails, the current state of the technology, and what funding is required to advance the current state of technology such that solar sails can enable these missions
    Keywords: Spacecraft Propulsion and Power
    Type: M11-0117
    Format: application/pdf
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  • 7
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    Performance Comparison Between NiH2 Dry Sinter and Slurry Electrode Cells (1997)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: The electrical and thermal performance of dry sinter and slurry process electrode cells manufactured for the Hubble Space Telescope (HST) batteries have been characterized for a matrix of operating conditions over the temperature range from 14 to 86 F at various charge control levels. The dry sinter process electrode cells tested are similar to the onboard HST NiH2 cells. The slurry process electrode cells were developed to be less susceptible to electrode expansion and impedance changes with life. Both cell types were impregnated by the aqueous electrochemical process. Test conditions included standard capacity tests and electrical cycling using 96-minute cycling regimens incorporating gr depth-of-discharge (DOD) cycles. The dry sinter process electrodes have higher operating capacities to 1.20V/cell, but both electrode types have similar heat dissipation for the conditions tested. The results of the testing included cyclic heat generation during a typical 96-minute cycle, operating capacity data vs. cutoff voltage to generate a temperature-compensated voltage curve, and voltage characteristics suitable to develop a voltage prediction model. Analysis of data shows differences in the discharge voltage plateaus operating conditions evaluated. This is the basis for recommended changes in the battery charge control.
    Keywords: Electronics and Electrical Engineering
    Type: Battery Applications and Advances; Unknown
    Format: application/pdf
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  • 8
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    Prediction Accuracy of Error Rates for MPTB Space Experiment (1998)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: This paper addresses the accuracy of radiation-induced upset-rate predictions in space using the results of ground-based measurements together with standard environmental and device models. The study is focused on two part types - 16 Mb NEC DRAM's (UPD4216) and 1 Kb SRAM's (AMD93L422) - both of which are currently in space on board the Microelectronics and Photonics Test Bed (MPTB). To date, ground-based measurements of proton-induced single event upset (SEM cross sections as a function of energy have been obtained and combined with models of the proton environment to predict proton-induced error rates in space. The role played by uncertainties in the environmental models will be determined by comparing the modeled radiation environment with the actual environment measured aboard MPTB. Heavy-ion induced upsets have also been obtained from MPTB and will be compared with the "predicted" error rate following ground testing that will be done in the near future. These results should help identify sources of uncertainty in predictions of SEU rates in space.
    Keywords: Electronics and Electrical Engineering
    Type: Nuclear Instruments and Methods in Physics Research
    Format: application/pdf
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  • 9
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    Analytical Fuselage and Wing Weight Estimation of Transport Aircraft (1996)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A method of estimating the load-bearing fuselage weight and wing weight of transport aircraft based on fundamental structural principles has been developed. This method of weight estimation represents a compromise between the rapid assessment of component weight using empirical methods based on actual weights of existing aircraft, and detailed, but time-consuming, analysis using the finite element method. The method was applied to eight existing subsonic transports for validation and correlation. Integration of the resulting computer program, PDCYL, has been made into the weights-calculating module of the AirCraft SYNThesis (ACSYNT) computer program. ACSYNT has traditionally used only empirical weight estimation methods; PDCYL adds to ACSYNT a rapid, accurate means of assessing the fuselage and wing weights of unconventional aircraft. PDCYL also allows flexibility in the choice of structural concept, as well as a direct means of determining the impact of advanced materials on structural weight. Using statistical analysis techniques, relations between the load-bearing fuselage and wing weights calculated by PDCYL and corresponding actual weights were determined.
    Keywords: Aircraft Design, Testing and Performance
    Type: NASA-TM-110392 , A-961451 , NAS 1.15:110392
    Format: application/pdf
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  • 10
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    Dynamic Black-Level Correction and Artifact Flagging in the Kepler Data Pipeline (2013)
    In:  CASI
    Details
    Publication Date: 2019-07-19
    Description: Instrument-induced artifacts in the raw Kepler pixel data include time-varying crosstalk from the fine guidance sensor (FGS) clock signals, manifestations of drifting moir pattern as locally correlated nonstationary noise and rolling bands in the images which find their way into the calibrated pixel time series and ultimately into the calibrated target flux time series. Using a combination of raw science pixel data, full frame images, reverse-clocked pixel data and ancillary temperature data the Keplerpipeline models and removes the FGS crosstalk artifacts by dynamically adjusting the black level correction. By examining the residuals to the model fits, the pipeline detects and flags spatial regions and time intervals of strong time-varying blacklevel (rolling bands ) on a per row per cadence basis. These flags are made available to downstream users of the data since the uncorrected rolling band artifacts could complicate processing or lead to misinterpretation of instrument behavior as stellar. This model fitting and artifact flagging is performed within the new stand-alone pipeline model called Dynablack. We discuss the implementation of Dynablack in the Kepler data pipeline and present results regarding the improvement in calibrated pixels and the expected improvement in cotrending performances as a result of including FGS corrections in the calibration. We also discuss the effectiveness of the rolling band flagging for downstream users and illustrate with some affected light curves.
    Keywords: Electronics and Electrical Engineering
    Type: M13-3027 , Kepler Science Conference; Nov 04, 2013 - Nov 08, 2013; Mountain View, CA; United States
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