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  • INSTRUMENTATION AND PHOTOGRAPHY  (13)
  • Aerodynamics
  • Biology
  • 2005-2009  (7)
  • 1980-1984  (14)
  • 1
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    Shot noise limited detection of OH using the technique of laser-induced fluorescence (1984)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: Nearly shot-noise limited detection of OH using the technique of laser-induced fluorescence is reported. A LIDAR configuration is used to excite fluoresence in a large volume and a narrow-bandwidth interference filter provides spectral discrimination. This arrangement alleviates the effect of ozone interference and facilitates image processing at relatively close distances. The detection limit is determined mainly by the short-noise of the solar background. Ground-based measurements in Dearborn indicate a detection limit of better than 1 x 10 to the 6th power OH/cubic cm over a forty-minute acquisition period. Under favorable conditions, a comparable detection limit was also observed for airborne measurements.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics (ISSN 0003-6935); 23; 4076-408
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    NASA TECHNICAL REPORTS
  • 2
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    Multiband selection device (1984)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: Current science projections for future earth-imaging instruments indicate the need for as many as 25 spectral bands, with bandwidths as narrow as 20 nanometers. The desire for a multiplicity of bands has led researchers to study various spectrally dispersive instrument designs as a means of providing the desired future capability. These instrument designs, however, are costly, complex, and of high technical risk. This paper describes a 'multiband selection device' containing several spectral filters that can be placed at the exit faces of a broadband multiport beam splitter and thereby provide a multiplicity of spectral bands with a high degree of spatial coregistration while utilizing state-of-the-art linear array detectors. Fabrication of the multiband selection device has been successfully accomplished, and the design and test results are described.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
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    NASA TECHNICAL REPORTS
  • 3
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    Multiwavelength analyzer for the determination of diffusion lengths (1983)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: The minority carrier diffusion length Ln in the base or substrate region is an important parameter which governs a solar cell's performance. The present investigation is concerned with the development of a multiwavelength analyzer (MWA) technique for the nondestructive spatial testing of polycrystalline solar cells. The MWA method is based on the utilization of the short-circuit current generated by two or more light-emitting diodes (LEDs) operating at different wavelengths and modulated 180 deg out-of-phase. For a determination of Ln by the MWA technique, it is necessary to know the value of the absorption coefficient.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Solar Cells (ISSN 0379-6787); 9; Sept
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    NASA TECHNICAL REPORTS
  • 4
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    Nuclear Science Symposium, 29th, and Symposium on Nuclear Power, 14th, Washington, DC, October 20-22, 1982, Proceedings (1983)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: High-energy radiation detectors suitable for balloon-borne or space-based radiation event studies are described. The employment of NaI(Tl) scintillator bars for gamma ray detection is outlined, and the development of a fluorescent gated gas-filled scintillation proportional counter is reported. A high throughput nondispersive hard X ray spectrograph with angular resolution for cosmic bursts, transients, and sources has been constructed. Features of a sealed high pressure xenon filled imaging proportional counter with a 30 sq cm sensitive area are explored. Finally, the various radiation effects on electronic circuitry in a space environment are defined, and an MOS dosimeter for assaying the cumulative radiation flux in a spacecraft due to ambient conditions is characterized.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
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  • 5
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    A simplified GPS C/A reciever front end with low noise performance (1984)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: A redesign of the antenna electronics package for the NBS/GPS C/A receiver has resulted in significantly reduced cost and improved performance. Major improvements include a simplified and more reliable multiplier/mixer, elimination of all twelve piston trimmer tuning capacitors in the original design, elimination of expensive bandpass filters, less expensive antenna and a simplified packaging scheme.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Goddard Space Flight Center Proc. of the 16th Ann. Precise Time and Time Interval (PTTI) Appl. and Planning Meeting; p 467-474
    Format: application/pdf
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  • 6
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    Portable dynamic pressure generator for static and dynamic calibration of in situ pressure transducers (1983)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A portable dynamic pressure generator was developed to meet the requirements of determining the dynamic sensitivities of in situ pressure transducers at low frequencies. The device is designed to operate in a frequency range of 0 to 100 Hz, although it was only tested up to 30 Hz, and to generate dynamic pressures up to 13.8 kPa (2 psi). A description of the operating characteristics and instrumentation used for pressure, frequency, and displacement measurements is given. The pressure generator was used to statically and dynamically calibrate transducers. Test results demonstrated that a difference an exist between the static and dynamic sensitivity of a transducer, confirming the need for dynamic calibrations of in situ pressure transducers.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA-TM-85687 , NAS 1.15:85687
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  • 7
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    Proposed fast-response oxygen monitoring and control system for the Langley 8-foot high-temperature tunnel (1983)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A fast-response oxygen monitoring and control system, based on a Y2O3-stabilized ZrO2 sensor, was developed and tested in the laboratory. The system is capable of maintaining oxygen concentration in the CH4-O2-air combustion product gases at 20.9 + or - 1.0 percent. If the oxygen concentration in the exhaust stream differs from that in normal air by 25 percent or more, an alarm signal is provided for automatic tunnel shutdown. The overall prototype system response time was reduced from about 1 sec in the original configuration to about 0.2 sec. The basis of operation and the results of laboratory tests of the system are described.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA-TP-2218 , L-15666 , NAS 1.60:2218
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 8
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    Photofragmentation-laser induced fluorescence - A new method for detecting atmospheric trace gases (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: A new method for the in situ detection of nonfluorescing molecular species is proposed: photofragmentation-laser induced fluorescence (PF-LIF). In this approach, the species to be detected is first laser photolyzed at a wavelength lambda (1), producing one or more vibrationally excited photofragments. Before vibrational relaxation occurs, one of these photofragments is pumped into a bonding excited state by a second laser pulse centered at wavelength lambda (2). Fluorescence is sampled at a wavelength lambda (3), where lambda (3) is less then lambda (2) and lambda (1). This pumping configuration thus permits massive discrimination against Rayleigh and Raman scattering as well as white noise fluorescence from the laser wavelengths lambda (1) and lambda (2). The technique should be both highly sensitive and selective for numerous atmospheric trace gases. Specific sampling schemes for detecting NO2, NO3, and HNO2 are proposed. Various noise sources and chemical interferences are discussed. Specific calculations that estimate the sensitivity of the PF-LIF system for detecting NO2, NO3, and HNO2 are given.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics; 19; Nov. 1
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  • 9
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    A new thermal radiation detector using optical heterodyne detection of absorbed energy (1983)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The operating principles of a new kind of room-temperature thermal radiation detector are described. In this device modulated light heats a gas, either directly or by conduction from a thin absorbing membrane, and the resultant change in density of the gas is detected by optical heterodyning. The performance of a membrane device of this kind agrees well with the predictions of theory.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Infrared Physics (ISSN 0020-0891); 23; 177-182
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    NASA TECHNICAL REPORTS
  • 10
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    Flight Test Determined Aerodynamics Force and Moment Characteristics of the X-43A Research Vehicle at Mach 7.0 (2006)
    In:  Other Sources
    Details
    Publication Date: 2019-07-19
    Description: The second flight of the HYPER-X Program afforded a unique opportunity to determine the aerodynamic force and moment characteristics of an airframe integrated scramjet powered aircraft in hypersonic flight. These data were gathered via a repeated series of pitch, yaw, and roll doublets, frequency sweeps, and pull-up/push-over maneuvers performed throughout the X-43A cowl-closed descent phase. The subject flight research maneuvers were conducted in a Mach number range of 6.8 to 0.95 at altitudes from 92,000 ft to sea level. In this flight regime, the dynamic pressure varied from 1300 psf to 400 psf with angle-of-attack ranging from 0 deg to 14 deg. The flight-extracted aerodynamics were compared with pre-flight predictions based on wind tunnel test data. The X-43A flight-derived axial force was found to be 10 to 15 percent higher than prediction. Under-predictions of similar magnitude were observed for the normal force. For Mach numbers greater than 4, the X-43A flight-derived stability and control characteristics resulted in larger than predicted static margins, with the largest discrepancy approximately 5-inches forward along the X(CG) at Mach 6. This would result in less static margin in pitch. The X-43A predicted lateral-directional stability and control characteristics matched well with flight data when allowance was made for the high uncertainty in angle-of-sideslip.
    Keywords: Aerodynamics
    Type: DFRC-459
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