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  • General Chemistry  (2,051)
  • INSTRUMENTATION AND PHOTOGRAPHY  (754)
  • Cell & Developmental Biology  (744)
  • BIOTECHNOLOGY
  • 1985-1989
  • 1980-1984  (1,699)
  • 1970-1974  (2,163)
  • 1983  (1,699)
  • 1971  (2,163)
Collection
Keywords
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Years
  • 1985-1989
  • 1980-1984  (1,699)
  • 1970-1974  (2,163)
Year
  • 1
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    Si:Bi array detectors and astronomical applications of the Goddard 10 micron camera (1983)
    In:  CASI
    Details
    Publication Date: 2004-12-04
    Description: An improved 4 to 18 micron array camera system was developed at NASA Goddard SFC for astronomical photometry, using an Aerojet Electro Systems Corp. 16 x 16 Si:Bi accumulation mode charge injection device (AMCID) which could be suitable for eventual low-background spaceflight applications. An astronomical observing program using this device was carried out as a collaboration between NASA Goddard (Infrared and Radio Astronomy Branch and Micro Electronics Branch), the Harvard/Smithsonian Center for Astrophysics, and Steward Observatory of the University of Arizona. In 1983 the camera system was revised, and a new Aeroject Si:Bi array with 16 x 16 active pixels was obtained from NASA/Ames Research Center as part of a new scientific collaboration between the Ames and Goddard infrared array research groups. The 16 x 16 device had sufficiently good sensitivity, uniformity and noise characteristics to be used for successful observations at the Mt. Lemmon 60 and 61 inch telescopes in May 1983. Complete laboratory characterization of the 16 x 16 array was carried out in summer of 1983. Initial results indicate that this detector has sensitivity and noise characteristics comparable to other devices from the same generation of Aerojet arrays.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Ames Research Center, Infrared Detector Technology Workshop; 12 p
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  • 2
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    Heterodyne frequency measurements and frequency calibration standards for tunable diode lasers (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: New frequency calibration tables are required to keep abreast of the resolution attainable by currently available tunable lasers. One key to the generation of tables with requisite accuracy involves accurate heterodyne frequency measurements; another key consists of reliable fitting and analysis. Coordinated activity in NBS involves selection of suitable molecular calibration candidates, their frequency measurement and analysis, and dissemination of the results in the form of frequency calibration tables. Current status of these efforts is described.
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  • 3
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    Optogalvanic photodetachment spectroscopy (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A new extension to optogalvanic spectroscopy, in which electrons detached from negative ions formed in the discharge are observed as a function of incident laser wavelength, has been developed. The determination of the electron affinities of I(-) and Cl(-) atomic ions is described. The potential of the technique for studying the spectroscopy of molecular negative ions is also discussed.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Journal de Physique (ISSN 0449-1947); 44; C7-461 t
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  • 4
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    Nd:YAG holographic interferometer for aerodynamic research (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A holographic interferometer system has been installed in the NASA Ames 2- by 2-Foot Transonic Wind Tunnel. The system incorporates a modern 10 pps, Nd:YAG pulsed laser which provides reliable operation and is easy to align. The spatial filtering requirements of the unstable resonator beam are described, as well as the integration of the system into the existing schlieren system. A two-plate holographic interferometer is used to reconstruct flow field data. For static wind tunnel models, the single exposure holograms are recorded in the usual manner; however, for dynamic models such as oscillating airfoils, synchronous laser hologram recording is used.
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  • 5
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    Differential absorption lidar technique for measurement of the atmospheric pressure profile (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A new two-wavelength lidar technique for remotely measuring the pressure profile using the trough absorption region between two strong lines in the oxygen A band is described. The theory of integrated vertical path, differential ranging, and horizontal-path pressure measurements is given, with methods to desensitize and correct for temperature effects. The properties of absorption troughs are described and shown to reduce errors due to laser frequency jitter by up to two orders of magnitude. A general analysis, including laser bandwidth effects, demonstrates that pressure measurements with an integrated-vertical-path technique are typically fifty times more accurate than with a differential ranging technique. Simulations show 0.1-0.3 percent accuracy for ground and Shuttle-based pressure-profile and surface-pressure experiments.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics (ISSN 0003-6935); 22; 3759-377
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  • 6
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    Airborne detection of oceanic turbidity cell structure using depth-resolved laser-induced water Raman backscatter (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Airborne laser-induced, depth-resolved water Raman backscatter is useful in the detection and mapping of water optical transmission variations. This test, together with other field experiments, has identified the need for additional field experiments to resolve the degree of the contribution to the depth-resolved, Raman-backscattered signal waveform that is due to (1) sea surface height or elevation probability density; (2) off-nadir laser beam angle relative to the mean sea surface; and (3) the Gelbstoff fluorescence background, and the analytical techniques required to remove it. When converted to along-track profiles, the waveforms obtained reveal cells of a decreased Raman backscatter superimposed on an overall trend of monotonically decreasing water column optical transmission.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics (ISSN 0003-6935); 22; 3778-378
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  • 7
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    Description and overview of an instrument designed to measure line-of-sight delay due to water vapor (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Eight dual channel microwave radiometers were constructed as a research and development effort for the Crustal Dynamics Project and the Deep Space Network. These instruments, known as water vapor radiometers, are primarily intended to demonstrate that the variable path delay imposed by atmospheric water vapor can be calibrated in microwave tracking and distance measuring systems but could also be used in other applications involving moist air meteorology and propagation studies. They are being deployed to various stations and observatories that participate in Very Long Baseline Interferometry experiments. The development history of these instruments are reviewed, the theory of operation and overall design considerations are outlined, and the instrumental parameters and performance characteristics are described.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: The Telecommun. and Data Acquisition Rept.; p 1-19
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  • 8
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    Spacelab high density digital recorders (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The design and performance of the high-density digital recorder (HDDR) developed for use at the NASA centers (KSC, JSC, and GSFC) and at the JPL to store and retrieve 50-Mb/s PCM data streams from the Spacelab experiments are reported. The recording reproduction, and transport requirements are reviewed; and the design solutions adopted in the final version of the HDDR are described, incuding three-position-modulation and Y-phase encoding, microprocessor-controlled automatic bit synchronization and equalization, cyclic-redundancy-check error detection and correction, clock regeneration, data and clock variations, tape-speed control, and EEE-488 remote control. Reliable performance, with bit error rates 1 in 10 to the 10th forward and 1 in 10 to the 9th reverse or better and packing density up to 50 percent greater than that obtainable using conventional codes, is reported after 1.5 years of service.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
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  • 9
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    Design philosophy of the Jet Propulsion Laboratory infrared detector test facility (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: To support the development of advanced infrared remote sensing instrumentation using line and area arrays, a test facility has been developed to characterize the detectors. The necessary performance characteristics of the facility were defined by considering current and projected requirements for detector testing. The completed facility provides the desired level of detector testing capability as well as providing ease of human interaction.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
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  • 10
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    Comparison of measurements by different instruments of the far-infrared reflectance of rough, optically black coatings (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Two comparisons of available specular infrared measurements using identical or very similar coatings reveal that specular BRDF (bidirectional reflectance distribution function) measurements of rough coatings are comparable but that simple measured reflectances are not. This is seen as indicating that the diffuse component of the measured specular reflectance is significantly larger than that of the specular component. It is noted that the diffuse component of the measurement is a convolution of the intrinsic directional reflectivity of the surface with the instrument function and that because the value of that function increases at the wavelengths under consideration, the diffuse component is larger than would otherwise be expected. The BRDF normalization is found to cause a primitive deconvolution of the instrument function and to produce a quantity that is approximately equal to the mean intrinsic directional reflectivity very near the specular direction. The analysis and comparison of data reveal that nonspecular BRDF measurements at angles well outside the instrument function can be calibrated as well by an image of the source upon the detector as by reference to a known surface.
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  • 11
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    CO2 DIAL sensitivity studies for measurements of atmospheric trace gases (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: An analysis is presented of the accuracy of infrared differential absorption lidar (DIAL) measurements of trace constituents in the atmosphere. Expressions are derived for the signal-to-noise ratios applicable in the detection of a signal from a scattering cell for the cases of single-detection heterodyne detection and direct detection. Results of computer simulations of the expectation value of the measured return for various measurement conditions are presented which illustrate the sensitivities of plume measurements for horizontal range-resolved and vertical content measurements of NH3 in heterodyne and direct detection. Advantages for long-range measurements of the use of rare isotope laser frequencies, tuning by collision broadening, and closely spaced on and off frequencies are pointed out.
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  • 12
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    Coherent CO2 lidar systems for remote atmospheric measurements (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Several examples of applications of coherent CO2 Doppler lidar systems are summarized to illustrate the potential of these systems. The applications discussed include the use of continuous-wave systems for detecting and tracking aircraft wake vortices, transverse velocity measurements, and measurements of mass flow rates of high stack emissions. The use of pulsed coherent lidars is illustrated by applications involving the measurement of thunderstorm gust fronts, the measurement of wind profiles, and clear air turbulence detection. Following a summary of previous efforts, some current programs are reviewed. These include investigations into two-dimensional wind field measurements, atmospheric backscatter measurements, transverse velocity measurements, and the feasibility of space operations.
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  • 13
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    The NASA/Goddard balloon borne lidar system (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The present investigation represents a part of a NASA program which is concerned with a study regarding the seriousness of man-made stratospheric ozone depletion. Such a depletion could possibly be caused by exhaust gases of aircraft at high altitudes or the release of chlorofluorocarbons into the lower atmosphere. A balloon-borne optical radar system was employed to conduct ozone measurements in the altitude region from 21 to 36 km and hydroxyl radical measurements in the region from 33 to 36 km. The hydroxyl radical was determined by making use of a procedure which is based on fluorescence induced by laser radiation. The technique of differential absorption lidar (DIAL) was used to measure ozone. According to this technique, two wavelengths are transmitted simultaneously and their backscattered intensities are measured. the obtained results show that optical radar represents an effective tool for stratospheric investigations.
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  • 14
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    Signal averaging limitations in heterodyne- and direct-detection laser remote sensing measurements (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The improvement in measurement uncertainty brought about by the averaging of increasing numbers of pulse return signals in both heterodyne- and direct-detection lidar systems is investigated. A theoretical analysis is presented which shows the standard deviation of the mean measurement to decrease as the inverse square root of the number of measurements, except in the presence of temporal correlation. Experimental measurements based on a dual-hybrid-TEA CO2 laser differential absorption lidar system are reported which demonstrate that the actual reduction in the standard deviation of the mean in both heterodyne- and direct-detection systems is much slower than the inverse square-root dependence predicted for uncorrelated signals, but is in agreement with predictions in the event of temporal correlation. Results thus favor the use of direct detection at relatively short range where the lower limit of the standard deviation of the mean is about 2 percent, but advantages of heterodyne detection at longer ranges are noted.
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  • 15
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    Atmospheric pressure and temperature profiling using near IR differential absorption lidar (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The present investigation is concerned with differential absorption lidar techniques for remotely measuring the atmospheric temperature and pressure profile, surface pressure, and cloud top pressure-height. The procedure used in determining the pressure is based on the conduction of high-resolution measurements of absorption in the wings of lines in the oxygen A band. Absorption with respect to these areas is highly pressure sensitive in connection with the mechanism of collisional line broadening. The method of temperature measurement utilizes a determination of the absorption at the center of a selected line in the oxygen A band which originates from a quantum state with high ground state energy.
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  • 16
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    Remote detection of gases by gas correlation spectroradiometry (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The present investigation is concerned with the application of a pressure modulated radiometer (PMR) to the remote sensing of trace amounts of gases in the atmospheres as well as to the direct measurement of upper atmospheric winds. The PMR operates as a gas correlation spectrometer. Compared to conventional gas correlation parameters, it has some advantages which are related to greater versatility and the employment of a simpler method for maintaining electrical/optical balance. The PMR has a high sensitivity in connection with its essentially very high effective resolution. It represents a passive system and emits no radiation. A PMR is flown on Nimbus 6 which was launched in 1975. The instrument has also been used on the Nimbus 7 satellite and the Tiros N satellite.
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  • 17
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    Airborne remote sensing measurements with a pulsed CO2 DIAL system (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The present investigation is concerned with an optical radar instrument which has been developed for airborne remote sensing of atmospheric trace species at infrared wavelengths. The instrument makes use of compact, pulsed carbon dioxide lasers. It was designed for conducting differential absorption lidar (DIAL) measurements. The backscatter of laser pulse energy from the ocean and terrain surface is utilized to determine trace species column content. The instrument, which is carried by the NASA P3 aircraft, is used in a flight test program started in July 1981. The results obtained with the instrument in this program are discussed, taking into account ocean surface backscatter statistics, the ratio of ocean to terrain backscatter, the dual-wavelength correlation coefficient, the dual-wavelength cross-covariance, and the dependence of un-correlated noise variance on the mean backscatter signal.
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  • 18
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    Balloon-borne diode-laser absorption spectrometer for measurements of stratospheric trace species (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: An instrument has been designed for the measurement of stratospheric trace species which utilizes tunable infrared diode lasers as sources for sensitive in situ absorption spectroscopy in selected wavelength regions. This instrument, the Balloon-Borne Laser In Situ Sensor (BLISS), is a high-resolution absorption spectrometer designed to provide measurements of the concentrations of stratospheric species and their diurnal variations. The instrument employs second-harmonic detection of the absorption of tunable diode laser (TDL) radiation (3-30 microns) in a 1 km path length defined by a retroreflector lowered 0.5 km below the BLISS gondola. Retroreflector tracking under microprocessor control is obtained using a He-Ne laser and coaligned TV camera with CID imaging. Simultaneous measurements of molecular species in the 20-40 km altitude range will be performed using four TDLs, with the predicted minimum-detectable mixing ratio at 30 km being typically less than or equal to 0.1 ppbv.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics (ISSN 0003-6935); 22; Sept. 1
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  • 19
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    New technological developments for the remote detection of atmospheric hydroxyl radicals (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: New developments in the areas of narrowband tunable excimer lasers, high-resolution high-rejection optical filters, and wavelength measurement devices are considered for application to the remote sensing of atmospheric hydroxyl radicals. The conclusion is that an increase in the SNR of 10,000 could readily be gained through the use of these new devices. Also, considerable reductions in size and electrical energy consumption could be realized.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics (ISSN 0003-6935); 22; Sept. 1
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  • 20
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    Frequency-doubled CO2 lidar measurement and diode laser spectroscopy of atmospheric CO2 (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A lidar instrument based on pulsed frequency-doubled carbon-dioxide lasers has been used at 4.88 microns for remote sensing of atmospheric carbon dioxide. A tunable-diode laser spectrometer provided the high-resolution spectroscopic data on carbon-dioxide line strength and line broadening needed for an accurate differential absorption measurement. Initial field measurements are presented, and instrument improvements necessary for accurate carbon dioxide measurement are discussed.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics (ISSN 0003-6935); 22; Sept. 1
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  • 21
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    An all fiber-optic sensor for surface acoustic wave measurements (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A surface acoustic wave (SAW) sensor constructed from single-mode fiber-optic components is described. An analysis of reciprocal and nonreciprocal modes of operation of the sensor is presented. Results from measurements on a variety of SAW devices illustrate the use of the sensor. The amplitude sensitivity is 0.0003 A for an integration time of 0.1 s.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Journal of Lightwave Technology (ISSN 0733-8724); LT-1; June 198
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  • 22
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    Environmental data display (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Methods for using a combination of computer-generated color graphics and image processing techniques to display a large data base of environment information are described. The data source can be either field data or mathematical models, reduced to summary statistics that characterize the data field as a whole. Sharp gradients are plotted into contour plots, which can also feature shades, degree of brightness, and saturation levels for fine-tuning the image. The basic concepts of digital image processing are reviewed, including location of the pixels, intensity mapping operations, pseudocolor enhancements, neighborhood averaging, and smoothing. Sample applications are presented in terms of emissions and air quality distributions over the south coast air basin of southern California.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Environmental Science and Technology (ISSN 0013-936X); 17; Feb. 198
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  • 23
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    A nonintrusive laser interferometer method for measurement of skin friction (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A method is described for monitoring the changing thickness of a thin oil film subject to an aerodynamic shear stress using two focused laser beams. The measurement is then simply analyzed in terms of the surface skin friction of the flow. The analysis includes the effects of arbitrarily large pressure and skin friction gradients, gravity, and time varying oil temperature. It may also be applied to three dimensional flows with unknown direction. Applications are presented for a variety of flows, including two dimensional flows, three dimensional swirling flows, separated flow, supersonic high Reynolds number flows, and delta wing vortical flows. Previously announced in STAR as N83-12393
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Experiments in Fluids (ISSN 0723-4864); 1; 1, 19; 1983
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  • 24
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    The function and response of an improved stratospheric condensation nucleus counter (1983)
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    Publication Date: 2011-08-18
    Description: An improved condensation nucleus counter (CNC) for use in the stratosphere is described. The University of Minnesota CNC (UMCNC) has a sequential saturator and condenser and uses n-butyl alcohol as the working fluid. The use of a coaxial saturator flow, with aerosol in the center and filtered, alcohol-laden air around it, speeds the response of this instrument and improves its stability as pressure changes. The counting efficiency has been studied as a function of particle size and pressure. The UMCNC provides an accurate measure of submicron aerosol concentration as long as the number distribution is not dominated by sub-0.02 micron diameter aerosol. The response of the UMCNC is compared with that of other stratospheric condensation nucleus counters, and the results of a (near) comparison with a balloon-borne condensation nucleus counter are presented. The UMCNC has operated 14 times on a NASA U-2 aircraft at altitudes from 8 to 21.5 km.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Journal of Geophysical Research (ISSN 0148-0227); 88; Aug. 20
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  • 25
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    Gas flow through rotameters (1983)
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    Publication Date: 2011-08-18
    Description: Using data available for small rotameters that use spherical floats in gas flow, a linear relationship is derived. It is noted that the relationship provides a good fit for variable volumetric flow, density, and viscosity at constant flow height. With low Reynolds numbers (Re being less than 1), the product of the variable volumetric flow and the viscosity becomes constant; at high Reynolds numbers (Re being greater than 2000), the product of the variable volumetric flow and the square root of the density becomes constant. It is pointed out that the equation given here can be used to obtain an indirect calibration with any gas of known density and viscosity. The constancy of the product of the variable volumetric flow and viscosity at low variable volumetric flows is seen as suggesting the development of simple, inexpensive gas viscometers using rotameter technology.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: I & EC-Industrial and Engineering Chemistry, Fundamentals (ISSN 0196-4313); 22; 2, 19; 1983
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  • 26
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    The Airborne Laser Ranging System - Its capabilities and applications (1983)
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    Publication Date: 2011-08-18
    Description: The Airborne Laser Ranging System is a proposed multibeam short pulse laser ranging system on board an aircraft. It simultaneously measures the distances between the aircraft and six laser retroreflectors (targets) deployed on the earth's surface. Depending on the host aircraft and terrain characteristics, the system can interrogate hundreds of targets distributed over an area as large as 60,000 sq. km in a matter of hours. Potentially, a total of 1.3 million individual range measurements can be made in a 6 hr flight. The precision of these range measurements is approximately 1 cm. These measurements are then used in a procedure which is basically an extension of trilateration techniques to derive the intersite vector between the laser ground targets. By repeating the estimation of the intersite vector, strain and strain rate errors can be estimated. These quantities are essential for crustal dynamic studies which include determination and monitoring of regional strain in the vicinity of active fault zones, land subsidence, and edifice building preceding volcanic eruptions.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Bulletin Geodesique (ISSN 0007-4632); 57; 2, 19; 1983
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  • 27
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    Moire deflectometry with deferred analysis (1983)
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    Publication Date: 2011-08-18
    Description: A simplified version of moire deflectometry for flow visualization is presented. The modification comprises replacement of the second grating, the ground glass screen, and the camera with a plate film holder to obtain a shadow picture. Postanalysis proceeds by placing a grid transparency of the same periodicity of the remaining glass grating on the negative for projection viewing. The rotational angle between the grating and the plate alters the moire fringe periodicity. Use of the method in studying flows is predicted to reveal weak density gradient areas and shocks.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics; 22; Mar. 1
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  • 28
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    Lidar system analysis for measurement of atmospheric species (1983)
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    Publication Date: 2011-08-18
    Description: Several important aspects of lidar are discussed, which pertain to a system analysis of the applicability of certain types of lidar to specific measurement objectives. The differential absorption lidar (DIAL) technique is emphasized. A brief treatment of the DIAL technique is followed by a discussion of the comparison of DIAL with other lidar measurement techniques. Sensitivity expressions are presented for DIAL with either direct or coherent (heterodyne) detection systems. A treatment of the fundamental similarities and differences in using the UV and IR spectral regions for species measurements, such as backscattering properties, spectral characteristics of the absorbing species, and factors relevant to the optimization of the DIAL measurement accuracy, is also included. Finally, results obtained from an existing ground-based DIAL system used to measure water vapor profiles are briefly discussed.
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  • 29
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    IR detectors - Heterodyne and direct (1983)
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    Publication Date: 2011-08-18
    Description: Recent developments in the area of wide-bandwidth infrared detectors, both for direct and heterodyne detection, are reviewed with emphasis on the differences and tradeoffs between photodiodes and photoconductors. In the direct-detection mode, where amplifier noise is an important consideration, the state-of-the-art detection noise equivalent power is approximated by 500 (B/10 MHz) pW. At short wavelengths (less than 1.7 micron), avalanche photodiodes offer superior performance, with a detection noise equivalent power of about 50 (B/10 MHz) pW. In heterodyne operation, near-ideal sensitivities of about 0.3 (B/10 MHz) pW have been achieved with 77K photodiodes. At 10 microns, HgCdTe photoconductors offer very good heterodyne performance at elevated temperatures: 2 (B/10 MHz) pW at 195 K and potentially 3 (B/10 MHz) pW at 250 K.
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    The time-space relationships among data points from multispectral spatial scanners (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Multispectral scanner and thematic mapper (TM) data from Landsat satellites are discussed in terms of the perceived 'simultaineity' of the images, which are obtained by scanning techniques. Scanning the scenes ensures that the data points of the images are actually sequential, even if the scan is performed at rates that are fast relative to the motion of the spacecraft. The last datum gathered by the MSS is, in fact, taken 29 sec after the first, witih a 56 m distance being present between pixels. The spacing in uneven from band to band on the TM and analyses of the data to produce an image requires consideration of nonfixed time relationships for different locations on the scan within and among the bands. Additionally, corrective measures must be taken to compensate for instrument jitter and attitude changes.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: International Journal of Remote Sensing (ISSN 0143-1161); 4; July-Sep
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    X-ray imaging of extended objects using nonoverlapping redundant array (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A common problem associated with X-ray imaging using coded apertures is the reconstruction of low-intensity extended objects. In the decoding of such objects, the overlapping images from the multiple pinholes give rise to noise cross talk and, in many cases, also to signal cross talk. In this paper, an alternate approach is proposed based on the principle used in an earlier (Yin et al., 1980) laboratory device for the real-time viewing of X-ray objects. It is shown that with this approach, the nonoverlapping redundant array, the sidelobes in the point spread function are not eliminated but merely displaced through a suitable choice of geometry. In this manner, the sidelobes no longer contribute to the background in the vicinity of a reconstructed image, and both signal and noise cross talks are completely eliminated. It may now be possible to reconstruct extended X-ray objects in 3-D by simple optical correlation and tomographically by a computer.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics (ISSN 0003-6935); 22; July 15
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    Supersonic-nitrogen flow-field measurements with the resonant Doppler velocimeter (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The application of the resonant Doppler velocimeter (RDV) for obtaining the mean velocity, temperature, and pressure measurements and flow-field visualization in a supersonic free nitrogen jet is reported. This method utilizes laser-induced fluorescence to determine the spectral absorption of an atomic or molecular species seeded into the flow. A narrow linewidth tunable laser is directed into the flow and the total fluorescence from any point is obtained as the laser is tuned. The velocity of the flow is obtained from the Doppler shifted absorption frequency, and the temperature and pressure of the gas are determined from line broadening measurements. Results are presented for the use of this technique to determine the velocity, temperature, and pressure of the flow of sodium atoms seeded into a supersonic nitrogen jet. It is concluded that the visible signal is sufficiently intense for spatially resolved flow visualization purposes.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Physics Letters (ISSN 0003-6951); 43; July 15
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  • 33
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    Seven-hole cone probes for high angle flow measurement Theory and calibration (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Previously cited in issue 08, p. 1219, Accession no. A82-22070
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: (ISSN 0001-1452)
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    A small, battery-operated fluoroscopic system - Lixiscope with X-ray generator (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A small, battery-operated X-ray generator has been developed to be used as part of a small-format fluoroscopic system, the Lixiscope (Low Intensity X-ray Imaging Scope). The X-ray generator consists of a grounded rod-anode X-ray tube with a 0.2 mm focal spot and a specially designed, battery-operated, 0 to -80 kV high-voltge supply. Total power consumption is about 10 W. The fine focal spot, in conjunction with the continuously variable X-ray intensity and spectral distribution, helps to extend both the versatility and the performance of the Lixiscope toward a much wider range of terrestrial and spacecraft applications. The complete fluoroscopic system is described, and some examples of possible applications are shown.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Materials Evaluation (ISSN 0025-5327); 41; June 198
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  • 35
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    Analysis method for Fourier transform spectroscopy (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A fast Fourier transform technique is given for the simulation of those distortion effects in the instrument line shape of the interferometric spectrum that are due to errors in the measured interferogram. The technique is applied to analyses of atmospheric absorption spectra and laboratory spectra. It is shown that the nonlinear least squares method can retrieve the correct information from the distorted spectrum. Analyses of HF absorption spectra obtained in a laboratory and solar CO absorption spectra gathered by a balloon-borne interferometer indicate that the retrieved amount of absorbing gas is less than the correct value in most cases, if the interferogram distortion effects are not included in the analysis.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics; 22; Mar. 15
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    Laboratory Automation of a Quadrupole Mass Spectrometer (1983)
    In:  CASI
    Details
    Publication Date: 2014-09-11
    Description: Efforts directed toward interfacing an LSI II bus of a PDP 11/23 desktop computer with a quadrupole mass spectrometer for the purpose of providing a convenient system whereby mass spectral data, of the products of thermal decomposition, may be rapidly acquired and processed under programmed conditions are described. The versatility and operations of the quadrupole mass spectrometer are discussed as well as the procedure for configurating the LSI II bus of the PDP 11/23 desktop computer for interfacing with the quadrupole mass spectrometer system. Data from the mass filter and other units of the spectrometer are digitally transferred to the computer whereupon mass spectral data and related data are generated.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Alabama Univ. Res. Rept.: 1983 NASA(ASEE Summer Faculty Fellowship Program; 26 p
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  • 37
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    Simultaneous multiple-point velocity measurements using laser-induced iodine fluorescence (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A technique is demonstrated for measuring velocity at multiple locations in a plane of a gaseous flowfield using Doppler-shifted absorption with fluorescence detection from iodine molecules, excited by a sheet of tunable single-axial-mode argon-ion laser radiation at 514.5 nm. Measurements were made simultaneously at 10,000 points in an iodine-seeded supersonic flow field with a 100 x 100 element photodiode array camera and were found to agree well with a numerical solution for the velocity field. The accuracy with which a component of velocity can be measured is limited, in the current approach, by the iodine linewidth to about 5 m/sec.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Optics Letters; 8; Jan. 198
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  • 38
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    Laboratory analysis of techniques for remote sensing of estuarine parameters using laser excitation (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The theoretical concepts underlying remote sensing of estuarine parameters using laser excitation are examined. The concepts are extended to include Mie scattering as a measure of the total suspended solids and to develop the water Raman signal as an internal standard. Experimental validation of the theory was performed using backscattered laser light from a laboratory tank to simulate a remote-sensing geometry. Artificially prepared sediments and biological cultures were employed to check specific aspects of the theory under controlled conditions. Natural samples gathered from a variety of water types were also analyzed in the tank to further enhance the simulation. The results indicate that it should be possible to remotely quantify total suspended solids, dissolved organics, attenuation coefficient, chlorophyll a, and phycoerythrin in estuarine water using laser excitation.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics; 22; Jan. 1
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  • 39
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    Multiwavelength analyzer for the determination of diffusion lengths (1983)
    In:  Other Sources
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    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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  • 40
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    Remote sensing of OH in the atmosphere using the technique of laser-induced fluorescence (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The use of a laser-induced fluorescence technique for the sensitive measurement of the atmospheric hydroxyl radical is discussed. Results of laboratory studies of the fluorescence and other spectroscopic properties of OH which allow the calculation of OH concentrations from the returned signals for various altitudes, water vapor contents and temperatures are presented. The experimental setup used for airborne OH measurements is then described, with particular attention given to the use of a telescope for excitation and light collection in a coaxial configuration and the periodic tuning of the exciting radiation necessary to obtain an OH signal in the presence of strong solar and nonresonant fluorescence backgrounds. The best detection limit obtained to date with the system is noted to be about 700,000 OH/cu cm, and it is expected that, with planned improvements in detection and tuning schemes, limits in the neighborhood of 1,000,000 OH/cu cm will be achieved routinely.
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  • 41
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    Coherent anti-Stokes Raman spectroscopic modeling for combustion diagnostics (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The status of modelling the coherent anti-Stokes Raman spectroscopy (CARS) spectra of molecules important in combustion, such as N2, H2O, and CO2, is reviewed. It is shown that accurate modelling generally requires highly precise knowledge of line positions and reasonable estimates of Raman linewidths, and the sources of these data are discussed. CARS technique and theory is reviewed, and the status of modelling the phenomenon of collisional narrowing at pressures well above atmospheric for N2, H2O, and CO2 is described. It is shown that good agreement with experiment can be achieved using either the Gordon rotational diffusion model or phenomenological models for inelastic energy transfer rates.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Optical Engineering (ISSN 0091-3286); 22; May-June
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  • 42
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    X-ray spectrograph design (1983)
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    Publication Date: 2011-08-18
    Description: An aberration theory is applied to spectrograph design. The initial system considered has a toroidal mirror in front of a concave grating spectrograph, giving spatial resolution perpendicular to the dispersion direction. The accuracy of the theory is shown by comparison of spot diagrams obtained from the aberrations with those produced by raytracing. The major aberrations affecting the vignetting at the intermediate slit and the spatial resolution are identified. A new system, using a holographic grating to give a flat focal plane, is then designed and optimized. It has increased spatial resolution over the wavelength range and is particularly suitable for microchannel array detectors.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics (ISSN 0003-6935); 22; May 15
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  • 43
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    Electron-photon coincidence technique for the absolute calibration of VUV detectors (1983)
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    Publication Date: 2011-08-18
    Description: A method is described whereby VUV photon detectors can be accurately calibrated. This method is illustrated by taking the 58.4-nm transition of He as an example. The technique consists of crossing a monoenergetic electron beam with a beam of He atoms. When inelastically scattered electrons which have excited the 2 1P state are detected in coincidence with the 58.4-nm photons emitted in the decay of the excited state, the interaction volume formed by the crossed beams constitutes a standard source of photons. By comparing the number of detected coincidences with the predicted number the calibration can be made. A total detector efficiency of 0.024 + or - 0.003 is obtained for a Galileo 4830 channeltron.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics (ISSN 0003-6935); 22; May 15
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    dc discharge cell for laser optogalvanic spectroscopy (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A dc electrical discharge cell for laser optogalvanic spectroscopy has been designed and tested. Signal optimization is achieved through the use of adjustable electrode positions and an orthogonal geometry between the probe laser and the discharge axis. Results are presented for visible dye laser and infrared diode laser studies of selected neutral, radical, and ion species.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Review of Scientific Instruments (ISSN 0034-6748); 54; 1454-145
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  • 45
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    Submillimeter-wave receivers - A status report (1983)
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    Publication Date: 2011-08-18
    Description: A development status assessment is presented for the work of U.S. and Western European research groups on heterodyne sub-mm receivers in the 300-1000 GHz frequency range. The applications driving sub-mm receiver and local oscillator source technologies are radio astronomy, atmospheric measurements, plasma diagnostics, and laboratory spectroscopy. Progress is concentrated in two areas, cooled Schottky diode mixers and solid state local oscillators employing frequency multipliers.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: IEEE Transactions on Microwave Theory and Techniques (ISSN 0018-9480); MTT-31; 873-878
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    Frequency standards for VLBI, present and future (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: During the last several years, J.P.L. has evaluated a number of different types of frequency standards. These evaluations include measurement of environmetal susceptibilities (barometric pressure, humidity, temperature and magnetic field) and evaluation of stability. Data from these tests are presented for quartz oscillators, rubidium vapor standards, cesium beam standards, hydrogen masers (active and passive) and a superconducting cavity stabilized oscillator. Data on reliability and mechanical ruggedness based on actual field use is also presented. A survey of new frequency standards, their likely performance and environmental characteristics is presented.
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    Ozone profile intercomparison based on simultaneous observations between 20 and 40 km (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The vertical distribution of stratospheric ozone has been simultaneously measured by means of five different instruments carried on the same balloon payload. The launches were performed from Gap during the intercomparison campaign conducted in June 1981 in southern France. Data obtained between altitudes of 20 and 40 km are compared and discussed. Vertical profiles deduced from Electrochemical Concentration Cell sondes launched from the same location by small balloons and from short Umkehr measurements made at Mt Chiran (France) are also included in this comparison. Systematic differences of the order of 20 percent between ozone profiles deduced from solar u.v. absorption and in situ techniques are found.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Planetary and Space Science (ISSN 0032-0633); 31; July 198
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  • 48
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    Single-pulse gas thermometry at low temperatures using two-photon laser-induced fluorescence in NO-N2 mixtures (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A technique suitable for measuring fluctuating temperatures in supersonic turbulent flows of N2 seeded with NO has been demonstrated in a nonflowing cell. The method relies on the two photon excitation of two selected ro-vibronic transitions in the NO gamma (alpha 2 sigma+, v prime = 0 yields ch1zp1, v double prime = 0). Previously announced in STAR as N83-20079
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Optics Letters (ISSN 0146-9592); 8; July 198
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    Acoustic ground impedance meter (1983)
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    Publication Date: 2011-08-18
    Description: A compact, portable instrument was developed to measure the acoustic impedance of the ground, or other surfaces, by direct pressure-volume velocity measurement. A Helmholtz resonator, constructed of heavy-walled stainless steel but open at the bottom, is positioned over the surface having the unknown impedance. The sound source, a cam-driven piston of known stroke and thus known volume velocity, is located in the neck of the resonator. The cam speed is a variable up to a maximum 3600 rpm. The sound pressure at the test surface is measured by means of a microphone flush-mounted in the wall of the chamber. An optical monitor of the piston displacement permits measurement of the phase angle between the volume velocity and the sound pressure, from which the real and imaginary parts of the impedance can be evaluated. Measurements using a 5-lobed cam can be made up to 300 Hz. Detailed design criteria and results on a soil sample are presented. Previously announced in STAR as N82-17476
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Acoustical Society of America, Journal (ISSN 0001-4966); 73; June 198
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    Laboratory simulation of tunable diode laser remote measurement of atmospheric gases using topographic targets (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: In order to test the possibility that tunable diode laser (TDL) systems using topographic targets can be applied to the measurement of a variety of gases at concentrations and distances characteristic of industrial gas leaks, a single-ended TDL system was assembled for use with selected topographic targets to detect NO2 at atmospheric pressure and NO2 and NH3 at low pressures. In both cases, the intensity distribution of radiation backscattered from selected targets was found to be heavily weighted to a specular rather than a Lambertian distribution. A sensitivity of 5 ppm-m has been demonstrated for the case of NO2.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics (ISSN 0003-6935); 22; July 1
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    Comment on 'Can the standard radiosonde system meet special atmospheric research needs?' (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Geophysical Research Letters (ISSN 0094-8276); 10; June 198
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  • 52
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    Aberrations of holographic toroidal grating systems (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Expressions are derived for the sixteen wave front aberration coefficients of a single grating. These give the wave aberrations to the fourth order for a plane symmetric grating system. The contributions from each mirror and grating can be added to give the aberrations in the final image. Problems encountered with intermediate astigmatic images are overcome by defining the wave front aberration with respect to an astigmatic reference surface. There is one field variable describing displacement of the object point from the symmetry plane. The aperture stop may be placed anywhere in the system, and equations are given for the aberration changes produced by sifting this position.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics (ISSN 0003-6935); 22; May 15
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    Airflow resistivity instrument for in situ measurement on the earth's ground surface (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: An airflow resistivity instrument features a novel specimen holder, especially designed for in situ measurement on the earth's ground surface. This capability eliminates the disadvantages of prior intrusive instruments, which necessitate the removal of a test specimen from the ground. A prototype instrument can measure airflow resistivities in the range 10-5000 cgs rayl/cm, at specimen depths up to 15.24 cm (6 in.), and at differential pressures up to 2490.8 dyn sq cm (1 in. H2O) across the specimen. Because of the close relationship between flow resistivity and acoustic impedance, this instrument should prove useful in acoustical studies of the earth's ground surface. Results of airflow resistivity measurements on an uncultivated grass field for varying values of moisture content are presented.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Review of Scientific Instruments (ISSN 0034-6748); 54; May 1983
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    A survey of laser and selected optical systems for remote measurement of pollutant gas concentrations (1983)
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    Publication Date: 2011-08-18
    Description: Applications of the Differential Absorption Lidar (DIAL) technique to the remote sensing of pollutant gases are surveyed. In the DIAl technique, the differential absorption of two laser beams reflected back to a receiver from a target determines the concentration of the gas being studied. The types of instruments available are considered in detail: dye lidar (to measure nitrogen dioxide, sulfur dioxide, and ozone); carbon dioxide laser (for ozone, ethylene, ammonia, and hydrazine), helium-neon laser (for methane); hydrogen fluoride laser (for HF); and tunable diode laser (for nitric oxide and carbon monoxide). DIAL instruments are compared with other optical remote sensors such as Fourier-transform infrared spectrometers, correlation spectrometers (COSPEC and GASPEC), and grating spectrometers; and criteria for the selection of an appropriate gas measuring system are suggested. Laser and other optical remote sensors are found to be cost effective in many cases, despite the fact that they are more costly than point-monitoring systems.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Air Pollution Control Association, Journal (ISSN 0002-2470); 33; March 19
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    Field investigation of techniques for remote laser sensing of oceanographic parameters (1983)
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    Publication Date: 2011-08-18
    Description: A laser fluorosensor, previously studied in the laboratory, was deployed at a pier in lower Chesapeake Bay for field testing. A Q-switched Nd:YAG laser doubled to 532 nm in conjunction with a gated optical multichannel analyzer (OMA) allow spectra with high signal-to-noise ratios to be recorded in full daylight at a distance of 20 m. As a test of the system a study was conducted of the spatial and temporal variations of the phytopigments phycoerythrin and chlorophyll. The phycoerythrin feature was resolved into two components, one attributable to cyanophytes and the other to cryptophytes. A comparison was also made with spectra obtained by the NASA airborne oceanographic lidar (AOL).
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Remote Sensing of Environment; 13; Mar. 198
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    Nuclear Science Symposium, 29th, and Symposium on Nuclear Power, 14th, Washington, DC, October 20-22, 1982, Proceedings (1983)
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    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.
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    New method of determining the onset of ring cracking (1983)
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    Publication Date: 2011-08-18
    Description: A technique is developed for the detection of the onset of circumferential ring cracks in a flat brittle piece of an electrically insulating material. Thin metal films were deposited on both the insulating indentor (diamond) and the insulating brittle flat. The initiation of a ring crack was signified by a step in the monitored electrical contact resistance between the indentor and flat metal films versus the applied force. It was determined by tests performed on polished glass slides using diamond indentors that this technique is both sensitive and reproducible. The onset of crack formation as observed by optical means was found to occur at the same time as the step in the contact resistance when both experiments were carried out simultaneously.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Review of Scientific Instruments; 54; Mar. 198
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    NASA multipurpose airborne DIAL system and measurements of ozone and aerosol profiles (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The hardware, operational characteristics, data processing system, and applications of the NASA airborne differential absorption lidar (DIAL) system are described. DIAL functions by assessing the average gas concentration over a specified range interval by analyzing the difference in lidar backscatter signals for laser wavelengths tuned on and off of the molecular absorption line of a gas under investigation. The system comprises two frequency-doubled Nd:YAG lasers pumping two high conversion efficiency tunable dye lasers emitting pulses separated by 100 microsec or less. The return signals are digitized and stored on magnetic tape. The signal collector consists of photomultiplier tubes implanted in a cassegrain telescope. Flight tests of the system involved on-measurements at 285.95 nm and off-measurements at 299.40 nm, which yielded a differential cross section of 1.74 x 10 to the -16th sq cm. In situ measurements with another plane at a nominal altitude of 3.2 km for comparison purposes showed accuracy to within 10% in and above the boundary layer. The system is considered as a test apparatus for more developed versions to be flown on the Shuttle
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics; 22; Feb. 15
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    Techniques for the correction of topographical effects in scanning Auger electron microscopy (1983)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: A number of ratioing methods for correcting Auger images and linescans for topographical contrast are tested using anisotropically etched silicon substrates covered with Au or Ag. Thirteen well-defined angles of incidence are present on each polyhedron produced on the Si by this etching. If N1 electrons are counted at the energy of an Auger peak and N2 are counted in the background above the peak, then N1, N1 - N2, (N1 - N2)/(N1 + N2) are measured and compared as methods of eliminating topographical contrast. The latter method gives the best compensation but can be further improved by using a measurement of the sample absorption current. Various other improvements are discussed.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Journal of Applied Physics; 54; Jan. 198
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    A hot-wire method for high-intensity turbulent flows (1983)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: A measuring technique for determing instantaneous, three-dimensional velocity vectors in highly turbulent flows by means of a 4-sensor hot-wire probe is described. As is well known, the hot-wire signal received in reversing flows cannot uniquely be interpreted. This difficulty is circumvented by tracking the thermal wake of a heated wire. Whenever the approximate flow direction is indicated by a temperature-sensitive wake detector, all components of the instantaneous velocity vector are evaluated by means of a digital data reduction method. Uniqueness of the solution derived from the triple-hot-wire response equations is examined. A first application of the proposed measuring technique in the recirculating flow downstream of a backward-facing step is described.
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    Synthetic aperture radar imaging using acousto-optics and charge-coupled devices (1983)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: The operating principles of an acoustooptic/CCD real-time SAR processor are described, and experimental results are presented. Particular consideration is given to time-and-space integrating processing, the range processor, and the azimuth processor. The interferometric detection scheme is examined in detail.
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    Time-of-flight anemometer for hot section applications (1983)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The design, construction and testing of laser anemometer configurations for Hot Section velocity measurements is considered. Optimizing the laser anemometer system necessarily included the data processing algorithms used. It is felt that the requirements here are too demanding for standard laser anemometer systems.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Lewis Research Center Turbine Eng. Hot Sect. Technol. (HOST); p 69-71
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    Hot section viewing system (1983)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The objective of the hot section viewing program is to develop a prototype optical system for viewing the interior of a gas turbine combustor during high temperature, high pressure operation in order to produce a visual record of some causes of premature hot section failures. The program began by identifying and analyzing system designs that would provide clearest images while being able to survive the hostile environment inside the combustion chamber. Different illumination methods and computer techniques for image enhancement and analysis were examined during a preliminary test phase. In the final phase of the program the prototype system was designed and fabricated and is currently being tested on a high pressure combustor rig.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Lewis Research Center Turbine Eng. Hot Sect. Technol. (HOST); p 11-16
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    HOST instrumentation R and D program overview (1983)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The HOST Instrumentation R&D program is focused on two categories of instrumentation. One category is that required to characterize the environment imposed on the hot section components of turbine engines. This category includes instruments for measuring gas flow, gas temperature, and heat flux. The second category is that for measuring the effect of the environment on the hot section components. This category includes strain measuring instruments and an optical system for viewing the interior of an operating combustor to detect cracks, buckling, carbon buildup, etc.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Turbine Eng. Hot Sect. Technol. (HOST); p 7-9
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    Development of heat flux sensors for turbine airfoils and combustor liners (1983)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The design of durable turbine airfoils that use a minimum amount of cooling air requires knowledge of the heat loads on the airfoils during engine operation. Measurement of these heat loads will permit the verification or modification of the analytical models used in the design process and will improve the ability to predict and confirm the thermal performance of turbine airfoil designs. Heat flux sensors for turbine blades and vanes must be compatible with the cast nickel-base and cobalt-base materials used in their fabrication and will need to operate in a hostile environment with regard to temperature, pressure and thermal cycling. There is also a need to miniaturize the sensors to obtain measurements without perturbing the heat flows that are to be measured.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Lewis Research Center Turbine Eng. Hot Sect. Technol. (HOST); p 45-55
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    Design and performance of the Stratospheric Aerosol and Gas Experiment II (SAGE II) instrument (1983)
    In:  Other Sources
    Details
    Publication Date: 2018-12-01
    Description: Design and performance data are analyzed for the Stratospheric Aerosol and Gas Experiment II (SAGE II) instrument, which has been developed for the NASA Earth Radiation Budget Satellite (ERBS). SAGE II is designed to monitor globally, from 70 degrees S to 70 degrees N latitude, the vertical distribution of stratospheric aerosols, ozone, water vapor, and nitrogen dioxide by measuring the extinction of solar radiation through the earth's atmosphere during the ERBS observatory solar occultations. A flat scanning mirror reflects solar radiation into a Cassegrain type telescope, which forms a solar image on the entrance slit of a grating spectrometer. The instantaneous-field-of-view of the SAGE II is scanned along the vertical solar diameter by the elevation scan mirror. The optical system is contained within an azimuth gimbal which tracks the solar radiometric centroid during the data event, while the spectrometer isolates seven spectral wavelengths from 0.385-1.02 micrometers. The seven channels of the spectrometer use silicon photodiode dedectors operated in the photovoltaic mode. The detector outputs are multiplexed into a serial data stream for readout by the ERBS telemetry system, with each output being sampled 64 times per second and digitized to 12 bit resolution.
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    Information theory analysis of sensor-array imaging systems for computer vision (1983)
    In:  Other Sources
    Details
    Publication Date: 2018-12-01
    Description: Information theory is used to assess the performance of sensor-array imaging systems, with emphasis on the performance obtained with image-plane signal processing. By electronically controlling the spatial response of the imaging system, as suggested by the mechanism of human vision, it is possible to trade-off edge enhancement for sensitivity, increase dynamic range, and reduce data transmission. Computational results show that: signal information density varies little with large variations in the statistical properties of random radiance fields; most information (generally about 85 to 95 percent) is contained in the signal intensity transitions rather than levels; and performance is optimized when the OTF of the imaging system is nearly limited to the sampling passband to minimize aliasing at the cost of blurring, and the SNR is very high to permit the retrieval of small spatial detail from the extensively blurred signal. Shading the lens aperture transmittance to increase depth of field and using a regular hexagonal sensor-array instead of square lattice to decrease sensitivity to edge orientation also improves the signal information density up to about 30 percent at high SNRs.
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    Theoretical performance of a vortex generator type of cloud droplet sampler (1983)
    In:  Other Sources
    Details
    Publication Date: 2018-12-01
    Description: One of the goals of the NASA global tropospheric research program is understanding the chemical processes which influence the chemistry of the natural troposphere. An important element of this program is the study of the role of heterogenous chemistry in global tropospheric chemical cycles. Any study of the part which clouds play in the chemistry of tropospheric trace constituents requires a determination of cloud water chemical composition. There exists, therefore, a need for highly efficient collector devices which can obtain unbiased samples of cloud water in sufficient quantities aboard an aircraft platform. A promising concept which could meet the dual requirements of accurate sampling and efficient collection of cloud water droplets in the vortex generator. This concept involves an inertial separator which uses the centrifugal force of a rotating airstream. The separator is built into a commercial device which has been used for many years as a dust separator for air breathing engines. Attention is given to the optimization of the sampler design.
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  • 69
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    Application of laser anemometry in turbine engine research (1983)
    In:  Other Sources
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    Publication Date: 2018-12-01
    Description: The application of laser anemometry to the study of flow fields in turbine engine components is reviewed. Included are discussions of optical configurations, seeding requirements, electronic signal processing, and data processing. Some typical results are presented along with a discussion of ongoing work.
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    Developing mass spectrometric techniques for boundary layer measurement in hypersonic high enthalpy test facilities (1983)
    In:  Other Sources
    Details
    Publication Date: 2018-12-01
    Description: Thermodynamic flow properties of gases in the boundary layer or the flowfield have been mainly deduced from pressures and temperatures measured on a model. However, further progress with respect to an understanding of these properties requires a more complete characterization of the layer including determination of the gas composition and chemistry. Most attempts to measure boundary layer chemistry involve the employment of a mass spectrometer and an associated gas sampling system. The three major limiting factors which must be addressed for species measurement in aerothermodynamic investigations on models at reentry stream velocities, are gas sampling effects, instrument limitations, and problems with data acquisition. The present investigation is concerned with a concentrated effort to quantitatively identify and correct for instrument and sampling system effects, and to develop a miniaturized high performance mass spectrometer for on-model real-time analysis of the boundary layer and its associated atmosphere.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
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    Dynamic gas temperature measurement system. Volume 2: Operation and program manual (1983)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The hot section technology (HOST) dynamic gas temperature measurement system computer program acquires data from two type B thermocouples of different diameters. The analysis method determines the in situ value of an aerodynamic parameter T, containing the heat transfer coefficient from the transfer function of the two thermocouples. This aerodynamic parameter is used to compute a fequency response spectrum and compensate the dynamic portion of the signal of the smaller thermocouple. The calculations for the aerodynamic parameter and the data compensation technique are discussed. Compensated data are presented in either the time or frequency domain, time domain data as dynamic temperature vs time, or frequency domain data.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA-CR-168267-VOL-2 , NAS 1.26:168267-VOL-2
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    Techniques for Analysis of DSN 64-meter Antenna Azimuth Bearing Film Height Records (1983)
    In:  CASI
    Details
    Publication Date: 2014-09-10
    Description: The DSN 64-m antennas use oil pad azimuth thrust bearings. Instrumentation on the bearing pads measures the height of the oil film between the pad and the bearing runner. Techniques to analyze the film height record are developed and discussed. The analysis techniques present the unwieldy data in a compact form for assessment of bearing condition. The techniques are illustrated by analysis of a small sample of film height records from each of the three 64-m antennas. The results show the general condition of the bearings of DSS 43 and DSS 63 as good to excellent, and a DSS 14 as marginal.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: The Telecommun. and Data Acquisition Rept.; p 92-118
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    Intercontinental time and frequency transfer using a global positioning system timing receiver (1983)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The DSN has a requirement to maintain knowledge of the frequency offset between DSN stations with 3 x 10 to the minus 13th power and time offset within 10 microseconds. It is further anticipated that in the 1987-1990 era the requirement for knowledge of time offset between DSN stations will be less than 10 nanoseconds. JPL is using the Global Positioning System (GPS) Space Vehicles, as a development project, to transfer time and frequency over intercontinental distances between stations of the DSN and between the DSN and other agencies. JPL has installed GPS timing receivers at its tracking station near Barstow, California, and at its tracking station near Madrid, Spain. The details of the experiment and the data are reported. There is a discussion of the ultimate capabilities of these techniques for meeting the functional requirements of the DSN.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: The Telecommun. and Data Acquisition Rept.; p 98-104
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  • 74
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    Cesium standard for satellite application (1983)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: A Cesium frequency standard that was developed for satellite applications is discussed. It weighs 23 lbs. and uses 23.5 watts of power, achieves a stability of 1 x ten to the minus 13th power/100,000 seconds, and is radiation hardened. To achieve the weight and reliability requirements, both thick and thin film hybrid circuits were utilized. A crystal oscillator is used to improve short-term stability and performance on a moving platform.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Goddard Space Flight Center Proc. of the 14th Ann. Precise Time and Time Interval (PTTI) Appl. Planning Meeting; p 315-322
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  • 75
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    Stochastic models for atomic clocks (1983)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: For the atomic clocks used in the National Bureau of Standards Time Scales, an adequate model is the superposition of white FM, random walk FM, and linear frequency drift for times longer than about one minute. The model was tested on several clocks using maximum likelihood techniques for parameter estimation and the residuals were acceptably random. Conventional diagnostics indicate that additional model elements contribute no significant improvement to the model even at the expense of the added model complexity.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Goddard Space Flight Center Proc. of the 14th Ann. Precise Time and Time Interval (PTTI) Appl. Planning Meeting; p 295-306
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    A new calibration method for time delay standard and its application (1983)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: A method which is used to measure time delay accurately by using a Type 900-LB slotted line is described. The accuracy for calibrating time delay of a precision coaxial air line Type 900-L is about + or - (0.4 to 0.6)ps, and for coaxial cables with VSWR less than 1.5 and time delay t less than 50ns is about + or - (3 to 5)ps. Theoretical analysis and mathematical derivation of microwave networks in cascade are given. Methods to eliminate the errors which are caused by the discontinuities and the error analysis of the measuring system are presented. Skin effect analysis of the transient characteristic of coaxial transmission line are discussed in detail. Methods to eliminate the errors which result from using the calibrated time delay standard to calibrate time interval measurement instruments are presented. The estimation of errors and formulae for correction of those errors are described.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Goddard Space Flight Center Proc. of the 14th Ann. Precise Time and Time Interval (PTTI) Appl. Planning Meeting; p 155-180
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  • 77
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    A rubidium clock for SEEK-TALK (1983)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The development of a tactical rubidium frequency standard (TRFS) for the SEEK-TALK program is discussed. This effort, which is entering the prototype stage, is directed toward the establishment of a production capability for miniature rubidium clocks of medium stability capable of fast warmup and extreme ruggedness for military avionics applications. The overall unit consists of an ultraminiature physics package and four plug-in circuit boards inside a 2 1/2-inch square by 4-inch box. This size is achieved without the extensive use of hybrid microcircuitry, yet is believed to be the smallest atomic frequency standard yet developed.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Goddard Space Flight Center Proc. of the 14th Ann. Precise Time and Time Interval (PTTI) Appl. Planning Meeting; p 141-154
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    Time maintenance of user clocks via the tracking and data relay satellite system (1983)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: A system is described which uses the Tracking and Data Relay Satellite System (TDRSS) itself to compare the user satellite clock with a clock at the White Sands station that is referenced to Universal Time Coordinated (UTC). No command of the spacecraft by the system is required, and actual on-board clock corrections are made by the spacecraft control center at its discretion. Computer models were constructed using basic orbital parameters for user and TDRS satellites. With only first-order corrections and simple averaging techniques for constant clock rates, error measurement precision of better than one microsecond was obtained. More sophisticated computations should allow considerable improvement over this.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Goddard Space Flight Center Proc. of the 14th Ann. Precise Time and Time Interval (PTTI) Appl. Planning Meeting; p 39-56
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  • 79
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    Neutral gas mass spectrometer on the IECM (1983)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The neutral gas mass spectrometer on the Induced Environment Contamination Monitor is described. The results of the measurements are presented.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Systematics General Corp. The Shuttle Environ. Workshop; 8 p
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  • 80
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    Recent applications of a laser velocimeter in the Langley 4by 7-meter Wind Tunnel (1983)
    In:  Other Sources
    Details
    Publication Date: 2018-12-01
    Description: A long focal length laser velocimeter (LV) has become a production measurement tool in the Langley 4- by 7-Meter Tunnel. Two recent applications of the LV include flowfield measurements: (1) in the wake of a helicopter, and (2) around the wing of an aspect-ratio (AR) 7 wing-body model. A discussion of these two applications is provided along with a description of the flowfields in terms of the mean velocities and turbulence intensities.
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  • 81
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    High temperature static strain sensor development program (1983)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Electrical resistance strain gages useful for static strain measurements on nickel or cobalt superalloy parts inside a gas turbine engine on a test stand are being developed. Measurements of this type are of great importance in meeting the goals of the HOST program because, without reliable knowledge of the stresses and strains which exist in specific components, it will be difficult to fully appreciate where improvements in design and materials can be implemented. The first part of the effort consisted of a strain gage alloy development program which will be followed by an investigation of complete strain gage systems which will use the best of the alloys developed together with other system improvements.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Lewis Research Center Turbine Eng. Hot Sect. Technol. (HOST); p 37-40
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  • 82
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    Dynamic gas temperature measurement system (1983)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A gas temperature measurement system with compensated frequency response of 1 KHz and capability to operate in the exhaust of a gas turbine combustor was developed. Environmental guidelines for this measurement are presented, followed by a preliminary design of the selected measurement method. Transient thermal conduction effects were identified as important; a preliminary finite-element conduction model quantified the errors expected by neglecting conduction. A compensation method was developed to account for effects of conduction and convection. This method was verified in analog electrical simulations, and used to compensate dynamic temperature data from a laboratory combustor and a gas turbine engine. Detailed data compensations are presented. Analysis of error sources in the method were done to derive confidence levels for the compensated data.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Lewis Research Center Turbine Eng. Hot Sect. Technol. (HOST); p 17-35
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  • 83
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    A portable telescope, photometer, and data-recording system (1983)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: A description is presented of a portable telescope, two-channel photometer and high-speed data-recording system that meet the unique requirements of occultation astronomy. The instrumentation has been designed for portability, high time resolution, accurate absolute timing, and ease of use. The instrumentation includes a light-weight 35.5-cm (14-inch) objective portable telescope, a two-channel high-speed photometer and a data-recording system built into a suitcase. The equipment has been successfully used in field operations and at fixed observatories in India, Australia, and Hawaii.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Astronomical Society of the Pacific, Publications (ISSN 0004-6280); 95; 925-937
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    Optical detectors for spectroscopy (1983)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: The modes of operation of photoconductive and photoemissive array detectors are described, and their performance characteristics compared and contrasted, with emphasis on their suitability for use as detectors for optical spectroscopy. The prospects for future developments of the array detectors are discussed.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Astronomical Society of the Pacific, Publications (ISSN 0004-6280); 95; 810-834
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    Long wavelength photoconductive detectors for airborne and orbital infrared astronomy (1983)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Seven gallium doped germanium (Ge:Ga) photoconductive infrared detectors were fabricated and mounted in integrating cavities. In addition, a cold preamplifier package consisting of J230 junction field effect transistors (JFETs) was produced. Tests of the system under low photon background conditions indicated that sensitivity was limited by the Johnson noise of the load resistor. The detectors were mounted in the Ames cooled grating spectrometer, and flown on the Kuiper Airborne Observatory. Good quality astronomical data were obtained during the flight of 7 July 1983.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA-CR-166586 , NAS 1.26:166586
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    Application of image processing technology to problems in manuscript encapsulation (1983)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The long term effects of encapsulation individual sheets of the Codex Hammer were investigated. The manuscript was simulated with similar sheets of paper which were photographed under repeatable raking light conditions to enhance their surface texture, encapsulated in plexiglas, cycled in an environmental test chamber, and rephotographed at selected intervals. The film images were digitized, contrast enhanced, geometrically registered, and apodized. An FFT analysis of a control sheet and two experimental sheets indicates no micro-burnishing, but reveals that the ""mesoscale'' deformations with sizes 8mm are degrading monotonically, which is of no concern. Difference image analysis indicates that the sheets were increasingly stressed with time and that the plexiglas did not provide a sufficient environmental barrier under the simulation conditions. The relationship of these results to the Codex itself is to be determined.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA-CR-173200 , JPL-PUB-83-75 , NAS 1.26:173200
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  • 87
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    X-ray sensor development for magnetospheric research (1983)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The ARPA-301 data on the P78-1 satellite provide information on the long-term X-ray environment; specifically, the distributions in total X-ray intensities and energy spectral parameters and the spatial extents of the X-ray sources. The average X-ray intensity near noontime was found to decrease with increasing local time whereas the opposite trend occurs around midnight. At both of these local times, the average flux increases with increasing level of geomagnetic activity. The distributions in flux are also considered for given local time intervals and these span a large dynamic range. The temporal correlation between the X-ray flux in different local time sectors is found to decrease with increasing difference in local time. The average spectral shapes do not depend significantly upon local time or geomagnetic activity.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA-CR-173172 , NAS 1.26:173172 , D137
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  • 88
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    On 3He bolometer systems (1983)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A 3He cryostat which was constructed to cool a germanium bolometer for use as an infrared detector at submillimeter wavelength is discussed. The system had better sensitivity than any other existing system for these wavelengths; the system could be improved if better optical coupling could be achieved between the bolometer and the incoming photon stream. Considerable effort was expended to improve this coupling. Even the best results however, fell short of an ideal system by a factor of nearly 5 in coupling efficiency.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA-CR-175325 , NAS 1.26:175325
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  • 89
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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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  • 90
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    An assessment of flow-field simulation and measurement (1983)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: The effectiveness of the instrumentation, techniques, and wind tunnel flow characterizations in the U.S. large scale wind tunnels for accuracy in making increasingly finer drag measurements on airfoils is assessed. The more reliable measurement is necessary due to refined designs of airfoils and the need to continue to improve the economic performance of commercial aircraft. Consequently, the effects of flows in wind tunnels, compared with those in the freestream environment, have become a critical factor. Dynamic flow properties in individual wind tunnels have to be documented in order to assure reproducible results. Laser velocimetry is a suitable tool for nonintrusive measurement of the mean velocity, turbulence intensity, and the shear stress in wind tunnel flowfields. It is suggested that future wind tunnel studies be designed to remain within the diagnostic capabilities available at the site.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: AIAA PAPER 83-1721
    Format: text
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  • 91
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    Tradeoffs among several synthetic aperture radar image quality parameters - Results of a user survey study (1983)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The imagery obtained with the aid of synthetic aperture radars (SAR) has been applied to several remote sensing disciplines such as geologic feature mapping, oceanic phenomena studies, and land use and urban morphology studies. The successful SAR experiment on Seasat and the Shuttle demonstrated the feasibility of global radar mapping at relatively high resolution from a spaceborn platform. The present investigation is concerned with the requirements of and the tradeoffs among several SAR image quality parameters. The results are presented from a survey study concerning the interpretability of a set of SAR images. The data used to generate these images were obtained by the Seasat SAR experiments. Attention is given to image scenes and the simulation experiment, image interpretation survey results, multiple-looks, the number of looks vs resolution, and number of bits vs resolution.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Photogrammetric Engineering and Remote Sensing (ISSN 0099-1112); 49; June 198
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  • 92
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    An ultraviolet spectrograph using an echelle grating with cross-disperser for the measurement of stratospheric constituents (1983)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The present investigation is concerned with the development of a high resolution echelle-cross disperser grating spectrograph for application in groundbased, balloon, and Shuttle studies of the middle atmosphere and thermosphere. All the design features discussed pertain specifically to the balloon instrument. Attention is given to examples of scientific objectives for the middle atmosphere, aspects of instrument description, imaging requirements, the spectral multiplexing capability, broad wavelength coverage, sensitivity, dynamic range, scattered light, the optical configuration of the instrument, the detector system, the data system, and the results of laboratory tests and theoretical evaluations.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: AIAA PAPER 83-0020
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  • 93
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    The design of optimum remote-sensing instruments (1983)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Remote-sensing instruments allow values for certain properties of a target to be retrieved from measurements of radiation emitted, reflected or transmitted by the target. The retrieval accuracy is affected by random variations in the many target properties which affect the measurements. A method is described, by which statistical properties of the target and theoretical models of its electromagnetic behavior can be used to choose values for the instrument parameters which maximize the retrieval accuracy. The technique is applicable to a wide range of remote-sensing instruments.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: International Journal of Remote Sensing (ISSN 0143-1161); 4; Apr
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  • 94
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    Optimizing a remote sensing instrument to measure atmospheric surface pressure (1983)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Atmospheric surface pressure can be remotely sensed from a satellite by an active instrument which measures return echoes from the ocean at frequencies near the 60 GHz oxygen absorption band. The instrument is optimized by selecting its frequencies of operation, transmitter powers and antenna size through a new procedure baesd on numerical simulation which maximizes the retrieval accuracy. The predicted standard deviation error in the retrieved surface pressure is 1 mb. In addition the measurements can be used to retrieve water vapor, cloud liquid water and sea state, which is related to wind speed.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: International Journal of Remote Sensing (ISSN 0143-1161); 4; Apr
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  • 95
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    High-resolution submillimeter-wave radiometry of supersonic flow (1983)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The recent development of a high-resolution submillimeter-wave heterodyne radiometer has made possible the first measurements of H2O molecule rotational line excitation temperatures and detailed profiles in supersonic flow. Absorption signals were measured across the flow for the 2/11/ from 2//02/ (752 GHz) para-H2O rotational transition against a hot background. These signals decrease downstream owing to the volume expansion of the gas away from the sonic nozle exit in the high-vacuum chamber. Radiative transfer calculations based on the large-velocity-gradient approximation and multilevel statistical equilibrium agree with these results and with the measured spectral line shapes. The data reveal nearly isentropic gas expansion and cooling. These studies have shown that submillimeter-wave heterodyne radiometry can be useful for remote sensing of supersonic flow with low mass flux, provided the signal transmission is through a dry or thin atmosphere.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: AD-A135084 , ESD-TR-83-098 , Applied Physics Letters (ISSN 0003-6951); 42; May 15
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  • 96
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    Digital image processing of flow visualization photographs (1983)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: This paper is concerned with the propagation of laser light through a slab of a randomly varying medium. A theoretical analysis is presented which relates the spectrum of the recorded-intensity field some distance downstream of the medium to the spectrum of the index-of-refraction field. For a homogeneous and isotropic random field, the 3-D spectrum of the medium is obtained from the 2-D spectrum of the photograph by dividing each component of the spectrum by the frequency raised to the fourth power. Free-space propagation outside the random medium is accounted for by a scaling factor. Experimental results are presented which support the theoretical analysis. The nonintrusive diagnostic technique presented here is applicable to photographs which contain partially developed caustic networks.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics (ISSN 0003-6935); 22; May 15
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  • 97
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    Measurements of a supersonic velocity in a nitrogen flow using inverse Raman spectroscopy (1983)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Results are presented for supersonic molecular flow-velocity measurements using inverse Raman spectroscopy. The flow velocity, temperature, and density of flowing N2 molecules are measured because of potential wind-tunnel applications. Uncertainties of less than 5% are found for the velocity measurements, while the uncertainties are about 10% for the temperature and density measurements. The laser probe is stabilized by using I2 fluorescence, and I2 saturated absorption is utilized to provide an absolute frequency reference. Differential detection techniques are employed to reduce detection noise.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Optics Letters; 8; Apr. 198
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  • 98
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    Development and characterization analysis of a radar polarimeter (1983)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The interaction of electromagnetic waves with natural earth surface was of interest for many years. A particular area of interest in controlled remote sensing experiments is the phenomena of depolarization. The development stages of the radar system are documented. Also included are the laboratory procedures which provides some information about the specifications of the system. The radar system developed is termed the Radar Polarimeter System. A better insight of the operation of the RPS in terms of the newly developed technique--synthetic aperture radar system is provided. System performance in tems of radar cross section, in terms of power, and in terms of signal to noise ratio are also provided. In summary, an overview of the RPS in terms of its operation and design as well as how it will perform in the field is provided.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA-CR-175259 , NAS 1.26:175259
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  • 99
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    A portable x-ray analyzer for wearmetal particles in lubricants (1983)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: An extensive program exists for the systematic sampling and analysis of lubricants in U.S. Air Force aircraft engines. The sudden development of excessive engine wear can usually be detected on the basis of monitoring the concentration of several key metallic elements for each aircraft engine. In many cases even the specific fault within an engine can be recognized. The two types of equipment which are currently being employed for the conduction of oil analyses make use of atomic emission or atomic absorption spectroscopy. In both cases, heavy, large, and relatively fragile pieces of equipment are involved. Difficulties concerning the transportation of these devices have led to the development of a small, sturdy, and easily portable wearmetal analyzer. The analyzer makes use of an X-ray fluorescence technique.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
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  • 100
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    Device for determining frost depth and density (1983)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A hand held device having a forward open window portion adapted to be pushed downwardly into the frost on a surface, and a rear container portion adapted to receive the frost removed from the window area are described. A graph on a side of the container enables an observer to determine the density of the frost from certain measurements noted. The depth of the frost is noted from calibrated lines on the sides of the open window portion.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Format: application/pdf
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