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  • Other Sources  (241)
  • INSTRUMENTATION AND PHOTOGRAPHY  (241)
  • 1980-1984  (241)
  • 1925-1929
  • 1982  (241)
  • 1927
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  • 1
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    Determination of the efficiency of a proportional counter for detecting X-rays (1982)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: A parallel beam of X-rays (approximately monoenergetic) passing through a rectangular slit and scattering from two flat mirrors comprise the X-ray test. The two mirrors are arranged in a periscope geometry so that the final reflected beam is parallel to the incident beam but displaced laterally by given amount. One of the detectors used to intercept the reflected X-rays is a one dimensional gas-filled proportional counter which is sensitive to the position (in 1 dimension) at which the X-rays are incident within its detecting "window". The total length of the anode wire of the proportional counter is 120 mm and this length can be divided electronically into a maximum of 1,024 parts. Hence, the output of an experimental run would be the number of incident X-rays that registered on each of the 1,024 channels. Each channel would represent an X-ray at a different spatial location and, hence, at a different scattering angle. In order to look at a wider range of scattering angles, the detector is placed on an optical table which can be rotated.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Alabama Univ. in Huntsville The 1981 NASA(ASEE Summer Fac. Fellowship Program; 6 p
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  • 2
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    Performance of the continuous flow diffusion chambers (1982)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: A brief comparative description is made of the chambers. Overall, comparisons for the various types of experiments - monodisperse, polydisperse and ambient aerosol - showed agreement among these chambers to within 15% in most cases. A careful analysis of the results indicated that a proper accounting of certain parameters would bring about much closer agreement among four of these instruments.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: The Third Intern. Cloud Condensation Nuclei Workshop; p 79-84
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  • 3
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    Programmable temperature control system for biological materials (1982)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: A system was constructed which allows programmable temperature-time control for a 5 cu cm sample volume of arbitrary biological material. The system also measures the parameters necessary for the determination of the sample volume specific heat and thermal conductivity as a function of temperature, and provides a detailed measurement of the temperature during phase change and a means of calculating the heat of the phase change. Steady-state and dynamic temperature control is obtained by supplying heat to the sample volume through resistive elements constructed as an integral part of the sample container. For cooling purposes, this container is totally immersed into a cold heat sink. Using a mixture of dry ice and alcohol at 79 C, the sample volume can be controlled from +40 to -60 C at rates from steady state to + or - 65 C/min. Steady-state temperature precision is better than 0.2 C, while the dynamic capability depends on the temperature rate of change as well as the mass of both the sample and the container.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: IEEE Transactions on Biomedical Engineering; BME-29; Aug. 198
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  • 4
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    An instrument for measuring thermal inertia in the field (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Features and test results of a thermal inertial meter (TIM) for cataloging the thermal inertial of surface material in situ as a basis for satellite remote sensing of geologic materials are described. The instrument is employed to determine the temperature rise of the materials in the field, with the assumptions that the sample and a standard are homogeneous in composition, the heat flux density is constant at the surface of each material, and the specimens are thick enough to be treated as semi-infinite bodies. A formula for calculating thermal inertia is presented, and the components of the TIM are detailed. A box with three compartments, two holding standards, is placed on the sample surface with the third compartment open to the specimen. Dolomite and quartz are used as references when all samples are measured after heating. Tests with rocks and sand in Nevada and California revealed that chert has a higher thermal inertia than barite.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Photogrammetric Engineering and Remote Sensing; 48; Apr. 198
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  • 5
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    A PPM modulator and demodulator for the 2.5 bit/detected photon demonstration (1982)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: In addition to performing the basic pulse position modulation and demodulation, the hardware described also indicates the occurrence of erasures and errors of various types. The analyzer portion of the circuit counts the number of pulses received in a word, demodulates a second input pulse (if one is received), indicates the occurrence of erasures, and detects PPM word errors. Word errors are detected by comparing the modulator input word to the corresponding demodulator output. These functions are provided mainly for testing and diagnosis of the system during the feasibility demonstration period.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: The Telecommun. and Data Acquisition Rept.; p 50-54
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  • 6
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    Master timing system measurements (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The test results indicate that the system performs within the specifications established. The overall system appears to be well designed and built to a good commercial grade. The triple redundant time code generators, whose outputs are majority voted, performed adequately as far as could be determined on an operational situation.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: The Telecommun. and Data Acquisition Rept.; p 70-74
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  • 7
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    A comparison of turbulence intensity measurements using a laser velocimeter and a hot wire in a low speed jet flow (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The study involves a simultaneous measurement with both instruments along radial scans at two axial locations in the jet exiting from the turbulent pipe and an axial scan at the 75-percent radial location in the jet from the convergent nozzle. The results suggest that, within the limits of flow stationarity, both instruments yield measurements in good agreement, + or - 0.8-percent in turbulence intensity, below a turbulence intensity (the ensemble standard deviation divided by the local mean velocity) of 20 percent. From turbulence intensities of 20 percent to a maximum of 75 percent, the measurements exhibit the same trends; for reasons discussed here, however, the comparisons are not of the quality as those below 20 percent. It is found that correcting the turbulence intensity data for velocity bias errors increases the results by an average of 2 percent in turbulence intensity above the hot wire results and the uncorrected laser velocimeter data. The results are seen as calling into question the validity of using the velocity bias correction and time average techniques for turbulence intensity measurements.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
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  • 8
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    Holographic Twyman-Green interferometer (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A dichromated gelatin off-axis Fresnel zone plate was designed, fabricated, and used in a new type of interferometer for optical metrology. This single hologram optical element combines the functions of a beam splitter, beam diverger, and aberrated null lens. Data presented show the successful application for an interferometric test of an f/6, 200-mm diam parabolic mirror.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics; 21; July 15
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  • 9
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    SAR imaging - Seeing the unseen (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The functional abilities and operations of synthetic aperture radar (SAR) are described. SAR employs long wavelength radio waves in bursts, imaging a target by 'listening' to the small frequency changes that result from the Doppler shift due to the relative motion of the imaging craft and the motions of the target. The time delay of the signal return allows a determination of the location of the target, leading to the build up of a two-dimensional image. The uses of both Doppler shifts and time delay enable detailed imagery which is independent of distance. The synthetic aperture part of the name of SAR derives from the beaming of multiple pulses, which result in a picture that is effectively the same as using a large antenna. Mechanisms contributing to the fineness of SAR images are outlined.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Sky and Telescope; 63; Feb. 198
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  • 10
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    Photoacoustic cell using elliptical acoustic focusing (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A photoacoustic cell has been developed in the form of an elliptical cylinder in which essentially all the acoustic energy generated by a laser beam passing down one axis is focused onto a cylindrical acoustic tranducer located along the other axis. Preliminary measurements on a liquid-filled cell of this design show high sensitivity and a notably clean impulse response. A similar design may be useful for photoacoustic measurements in vapors as well.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics; 21; Jan. 1
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  • 11
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    Water Raman normalization of airborne laser fluorosensor measurements - A computer model study (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The technique for normalizing airborne lidar measurements of chlorophyll fluoresence by the water Raman scattering signal is investigated for laser-excitation wavelengths of 480 and 532 nm using a semianalytic Monte Carlo methodology (SALMON). The signal-integration depth for chlorophyll fluorescence Z(90,F), is found to be insensitive to excitation wavelength and ranges from a maximum of 4.5 m in clearest waters to less than 1 m at a chlorophyll concentration of 20 microgram/liter. For excitation at 532 nm, the signal-integration depth for Raman scattering, Z(90,R), is comparable to Z(90,F). For excitation at 480 nm, Z(90,R) is four times as large as Z(90,F) in clearest waters but nearly equivalent at chlorophyll concentrations greater than 2-3 microgram/liter. Absolute signal levels are stronger with excitation at 480 nm than with excitation at 532 nm, but this advantage must be weighed against potential ambiguities resulting from different integration depths for the fluorescence and Raman scattering signals in clearer waters. To the precision of the simulations, Raman normalization produces effectively linear response to chlorophyll concentration for both excitation wavelengths.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics; 21; Oct. 15
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  • 12
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    Shuttle experiment to demonstrate high-accuracy global time and frequency transfer (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The concept of a high-accuracy global time and frequency transfer system is discussed. A hydrogen maser clock onboard a space vehicle combined with a microwave Doppler cancellation system can provide direct frequency transfer with an accuracy of 10 to the -14th and time transfer accurate to 1 ns. The addition of short pulse laser techniques provides subnanosecond time transfer accuracy which can be used to calibrate the microwave system.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
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  • 13
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    Validation of the BUV satellite ozone sensor using the rocket ozonesonde (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Satellite instruments such as the backscattered ultraviolet (BUV) apparatus, have been in operation for a number of years. One current difficulty is the validation of the ozone inferences obtained from the BUV measurements using independent instruments. For higher altitudes rocket instruments are necessary. Two instruments currently under development include a chemiluminescent detector described by Hilsenrath et al. (1969) and a filter photometer rocket ozonesonde (Rocoz) developed by Krueger and McBridge (1968). The present investigation is concerned with an analysis of the Rocoz system, the information content of the measurements, and the utility of the system for intercomparison with the BUV system. It is found that the sampling characteristics of the Rocoz and BUV systems exhibit some fundamental differences. However, their results can be related through knowledge of the relation between pressure and altitude. This is best obtained through the solution of the hypsometric equation using rocket temperature measurements.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics; 21; July 1
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  • 14
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    An intercomparison of ground-based total ozone instruments (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Five ground-based total ozone spectrophotometers were intercompared at Wallops Island, VA between October 1979 and January 1981. The tests were conducted to evaluate the stability and accuracy of each instrument over an extended time period. Acceptable performance regarding these two characteristics is essential if an instrument is to be useful in field measurements and network monitoring of the atmospheric total ozone content. The Dobson spectrophotometer was used as the standard of comparison for the Brewer grating spectrophotometer, the USSR M-83 ozonometer, the Canterbury filter photometer, and the SenTran filter photometer. The grating instrument was found to be potentially the equal of the Dobson but was subject to unreliable performance by its rather sophisticated electronic components. The filter photometers performed acceptably for short periods but filter aging and eventual degradation rendered both units unusable before the end of the intercomparison. Finally, the M-83 results were found to be in acceptable agreement with the Dobson throughout the period when certain qualifications are invoked. The accuracy of a single M-83 ozone measurement may be low. Averages tend to improve its agreement with the Dobson.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Journal of Applied Meteorology; 21; May 1982
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  • 15
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    A report from the AVS Standards Committee - Comparison of ion gauge calibrations by several standards laboratories (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Calibrations by four U.S. laboratories of four hot-cathode ion gauges, in the range 0.07-13 mPa, showed systematic differences among laboratories that were much larger than the expected error of any one calibration. They also suggested that any of the four gauges tested, if properly packaged and shipped, was able to serve as a transfer standard with probable error of 2%. A second comparison was made of the calibrations by two U.S. laboratories of some other gauges that had also been calibrated by the National Physical Laboratory, England. Results did not permit conclusive determination of whether differences were due to the laboratories or to changes in the gauges.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Journal of Vacuum Science and Technology; 20; Jan. 198
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  • 16
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    Delineation of estuarine fronts in the German Bight using airborne laser-induced water Raman backscatter and fluorescence of water column constituents (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The acquisition and application of airborne laser induced emission spectra from German Bight water during the 1979 MARSEN experiment is detailed for the synoptic location of estuarine fronts. The NASA Airborne Oceanographic Lidar (AOL) was operated in the fluorosensing mode. A nitrogen laser transmitter at 337.1 nm was used to stimulate the water column to obtain Gelbstoff or organic material fluorescence spectra together with water Raman backscatter. Maps showing the location and relative strength of estuarine fronts are presented. The distribution of the fronts indicates that mixing within the German Bight takes place across a relatively large area. Reasonable agreement between the patterns observed by the AOL and published results are obtained. The limitations and constraints of this technique are indicated and improvements to the AOL fluorosensor are discussed with respect to future ocean mapping applications.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: International Journal of Remote Sensing; 3; Oct
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  • 17
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    Measurements of ocean surface spectrum from an aircraft using the two-frequency microwave resonance technique (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The present investigation is concerned with the results of a two-frequency (Delta k) microwave radar experiment conducted from an aircraft and aimed primarily at the development of remote sensing techniques to measure ocean surface wave spectral characteristics. The experiment was conducted as part of the Maritime Remote Sensing (MARSEN) project in the North Sea during the autumn of 1979. The objective was to demonstrate the feasibility of and study the performance of the Delta k technique from a higher altitude platform, at shallower incidence angles, and at higher Doppler velocities than earlier stationary platform experiments allowed. A quantitative engineering evaluation of the results of two comprehensive flights is provided, and the qualitative significance of the results is discussed from a geophysical point of view in terms of the existing theory.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: International Journal of Remote Sensing; 3; Oct
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  • 18
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    Dual-wavelength correlation measurements with an airborne pulsed carbon dioxide lidar system (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Dual-wavelength correlation data are presented for ground-level and airborne measurements of topographic and ocean backscatter near the 9.5-micron wavelength. Data were acquired with a pulsed carbon dioxide, dual-laser, dual-wavelength lidar system. The best system performance gave a dual-wavelength uncorrelated noise component of 2.8% and 9% standard deviation for ground-based and airborne data, respectively. This sets one limit on lidar measurement accuracy with a single pulse pair.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Optics Letters; 7; Dec. 198
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  • 19
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    Radiation effects in IRAS extrinsic infrared detectors (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: During the calibration and testing of the Infrared Astronomy Satellite (IRAS) focal plane, it was observed that the extrinsic photoconductor detectors were affected by gamma radiation at dose levels of the order of one rad. Since the flight environment will subject the focal plane to dose levels of this order from protons in single pass through the South Atlantic Anomaly, an extensive program of radiation tests was carried out to measure the radiation effects and to devise a method to counteract these effects. The effects observed after irradiation are increased responsivity, noise, and rate of spiking of the detectors after gamma-ray doses of less than 0.1 rad. The detectors can be returned almost to pre-irradiation performance by increasing the detector bias to breakdown and allowing a large current to flow for several minutes. No adverse effects on the detectors have been observed from this bias boost, and this technique will be used for IRAS with frequent calibration to ensure the accuracy of observations made with the instrument.
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  • 20
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    Microwave remote sensing: Active and passive. Volume 2 - Radar remote sensing and surface scattering and emission theory (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The fundamental principles of radar backscattering measurements are presented, including measurement statistics, Doppler and pulse discrimination techniques, and associated ambiguity functions. The operation of real and synthetic aperture sidelooking airborne radar systems is described, along with the internal and external calibration techniques employed in scattering measurements. Attention is given to the physical mechanisms responsible for the scattering emission behavior of homogeneous and inhomogeneous media, through a discussion of surface roughness, dielectric properties and inhomogeneity, and penetration depth. Simple semiempirical models are presented. Theoretical models involving greater mathematical sophistication are also given for extended ocean and bare soil surfaces, and the more general case of a vegetation canopy over a rough surface.
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  • 21
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    Spaceborne synthetic-aperture imaging radars - Applications, techniques, and technology (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: In June 1978, the Seasat satellite was placed into orbit around the earth with a synthetic-aperture imaging radar (SAR) as one of the payload sensors. The Seasat SAR provided, for the first time, synoptic radar images of the earth's surface with a resolution of 25 m. In November 1981, the second imaging radar was successfully operated from space on the Shuttle. The Shuttle Imaging Radar-A acquired images over a variety of regions around the world with an imaging geometry different from the one used by the Seasat SAR. The spaceborne SAR principle is discussed, taking into account ambiguities, orbital and environmental factors, range curvature and range walk, surface interaction mechanisms, thermal and speckle noise, key tradeoff parameters, and nonconventional SAR systems. Attention is also given to spaceborne SAR sensors, the digital processing of spaceborne SAR data, the optical processing of spaceborne SAR data, postimage formation processing, data interpretation techniques and applications, and the next decade.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: IEEE; vol. 70
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  • 22
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    Role of passive remote sensors. Sensor System Panel report (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Capabilities of present passive systems are described and the development of passive remote sensing systems for the more abundant tropospheric trace species is recommended. The combination of nadir-viewing spectrometers and solar occultation for tropospheric measurement of those gases having large stratospheric burdens is discussed. Development of a nadir-viewing instrument capable of obtaining continuous spectra in narrower bands is recommended. Gas filter radiometers for species specific measurements and development of a spectral survey instrument are discussed. Further development of aerosol retrieval algorithms, including polarization techniques, for obtaining aerosol thickness and size distributions is advised. Recommendations of specific investigations to be pursued are presented.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Tropospheric Passive Remote Sensing; p 35-54
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  • 23
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    Tropospheric passive remote sensing: Introduction (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Measurement needs regarding chemical and transport parameters were identified. Measurement of those gases involved in tropospheric photochemistry (O3, CO, CH4, NOx, HNO3, SO2, NH3, and CH3CCl3) and quantification of their sources and sinks, as well as a fundamental understanding of atmospheric chemical transformations were discussed. The photochemistry of OH and its role as a sink are summarized. The concentrations and lifetimes of the tropospheric gases were considered. Major concerns in tropospheric transport are the making of representative remote measurements of trace gases and aerosols and the dependence of these measurements on structural differences in the atmosphere.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Tropospheric Passive Remote Sensing; p 3-34
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  • 24
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    Technology thrusts for passive remote sensing. Sensing Technology Panel report (1982)
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    Publication Date: 2011-08-18
    Description: Technology thrusts for broadband spectrometry and gas filter radiometry development are identified. The development of 'smart' processing and cryogenics/cooling systems for all types of broadband spectrometers is advised. The use of large fixed gratings and the development of 1000-element arrays is recommended. Improvements suggested for interferometers are: the mitigation of background fluctuations; the development of multiaperature, multiband interferometers; and provision of in-flight alignment verification. Specifically recommended for gas filter radiometers are the development of gas filter cell technology, of liner and high dynamic range detectors, and of high uniform optical elements.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Tropospheric Passive Remote Sensing; p 55-71
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  • 25
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    Analysis of DSN PPM support during Voyager 2 Saturn encounter (1982)
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    Publication Date: 2011-08-18
    Description: The precision power monitor (PPM) is a precision radiometric instrument used to improve the efficiency of signal reception by the Deep Space Network. Real time estimates of the system operating temperature, the present (signal + noise)-to-noise ratio, and the signal power are utilized to increase the accuracy and resolution of the received spacecraft signal. Due to the critical nature of radio science data returning from Voyager 2 at Saturn Encounter, PPM support was required. The task was undertaken to validate the performance of equipment technically under research and development in time to meet the encounter deadline. Initial studies revealed PPM performance to be out of tolerance. Action was immediately taken to identify the system problems. Using data analysis as feedback, the system failures were identified and corrected in time to contribute to the encounter support efforts. As a result, the radio science data were collected successfully.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: The Telecommun. and Data Acquisition Rept.; p 139-150
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  • 26
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    Laser velocimeter for large wind tunnels (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The measurement of velocity in large wind tunnels is normally performed using mechanical probes. This practice can entail considerable complexity in connection with the structure often required for probe support. The use of laser velocimetry for the flowfield measurements in large wind tunnels is, therefore, far more desirable since it can be implemented with minimal mechanical complexity and with minimal modifications to the test section structure. A description is provided of a velocimeter which is intended for use in investigations which include V/STOL vehicle flowfield mapping for location and sizing of wakes and plumes, wing-loading distribution determination without the need for pressure taps, the aerodynamics of high-lift airfoils as well as rotating rotor blades, and vehicle wake studies. Use is made of a single-color dual-beam backscatter system which is capable of sensing two orthogonal components of velocity.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Journal of Aircraft; 19; Dec. 198
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  • 27
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    Passive microwave detection of river-plume fronts in the German Bight (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The NASA P-3 aircraft with the L- and S-band radiometer system on board participated in the MARSEN experiments carried out between August 30 and September 23, 1979. Measurements of surface temperature and salinity were concentrated on freshwater outflows of the Rivers Weser and Elbe in the German Bight. Three missions were carried out, on September 19, 22, and 23. The values of salinity are plotted as a function of geographic position, and contour maps of the salinity distribution are generated from the value plots. It is noted that on September 22, during a noon flood-tide, two river-plume salinity fronts were detected when a body of water with higher salinity existed in front of the Weser delta near Bremerhaven generating with the river outflow of lower saline waters a front of delta-S equals 5 per thousand. Another pocket of lower saline waters was found in front of the Elbe delta at Cuxhaven, which in turn set up a strong front of delta-S equals 6 per thousand. The morning low tide of September 23 did not exhibit this extreme condition.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: International Journal of Remote Sensing; 3; Oct
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  • 28
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    Two-dimensional convolute integers for analytical instrumentation (1982)
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    Publication Date: 2011-08-18
    Description: As new analytical instruments and techniques emerge with increased dimensionality, a corresponding need is seen for data processing logic which can appropriately address the data. Two-dimensional measurements reveal enhanced unknown mixture analysis capability as a result of the greater spectral information content over two one-dimensional methods taken separately. It is noted that two-dimensional convolute integers are merely an extension of the work by Savitzky and Golay (1964). It is shown that these low-pass, high-pass and band-pass digital filters are truly two-dimensional and that they can be applied in a manner identical with their one-dimensional counterpart, that is, a weighted nearest-neighbor, moving average with zero phase shifting, convoluted integer (universal number) weighting coefficients.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Analytical Chemistry; 54; 9, Au; Aug. 198
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  • 29
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    The MSFC vector magnetograph (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: (Previously announced in STAR as N82-27210)
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Solar Physics; 80; Sept
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  • 30
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    Light ion mass spectrometer for space-plasma investigations (1982)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Direct satellite measurements and ground-based techniques have given a comprehensive view of the density distribution of the cold plasma population in the earth's magnetosphere. There were, however, no direct measurements of the low-energy plasma mass composition, temperature, density, pitch-angle distribution, or plasma flow velocity. A description is presented of the evolution and development of an instrument, the Light Ion Mass Spectrometer (LIMS), designed to make these low-energy plasma measurements. The instrument was developed for flight on the spacecraft SCA-THA, a satellite to study satellite charging at high altitudes. This satellite, whose primary mission was to study spacecraft-plasma interactions and electrostatic charging, was launched into a near-geosynchronous orbit. The design requirements regarding the instrument are discussed, and attention is given to the calibration procedures, the flight configuration, and some examples of flight data.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Review of Scientific Instruments; 53; Apr. 198
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  • 31
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    Can the standard radiosonde system meet special atmospheric research needs (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: As a part of a rather comprehensive study of instrument reliability and error analysis, 21 balloon-borne dual radiosonde flights were launched and tracked with a precision C-band (FPS-16) radar as well as with the usual radiosonde tracking system. Radar provides an independent means for obtaining altitude data of order 10 meter accuracy. The 18 successful flights were investigated to determine repeatability of the pressure and temperature measurements. The obtained results show that the current aneroid pressure cell is the least repeatable member of the radiosonde's measurement components. Generally, the rms differences of the pressure measurements were found to be between 1 and 2 mbar throughout the altitude range of the instrument. Although these errors are large, they are not serious in the context of synoptic use. However, serious consideration must be given to these instrumental characteristics in connection with single station, nonsynoptic research objectives.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Geophysical Research Letters; 9; Sept
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  • 32
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    Measurement of the dispersive and refractive indices of germanium using diode lasers (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Germanium Fabry-Perot etalons are commonly used in diode laser spectroscopy to establish relative frequency calibration scales for molecular absorption spectra. Typically the channel spectrum of the etalon is recorded simultaneously with the molecular spectrum as the laser injection current is tuned linearly, and the etalon free spectral range (fringe spacing) is used to measure the frequency separations among lines in the molecular spectrum. For this purpose, the etalon free spectral range must be known for the measurement wavelength, and this in turn relies on knowledge of the etalon length and the dispersive index at this wavelength. It is pointed out that the most satisfactory approach is to measure directly the free spectral range or dispersive index of the etalon at the wavelength of interest. A description is presented of measurements of this type, performed near 7.9 and 10.1 micrometers for a 7.7-cm long germanium etalon.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics; 21; Sept. 15
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  • 33
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    Image sampling, reconstruction, and the effect of sample-scene phasing (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: This paper is a 1-D analysis of the degradation caused by image sampling and interpolative reconstruction. The analysis includes the sample-scene phase as an explicit random parameter and provides a complete characterization of this image degradation as the sum of two terms: one term accounts for the mean effect of undersampling (aliasing) and nonideal reconstruction averaged over all sample-scene phases; the other term accounts for variations about this mean. The results of this paper have application to the design and performance analysis of image scanning, sampling, and reconstruction systems.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics; 21; Sept. 1
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  • 34
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    A hot-film static-pressure probe (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The procedure described involves calibrating the probe in the gas of interest over the range of temperatures and pressures anticipated in the wind-tunnel tests and then applying the calibration to reduce the data from those tests. Pressure readings from two probes, one having two hot-film sensors and an internal sonic orifice and the other connected to a conventional pressure gage, are recorded for several Reynolds numbers and compared. The conventional static-pressure probe with a pair of hot-film sensors and an interior sonic orifice is shown to provide the means of surveying flowfields in hypersonic flow at a rapid rate and with an accuracy of better than + or - 10%.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: AIAA Journal; 20; July 198
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  • 35
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    Interferometry and holography in a low-gravity environment (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The groundwork for the use of advanced optical measurement techniques in Space Shuttle materials processing in space (MPS) experiments is being laid in tests, conducted aboard a NASA KC-135 aircraft flying a parabolic trajectory, involving a Mach-Zehnder interferometer and a sideband holographic unit. The two experiments described are (1) the observation of flow during solidification, in which fluid concentration and temperature profiles were measured during unidirectional solidification of a saturated NH4Cl-H2O solution, and (2) the observation of electrodeposition flow, in which interferometry is used to provide quantitative data required in the understanding of electrochemical process transport properties. The free-floating holographic unit was operated in the microgravity environment to both test the practicality of optical systems in such conditions and test the shock and vibration characteristics of the package.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics; 21; Apr. 15
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  • 36
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    High resolution atmospheric spectroscopy using a diode laser heterodyne spectrometer (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Ultrahigh resolution (0.007 per cm) atmospheric solar absorption spectra that have been obtained from a tunable infrared heterodyne radiometer are discussed. The radiometer was developed for ground based observations in the 8-12 micron region, and tunability is achieved through the use of Pb-salt semiconductor laser local oscillators. Spectra have been obtained in a piecewise fashion from 9.1 to 11.1 microns using laser emission modes that exhibit characteristics suitable for local-oscillator operation. Spectra showing absorption features of HNO3, O3, CO2, and H2O are presented along with comparisons of experimental and synthetic spectra calculated using a line-by-line atmospheric transmission model.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Optical Engineering; 21; Mar
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  • 37
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    Color visualization for fluid flow prediction (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: High-resolution raster scan color graphics allow variables to be presented as a continuum, in a color-coded picture that is referenced to a geometry such as a flow field grid or a boundary surface. Software is used to map a scalar variable such as pressure or temperature, defined on a two-dimensional slice of a flow field. The geometric shape is preserved in the resulting picture, and the relative magnitude of the variable is color-coded onto the geometric shape. The primary numerical process for color coding is an efficient search along a raster scan line to locate the quadrilteral block in the grid that bounds each pixel on the line. Tension spline interpolation is performed relative to the grid for specific values of the scalar variable, which is then color coded. When all pixels for the field of view are color-defined, a picture is played back from a memory device onto a television screen.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Mechanical Engineering; 104; Mar. 198
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  • 38
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    Energetic ion mass spectrometer (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A new type of spectrometer for space application has been developed to measure separately mass/charge and the three-dimensional velocity distribution of incident ions. The instrument has relatively high resolution and allows rapid measurement of the four-dimensional set of mass/charge, speed, elevation angle, and azimuth angle. The instrument includes a sector magnet, an electrostatic deflector, microchannel plate detectors with position sensitive readout, and a set of grids with variable applied voltage.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Review of Scientific Instruments; 53; Mar. 198
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  • 39
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    Holographic cinematography of time-varying reflecting and time-varying phase objects using a Nd:YAG laser (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The use of a Nd:YAG laser to record holographic motion pictures of time-varying reflecting objects and time-varying phase objects is discussed. Sample frames from both types of holographic motion pictures are presented. The holographic system discussed is intended for three-dimensional flow visualization of the time-varying flows that occur in jet-engine components.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Optics Letters; 7; Mar. 198
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  • 40
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    Laser Doppler anemometer measurements using nonorthogonal velocity components - Error estimates (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Laser Doppler anemometers (LDAs) that are arranged to measure nonorthogonal velocity components (from which orthogonal components are computed through transformation equations) are more susceptible to calibration and sampling errors than are systems with uncoupled channels. In this paper uncertainty methods and estimation theory are used to evaluate, respectively, the systematic and statistical errors that are present when such devices are applied to the measurement of mean velocities in turbulent flows. Statistical errors are estimated for two-channel LDA data that are either correlated or uncorrelated. For uncorrelated data the directional uncertainty of the measured velocity vector is considered for applications where mean streamline patterns are desired.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics; 21; Jan. 15
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  • 41
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    Tunable diode-laser heterodyne spectrometer for remote observations near 8 microns (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A diode-laser-based, ultrahigh resolution IR heterodyne spectrometer for laboratory and field use has been developed for operation between 7.5 and 8.5 microns. The local oscillator is a PbSe tunable diode laser kept continuously at operating temperatures of 12-60 K using a closed-cycle cooler. The laser output frequency is controlled and stabilized using a high-precision diode current supply, constant temperature controller, and a shock isolator mounted between the refrigerator cold tip and the diode mount. The system largely employs reflecting optics to minimize losses from internal reflection and absorption and to eliminate chromatic effects. Spectral analysis of the diode-laser output between 0 and 1 GHz reveals excess noise at many diode current settings, which limits the IR spectral regions over which useful heterodyne operation can be achieved. Observations have been made of atmospheric N2O, O3, and CH4 between 1170 and 1200/cm, using both a single-frequency swept IF channel and a 64-channel RF spectral line receiver with a total IF coverage of 1600 MHz.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics; 21; Jan. 15
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  • 42
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    Mass spectrometry in the stratosphere (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A gas expansion system incorporating a mass spectrometer that has been successfully flown in the stratosphere is described. Neutral gas particles are formed into a molecular beam that traverses the ion source of the mass spectrometer without wall interactions. It is noted that vertical profiles of such constituents as H2O, CO2, and O3 have been measured in the altitude range of 20 to 40 km during balloon descents. Isotopes of important gases (N2, O2, Ar) provided in-flight calibration standards. Before each flight the mass spectrometer system is calibrated in the laboratory for many gases of interest, including ozone. Mixing ratios of ozone established from recent flights have accuracies of better than 5 percent. The sensitivity of the system is sufficient to detect as well the heavy isotope of ozone at mass 50. A noticeable enhancement of heavy ozone in the upper stratosphere has been found. The mass spectrometer system is seen as providing a unique opportunity to perform in situ measurements in the stratosphere in combination with isotopic studies.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: (ISSN 0273-1177)
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  • 43
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    Imaging spectrometer technologies for advanced earth remote sensing (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A major requirement of multispectral imaging systems for advanced earth remote sensing is the provision for greater spectral resolution and more versatile spectral band selection. The imaging spectrometer instrument concept provides this versatility by the combination of pushbroom imaging and spectrally dispersing optics using area array detectors in the focal plane. The shuttle imaging spectrometer concept achieves 10- and 20-meter ground instantaneous fields of view with 20-nanometer spectral resolution from earth orbit. Onboard processing allows the selection of spectral bands during flight; this, in turn, permits the sensor parameters to be tailored to the experiment objectives. Advances in optical design, infrared detector arrays, and focal plane cooling indicate the feasibility of the instrument concept and support the practicability of a validation flight experiment for the shuttle in the late 1980s. Previously announced in STAR as N83-28542
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  • 44
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    Precision manipulator heating and cooling assembly compatible with sample transfer (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A technique is described for the transfer of a UHV sample system to a precision manipulator. It allows direct sample temperature measurement in a broad range of sample temperatures (150-1750 K) and simultaneously retains the benefit of the additional degree of freedom provided by the precision manipulator flip mechanism. The technique is similar to that reported by Crider (1976) but with several modifications. The pump is mounted at the extreme end of the magnetically coupled linear motion feedthrough (to maximize the separation). Samples are mounted on a threaded circular sample holder, transferred to the flip mechanism of the manipulator. The flip mechanism contains a rear electrode assembly and thermocouple, in direct contact with the sample, and a copper plate and a flexible strap are attached to the receiving block (to facilitate sample cooling).
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Journal of Vacuum Science and Technology (ISSN 0022-5355); 21; 1037
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  • 45
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    The HCMM system: Development and performance (1982)
    In:  Other Sources
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    Publication Date: 2019-01-25
    Description: The structure and history of the heat capacity mapping mission program is reviewed and the spacecraft is described including engineering specifications, instrument design, data handling, and image characteristics.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: The Heat Capacity Mapping Mission (HCMM) Anthology; p 245-260
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  • 46
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    Development of test methodology for dynamic mechanical analysis instrumentation (1982)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Dynamic mechanical analysis instrumentation was used for the development of specific test methodology in the determination of engineering parameters of selected materials, esp. plastics and elastomers, over a broad range of temperature with selected environment. The methodology for routine procedures was established with specific attention given to sample geometry, sample size, and mounting techniques. The basic software of the duPont 1090 thermal analyzer was used for data reduction which simplify the theoretical interpretation. Clamps were developed which allowed 'relative' damping during the cure cycle to be measured for the fiber-glass supported resin. The correlation of fracture energy 'toughness' (or impact strength) with the low temperature (glassy) relaxation responses for a 'rubber-modified' epoxy system was negative in result because the low-temperature dispersion mode (-80 C) of the modifier coincided with that of the epoxy matrix, making quantitative comparison unrealistic.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Marshall Space Flight Center The 1982 NASA(ASEE Summer Fac. Fellowship Program; 24 p
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  • 47
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    Laser Doppler velocimetry application in the Langley 0.3-meter Transonic Cryogenic Tunnel (1982)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The problems and the potential use of a nonintrusive flow velocity measuring technique in the Langley 0.3 meter transonic cryogenic tunnel (TCT) were investigated. A laser velocimeter (LV) was used. It was concluded that free-stream velocity measurements can be successfully made in the Langley 0.3-m TCT using a low-power (15-mW) LV system. The measured and calculated mean velocities typically agreed within one percent. The overall normalized standard deviation was less than one percent. Tunnel vibration and temperature had no detrimental effects on the optical system. It is recommended that the LV work should be further investigated for future use in the Langley 0.3-m TCT.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Flow Visualization and Laser Velocimetry for Wind Tunnels; p 323-334
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  • 48
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    Velocity and flow angle measurements in the Langley 0.3-meter transonic cryogenic tunnel using a laser transit anemometer (1982)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The Laser Transit Anemometer (LTA) system is described. In the LTA system two parallel laser beams of known separation and cross sectional area are focussed at the same location or plane. When a particle in a flow field passes through both beams and the time is recorded for its transit (time of flight), its velocity can be calculated knowing the distance between the beams. By rotating the two beams (spots) around a common center and recording the number of valid events (a particle which passes through both spots in the proper sequence) at each angle the flow angle can be determined by curve fitting a predetermined number of angles or points and calculating the peak of what should be a Gaussian curve. The best angle or flow angle is defined as the angle at which the maximum number of valid events occurs. The LTA system functioned properly although conditions were less than desirable.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Flow Visualization and Laser Velocimetry for Wind Tunnels; p 335-342
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  • 49
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    Application of the laser Doppler velocimeter in aerodynamic flows (1982)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Applications of the laser doppler velocimeter (LDV) are discussed. Measurements were made of the flowfield around a tangent-ogive model in a low turbulent, incompressible flow at an incidence of 45 deg. The free-stream velocity was 80 ft per second. The flowfield velocities in several cross-flow planes were measured with a 2-D, two-color LDC operated in a backscatter mode. Measurements were concentrated in the secondary separation region. A typical survey is given. The survey was taken at a model location where the maximum side force occurs. The overall character of the leeward flowfield with the influence of the two body vorticles are shown. Measurements of the velocity and density flowfields in the shock-layer region of a reentry-vehicle indented nose configuration were carried out at Mach 5. The velocity flowfield was measured with a 2-color, 2-D, forward-scatter LDV system. Because of the need to minimize particle lag in the shock-layer region, polystyrene particles with a mean diameter of 0.312 microns were used for the scattering particles. The model diameter was 6 inches.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Langley Research Center Flow Visualization and Laser Velocimetry for Wind Tunnels; p 295-302
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  • 50
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    LV measurements with an advanced turboprop (1982)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Nonintrusive measurements of velocity about a spinner-propeller-nacelle configuration were made at a Mach number of 0.8. A laser velocimeter (LV) specifically developed for these measurements was used to determine the flow field of the advanced swept SR-3 propeller. The data will be used to study the flow and to verify computer prediction codes. The usefulness of the LV data in detecting flow anomalies and to substantiate the data quality was demonstrated. Some typical results are given. Mach number profiles at the entrance of the propeller are compared with theoretical predictions. The LV data is in excellent agreement with the axisymmetric, compressible, inviscid theory (without blades) ahead of the propeller except near the hub. The data indicate blade blockage near the spinner. Blade to blade variations in axial velocity for four radial positions at the propeller exist are also given. The large apparent wake near the hub is associated with the hub choking. The blade to blade variation of axial velocity ahead of a shock within the blade passage is given.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Langley Research Center Flow Visualization and Laser Velocimetry for Wind Tunnels; p 253-256
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  • 51
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    Flow visualization efforts and pilot measurements with a laser-Doppler anemometer in backscatter mode (1982)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Activities involving the use flow visualization and laser anemometers are reviewed. In particular, turbulent pipe flow measurements and local velocity determination in a 3 X 3 sq meter wind tunnel are discussed. The calibration of laser anemometer systems using a rotating disk is also addressed.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Langley Research Center Flow Visualization and Laser Velocimetry for Wind Tunnels; p 235-241
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  • 52
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    Development of a laser velocimeter for a large transonic wind tunnel (1982)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: On a 8 x 6 Foot Supersonic Wind Tunnel a laser velocimeter was utilized in the testing of advanced high speed turbopropellers. The system, using a 15-W argon-ion laser, a 3-beam 2-axis transmitting-receiving optics package, a zoom lens with 1- to 4-m focal lengths, and a 0.4-m corner mirror was initially assembled and tested in the checkout room. During the time the system was located in the checkout area, experience was acquired in the alignment and operation of the system and the data acquisition system and software were developed. By using air jets to simulate tunnel air flow, the system worked quite well. However, problems with beam alignment arose because of reduced atmospheric pressure. Mounting the laser into a vessel maintained at atmospheric pressure with deflectors mounted to the external walls improved operation for about 2 hours before misalignment reoccurred. The system was remounted to the positioning platform in an enclosure that provides both thermal and acoustic isolation.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Langley Research Center Flow Visualization and Laser Velocimetry for Wind Tunnels; p 243-247
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  • 53
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    Status of laser anemometry in turbomachinery research at the Lewis Research Center (1982)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Laser anemometer systems were developed for a full-annular turbine stator cascade facility and for a compressor rotor facility; both are ambient temperature axial flow facilities with a 20-inch tip diameter. The optical configurations of the two anemometers are similar single-component fringe-type backscatter systems with a probe volume diameter of 125 microns and length of about 2 mm. Laser anemometer measurements are compared with numerical solutions for a transonic axial flow compressor rotor and a turbine stator cascade.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Langley Research Center Flow Visualization and Laser Velocimetry for Wind Tunnels; p 227-234
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  • 54
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    Laser velocimetry: A state-of-the-art overview (1982)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: General systems design and optical and signal processing requirements for laser velocimetric measurement of flows are reviewed. Bias errors which occur in measurements using burst (counter) processors are discussed and particle seeding requirements are suggested.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Langley Research Center Flow Visualization and Laser Velocimetry for Wind Tunnels; p 205-214
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  • 55
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    The 16-foot transonic tunnel laser velocimeter system (1982)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The Langley 16-foot transonic wind tunnel is described. The system configuration, optical layout, laser color separator, optical receiver, and tunnel window are discussed.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Flow Visualization and Laser Velocimetry for Wind Tunnels; p 257-272
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  • 56
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    Laser velocimeter applications to high-lift research (1982)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The application of the Lockheed-Georgia 2-D laser velocimeter (LV) burst-counter system to the flow field around a 2- and 3-element high-lift airfoil is discussed. The characteristic behavior of the confluent boundary layer (that is, the boundary layer existing downstream of a slot as it approaches and undergoes separation is evaluated. In this application, the LV represents all ideal instruments for nonintrusively probing into the narrow slots and cove areas characterizing mechanical high-lift systems. The work is being performed in the Lockheed-Georgia 10 x 30-inch low-speed test facility using a 9-inch (basic) chord section of the general aviation GAW-1 airfoil. The LV system employs a 4-W argon laser and operates in an off-axis, backscatter mode with a focus length of about 30 inches. Smoke is used as the seeding medium and is injected downstream of the model such that particle uniformity and size are constant upon completion of the tunnel circuit into the test area. The LV system is fully automated by utilizing a MAC-16 minicomputer for positioning, data acquisition, and preliminary data reduction.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Langley Research Center Flow Visualization and Laser Velocimetry for Wind Tunnels; p 273-281
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    Seeding considerations for an LV system in a large transonic wind tunnel (1982)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: When it was decided to use a laser velocimeter to measure the properties of propellers, seeding was a great concern since large particles fail to flow and small ones are too small to be seen. Many methods were tried and weeded out by using a Malvern particle sizer. The most promising ones were tested in the tunnel and the laser velocimeter (LV) measurements compared to theoretical values of veocity as the particle approached a blunt nose body along a stagnation streamline. Data obtained from the LV system were compared with the one dimensional particle lag calculation. This figure showed the theoretical velocity over the blunt nose and a velocity profile for 5 um particles. This indicated the particles were approximately 5 um. The seeding method is shown. The seed was atomized by 2 seeders run with all 12 available atomizer jets on. The atomizer seed traveled from these two seeders through four 1 inch tubes 20 feet long to the plenum chamber where this cluster of tubes injected the seed into the air stream. The tubes were located 60 feet from the model and could be moved only by shutting the tunnel down. Future seeding plans are shown.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Langley Research Center Flow Visualization and Laser Velocimetry for Wind Tunnels; p 249-252
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    Measurement potential of laser speckle velocimetry (1982)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Laser speckle velocimetry, the measurement of fluid velocity by measuring the translation of speckle pattern or individual particles that are moving with the fluid, is described. The measurement is accomplished by illuminating the fluid with consecutive pulses of Laser Light and recording the images of the particles or the speckles on a double exposed photographic plate. The plate contains flow information throughout the image plane so that a single double exposure may provide data at hundreds or thousands of points in the illuminated region of the fluid. Conventional interrogation of the specklegram involves illuminating the plate to form Young's fringes, whose spacing is inversely proportional to the speckle separation. Subsequently the fringes are digitized and analyzed in a computer to determine their frequency and orientation, yielding the velocity magnitude and orientation. The Young's fringe technique is equivalent to performing a 2-D spatial correlation of the double exposed specklegram intensity pattern, and this observation suggests that correlation should be considered as an alternative processing method. The principle of the correlation technique is examined.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Langley Research Center Flow Visualization and Laser Velocimetry for Wind Tunnels; p 219-226
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    Coherent Raman spectroscopies for measuring molecular flow velocity (1982)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Various types of coherent Raman spectroscopy are characterized and their application to molecular flow velocity and direction measurement and species concentration and temperature determination is discussed.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Langley Research Center Flow Visualization and Laser Velocimetry for Wind Tunnels; p 215-217
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    Holographic flow visualization: State-of-the-art overview (1982)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Components and system designs of holographic flow visualization techniques are reviewed. Recording materials, lasers, and data processing and display are discussed.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Langley Research Center Flow Visualization and Laser Velocimetry for Wind Tunnels; p 149-158
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    Flow field studies using holographic interferometry at Langley (1982)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Some of the uses of holographic interferometry at Langley Research Center both for flow visualization and for density field determinations are described and tests in cryogenic flows at the Langley 0.3-Meter Transonic Cryogenic Tunnel are discussed. Experimental and theoretical fringe shift data are compared.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Flow Visualization and Laser Velocimetry for Wind Tunnels; p 193-204
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  • 62
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    Seeing through flows in Langley's 0.3-meter Transonic Cryogenic Tunnel (1982)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Viewing problems associated with the measurement of model deformation in cryogenic wind tunnels are discussed. Tests were conducted in the Langley 0.3-Meter Transonic Cryogenic Tunnel to assess viewing capabilities thru the flow field. The effects of condensation and turbulent boundary layers are discussed and a modelling procedure for image degradation is described.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Flow Visualization and Laser Velocimetry for Wind Tunnels; p 133-147
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    Flow visualization in the Langley 0.3-meter Transonic Cryogenic Tunnel and preliminary plans for the National Transonic Facility (1982)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Design problems associated with the integration of flow visualization in cryogenic facilities are discussed. The possible effects from the cryogenic environment (i.e., window distortion due to thermal contraction both in the mounts and in the window material itself and turbulence in the flow due to injected LN2) are examined. The flow visualization techniques studied are schlieren, shadowgraph, moire deflectometry, and holographic interferometry. The test beds for this work are a Langley in-house cryogenic test chamber and the 0.3-Meter Transonic Cryogenic Tunnel.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Flow Visualization and Laser Velocimetry for Wind Tunnels; p 117-132
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  • 64
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    Transonic applications of the Wake Imaging System (1982)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The extension of a rapid flow field survey method (wake imaging system) originally developed for low speed wind tunnel operation, to transonic wind tunnel applications is discussed. The advantage of the system, beside the simplicity and low cost of the data acquisition system, is that the probe position data are recorded as an optical image of the actual sensor and thus are unaffected by the inevitable deflections of the probe support. This permits traversing systems which are deliberately flexible and have unusual motions. Two transverse drive systems are described and several typical data images are given.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Langley Research Center Flow Visualization and Laser Velocimetry for Wind Tunnels; p 109-115
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    Propeller flow visualization techniques (1982)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Propeller flow visualization techniques were tested. The actual operating blade shape as it determines the actual propeller performance and noise was established. The ability to photographically determine the advanced propeller blade tip deflections, local flow field conditions, and gain insight into aeroelastic instability is demonstrated. The analytical prediction methods which are being developed can be compared with experimental data. These comparisons contribute to the verification of these improved methods and give improved capability for designing future advanced propellers with enhanced performance and noise characteristics.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Langley Research Center Flow Visualization and Laser Velocimetry for Wind Tunnels; p 75-89
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    Surface flow visualization using indicators (1982)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Surface flow visualization using indicators in the cryogenic wind tunnel which requires a fresh look at materials and procedures to accommodate the new test conditions is described. Potential liquid and gaseous indicators are identified. The particular materials illustrate the various requirements an indicator must fulfill. The indicator must respond properly to the flow phenomenon of interest and must be observable. Boundary layer transition is the most important phenomenon for which flow visualization indicators may be employed. The visibility of a particular indicator depends on utilizing various optical or chemical reactions. Gaseous indicators are more difficult to utilize, but because of their diversity may present unusual and useful opportunities. Factors to be considered in selecting an indicator include handling safety, toxicity, potential for contamination of the tunnel, and cost.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Langley Research Center Flow Visualization and Laser Velocimetry for Wind Tunnels; p 37-46
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    A color video display technique for flow field surveys (1982)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Color video display techniques for flow field surveys are presented. The following techniques were examined: traverse device, used for flow field surveys above and behind finite wing models; flow chart of data reduction for color video display technique; location of spanwise survey stations above and behind wing; hot wire data at first three survey stations on fully stalled wing; hot wire data at last three stations behind fully stalled wing; hot wire and pitch probe data; magnitude of velocity, yaw angle, pitch angle, and cross flow direction from 5 tube survey at X/C = 2.70 behind fully stalled wing.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Langley Research Center Flow Visualization and Laser Velocimetry for Wind Tunnels; p 47-58
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    The need for an optical transition detection system in the NTF (1982)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Methods for transition detection were studied. The very high test and model costs necessitate testing of any new configuration over a range of Reynolds numbers for correlation with data obtained in conventional tunnels. The Reynolds number variations will be carried out at constant dynamic pressure, i.e., constant aeroelastic condition, by varying test temperature. Boundary layer transition cannot be expected to occur at the full scale location at significantly less than full-scale Reynolds numbers, and transition patterns will change with varying Reynolds number. Knowledge of the location of transition on model surfaces is essential for correct interpretation of drag data. The importance of transition, the limitations of artificial transition fixing, and their relation to the NTF are reviewed. The calculated minimum roughness height to instantaneously trip transition on a model transport wing over a range of Reynolds numbers of interest is shown in the NTF.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Langley Research Center Flow Visualization and Laser Velocimetry for Wind Tunnels; p 27-30
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    Electronic simulation of a barometric pressure sensor for the meteorological monitor assembly (1982)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: An analysis of the electronic simulation of barometric pressure used to self-test the counter electronics of the digital barometer is presented. The barometer is part of the Meteorological Monitor Assembly that supports navigation in deep space communication. The theory of operation of the digital barometer, the design details, and the verification procedure used with the barometric pressure simulator are presented.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: The Telecommun. and Data Acquisition Progr. J.; p 95-103
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    Some NTF laser velocimeter installation and operation considerations (1982)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Two velocimeter techniques were considered as potential candidates for achieving the flow field angularity measurements. The first was the fringe laser Doppler velocimeter, (LDV). A great deal of experience was obtained with this approach at Langley and the literature is rich with papers describing many experimental applications and system performance details. That is, many velocity flow field measurements were conducted with the LDV but not with high resolution precise angularity measurements. The second candidate considered was the two-spot laser transit anemometer, (LTA). This approach was not as extensively used as the LDV technique, but literature does contain experimental applications and system performance details. Again, a lack of high resolution, high precision angularity measurements is noted for the LTA. The results of the study suggested that the LDV and LTA tests and other efforts did not reveal any fundamental problems that would suggest that laser velocimetry is not a viable diagnostic technique for the National Transonic Facility. However, there are a number of engineering problems that need to be solved.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Flow Visualization and Laser Velocimetry for Wind Tunnels; p 343-358
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    Comparison of hot wire/laser velocimeter turbulence intensity measurements (1982)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The question of whether a random measure of particle velocities yields a good statistical estimate of the stationary condition of the turbulence flow field was investigated by comparing hot-wire and laser velocimeter turbulence intensity measurements. Great care was taken to insure that the instrument precision of both the laser velocimeter and hot wire was maximized. In this attempt to reduce the measurement uncertainties in the hot wire, direct digitization of the analog output signal was performed with point-by-point conversion to velocity through a spline fit calibration curve and the turbulence intensity function was calculated statistically. Frequent calibrations of the hot wire were performed using the laser velocimeter as the velocity standard to account for the presence of the small seed particles in the air flow and signal drift in the hot wire.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Flow Visualization and Laser Velocimetry for Wind Tunnels; p 303-322
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  • 72
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    Applications of a laser velocimeter in the Langley 4- by 7-meter tunnel (1982)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Applications of a laser velocimeter in the Langley 4 by 7 meter wind tunnel are discussed. The system configuration is described. The data acquisition, the laser velocimeter traversing, and the particle generating systems are discussed. Flow distribution and rotor wake applications are discussed.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Flow Visualization and Laser Velocimetry for Wind Tunnels; p 283-293
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  • 73
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    Measurement of Three-dimensional Density Distributions by Holographic Interferometry and Computer Tomography (1982)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The use of holographic interferometry to measure two and threedimensional flows and the interpretation of multiple-view interferograms with computer tomography are discussed. Computational techniques developed for tomography are reviewed. Current research topics are outlined including the development of an automated fringe readout system, optimum reconstruction procedures for when an opaque test model is present in the field, and interferometry and tomography with strongly refracting fields and shocks.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Langley Research Center Flow visualization and Laser Velocimetry for Wind Tunnels; p 159-174
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    Holographic interferometry and tomography at Ames Research Center (1982)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: A YAG laser holographic interferometer system and reconstruction laboratory for the Ames 2- by 2-Foot Transonic Wind Tunnel are discussed. This system provides dual plate and double pulse holography for quantitative and qualitative measurements, respectively. Interferometric measurements of two-dimensional airfoils and three-dimensional bodies of revolution for a tomography feasibility study were made. The two-dimensional work included supercritical airfoils, an oscillating airfoil undergoing dynamic stall, and a circulation control airfoil. The tomography experiments centered around hemispherical nose and tangent ogive models. In addition, the tomography work covered the development of a Fourier transform code for the retrieval of the three dimensional density distributions from the interferograms.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Langley Research Center Flow Visualization and Laser Velocimetry for Wind Tunnels; p 179-191
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    Flow visualization of shock-boundary layer interaction (1982)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Two and three-dimensional shock-boundary layer interaction data were obtained from supersonic wind tunnel tests. These interactions are studied both with and without boundary layer bleed. The data verify computational fluid dynamic codes. Surface static pressure, pitot pressure, flow angularity, and bleed rates, are studied by flow visualization techniques. Surface oil flow using fluorescent dye and laser sheet using water droplets as the scattering material are used for flow visualization.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Langley Research Center Flow Visualization and Laser Velocimetry for Wind Tunnels; p 101-108
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    In-flight propeller flow visualization using fluorescent minitufts (1982)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Extension of fluorescent minutuft method to in-flight flow visualization on propellers is described. Extremely thin nylon monofilament for the minitufts, is used in a process of attaching them to the test surface with small drops of lacquer-like adhesive, and the use of fluorescence photography for recording the minituft patterns. Using this method, thousands of minitufts can be applied to small, high speed wind tunnel models without affecting the airflow. The minitufts can remain in place throughout a wind tunnel test, permitting nonintrusive flow visualization data to be acquired at any time.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Langley Research Center Flow Visualization and Laser Velocimetry for Wind Tunnels; p 91-95
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    Shadowgraph techniques in transonic tests with powered nacelles (1982)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Shadowgraph photography techniques in transonic wind tunnel tests are described. The system was used in tests with powered nacelle rings to visualize the shock wave pattern in the exhaust flow. The technique is also used for installed nacelle tests on a floor mounted half model with a turbine powered fan engine simulator.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Langley Research Center Flow Visualization and Laser Velocimetry for Wind Tunnels; p 97-100
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    Operational flow visualization techniques in the Langley Unitary Plan Wind Tunnel (1982)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The unitary plan wind tunnel (UPWT) uses in daily operation are shown. New ideas for improving the quality of established flow visualization methods are developed and programs on promising new flow visualization techniques are pursued. The unitary plan wind tunnel is a supersonic facility, referred to as a production facility, although the majority of tests are inhouse basic research investigations. The facility has two 4 ft. by 4 ft. test sections which span a Mach range from 1.5 to 4.6. The cost of operation is about $10 per minute. Problems are the time required for a flow visualization test setup and investigation costs and the ability to obtain consistently repeatable results. Examples of sublimation, vapor screen, oil flow, minitufts, schlieren, and shadowgraphs taken in UPWT are presented. All tests in UPWT employ one or more of the flow visualization techniques.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Flow Visualization and Laser Velocimetry for Wind Tunnels; p 65-73
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    Surface flow visualization requirements for testing in NTF (1982)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Surface flow visualization is required to be correlated at all the facilities to allow the following: (1) an understanding of the chordwise and spanwise extent of laminar flow; (2) the change in shock location for various trip configurations; (3) the effectiveness of the chosen boundary layer trip (since its specifications will change as a function of Reynolds number); and (4) a comparison of the separation patterns at the buffet conditions. A requirement to tunnel-to-tunnel correlation testing involving the NTF is pointed out. A specification for a surface flow visualization system to be used in the NTF is defined. Recognition of the special limitations in the NTF including physical and visual accessibility, high operating cost, flow contamination requirements, as well as the need for on-line review of the results to develop the final trip configurations in a timely manner, leads to the listed requirements.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Langley Research Center Flow Visualization and Laser Velocimetry for Wind Tunnels; p 31-35
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    New versions of old flow visualization systems (1982)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: A small, modified Mach-Zehnder interferometer placed in series with a much larger schlieren optical system spanning the test section is examined. In one arm of the interferometer, light from the schlieren is focused through a pinhole and recollimating lens to produce a reference beam which interferes with the remaining object beam from the other arm. The object and reference beams are separated only over a small interval following the test section, and differential vibrations are greatly reduced. Color schlieren has technical, as well as aesthetic, advantages over black-and-white schlieren. Since each color is associated with a specific amount of refraction, quantitative evaluation of certain refractive-index fields becomes possible using very simple equations derived from ray trace theory. Rainbow schlieren of an acetylene flame, and the evaluated refractive index distribution are shown. Root-mean-square refractive index fluctuations in homogeneous, isotropic turbulence were determined using the rainbow schlieren, since these fluctuations determine the root-mean-square refraction, which is indicated by the overall color of the image.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Langley Research Center Flow Visualization and Laser Velocimetry for Wind Tunnels; p 59-64
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    The state of the art of conventional flow visualization techniques for wind tunnel testing (1982)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Conventional wind tunnel flow visualization techniques which consist of surface flow methods, tracers, and optical methods are presented. Different surface flow methods are outlined: (1) liquid films (oil and fluorescent dye and UV lighting, renewable film via porous dispenser in model, volatile carrier fluid, cryogenic colored oil dots, oil film interferometry); (2) reactive surface treatment (reactive gas injection, reversible dye); (3) transition and heat transfer detectors (evaporation, sublimation, liquid crystals, phase change paints, IR thermography); and (4) tufts (fluorescent mini tufts, cryogenic suitability). Other methods are smoke wire techniques, vapor screens, and optical methods.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Langley Research Center Flow Visualization and Laser Velocimetry for Wind Tunnels; p 9-26
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    Provisions for nonintrusive flow-evaluation tools in the National Transonic Facility (1982)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The national transonic facility fan driven, closed circuit, continuous flow, pressurized wind tunnel is examined. The test section is 2.500 m x 2.500 m and 7.620 m long with a slotted wall configuration. There are six slots each in the top and bottom walls and two slots per sidewall. To maintain good flow quality and aerodynamic efficiency over the wide range of test capabilities the test section geometry is variable. The position of the test section and bottom walls, the reentry flaps at the rear of the test section slots, and the step height for reentering slot flow are remotely controlled. The test gas may be dry air or nitrogen, which for the elevated temperature (340 K) mode of operation the test medium is normally air, and heat removal is by a water cooled heat exchanger (cooling coil) located at the upstream end of the settling chamber. For the cryogenic mode of operation, heat removal is by evaporation of liquid nitrogen, which is sprayed into the circuit upstream of the fan. By utilizing liquid nitrogen as a coolant, the tunnel test temperature range is variable from 340 to 78 K. When nitrogen is injected into the circuit, venting must occur to maintain a constant pressure. Thermal insulation is installed internal to the pressure shell to minimize energy consumption.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Flow Visualization and Laser Velocimetry for Wind Tunnels; p 1-8
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    Monitor and control equipment for the MV-3 mobile very long baseline interferometry station (1982)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The system, designed around a commercially available process controller, is described. The hardware design, selection of the process control equipment, the design of the interface to other systems, and the analog monitor and process control assembly used to operate the equipment from the MV-3 central computer are discussed.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: The Telecommun. and Data Acquisition Report; p 1-7
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    National geotechnical centrifuge (1982)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: A high G-ton centrifuge, able to take a 2700 kg (6000 lb) payload up to 300 G, is described. The stability of dams and embankments, the bearing capacity of soil foundations, and the dynamic behavior of foundations due to vibration of machinery are examples of applications. A power rating of 6,000 kW (9,000 hp) was established for the motor. An acceptable maximum speed of 70 rpm was determined. A speed increase with a ratio of 1:3 is discussed. The isolated tension straps, the anti-spreader bar and the flexwall bucket, and safety precautions are also discussed.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Kennedy Space Center The 16th Aerospace Mech. Symp.; p 201-210
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    Room-temperature mercuric iodide spectrometry for low-energy X-rays (1982)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: A discussion of the limits of energy resolution in different energy ranges is given. The energy resolution of a spectrometer is analyzed in terms of the parameters characterizing the crystal, the detector, and the amplification electronics. A high-resolution room-temperature HgI2 spectrometry system was used to measure low-energy X-ray fluorescence spectra. For the MgK-alpha X-ray line the measured resolution was 245 eV (fwhm); the electronic noise linewidth of the system was 225 eV. Alpha-particles were used to excite X-ray fluorescence from low-Z elements separately or in combination. The shape of the photopeaks in the spectra is discussed.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Nuclear Instruments and Methods (ISSN 0167-5087); 193; 1982
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    NIMBUS-ERB instrument study (1982)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Characterization studies were performed on flight spare ERB wide field of view Earth flux sensors. Field of view sensitivity profiles were determined for total energy sensors with and without painted baffles. Similarly, sensors with filter domes were also characterized in terms of field of view. The transient response of sensors with filter domes was determined for both long wave and short wave radiation. Long wave radiation interacts directly with the quartz dome causing undesired responses. While short wave radiation was shown not to interact with the domes, modules as a whole exhibited a secondary response to bursts of short wave radiation indicative of a heating mechanism. How the results of this characterization can or should be applied to the data emanating from these sensors on ERB-6 and 7 is outlined.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA-CR-165922 , NAS 1.26:165922
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  • 87
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    Three-dimensional stylus profilometry (1982)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: The method of three-dimensional stylus profilometry is presented together with a computer-based system for transforming the surface topography of a specimen into an intensity image. Examples are given in which intensity images obtained by stylus profilometry are compared with scanning electron micrographs and two other representations of the stylus data. The comparisons are made for three types of surface irregularities: a discrete feature, a periodic profile surface, and a random profile surface. It is shown that stylus profilometry provides high vertical resolution for low sloped surfaces and thus can be useful in revealing features not easily detectable with other methods.
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  • 88
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    A new surface-streamline flow-visualization technique (1982)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: This paper describes a new surface-streamline flow-visualization technique that is suitable for use in low-speed wind tunnels or other low-speed gas flows. The technique provides a permanent record of ink traces that show surface-streamline direction and shape. The visualization of the endwall surface flow of the horseshoe-vortex system formed around the base of a cylinder by a separating turbulent boundary layer is used as an example. The results of the new technique are compared with those obtained from a conventional flow-visualization technique. Good agreement was found between the two, with the new technique appearing to give more-accurate surface streamlines.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Journal of Fluid Mechanics; 125; Dec. 198
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  • 89
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    Atomic clocks for astrophysical measurements (1982)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: It is noted that recently developed atomic hydrogen masers have achieved stability well into the 10 to the -16th domain for averaging time intervals beyond 1000 sec and that further improvements are in prospect. These devices are highly adaptable for space use in very high precision measurements of angle through Very Long Baseline Interferometry (VLBI) and of range and range-rate through Doppler techniques. Space missions that will use these clocks for measuring the sun's gravity field distribution and for testing gravitation and relativity (a project that will include a search for pulsed low-frequency gravitational waves) are discussed. Estimates are made of system performance capability, and the accuracy capability of relativistic measurements is evaluated in terms of the results from the 1976 NASA/SAO spaceborne clock test of the Einstein Equivalence Principle.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
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  • 90
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    Modeling and a correlation algorithm for spaceborne SAR signals (1982)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: A mathematical model of a spaceborne synthetic aperture radar (SAR) response is presented. Thhe associated SAR system performance, in terms of the resolution capability, is also discussed. The analysis of spaceborne SAR target response indicates that the SAR correlation problem is a two-dimensional one with a linear shift-variant response function. A new digital processing algorithm is proposed here in order to realize an economical digital SAR correlation system. The proposed algorithm treats the two-dimensional correlation by a combination of frequency domain fast correlation in the azimuth dimension and a time-domain convolver type of operation in the range dimension. Finally, digitally correlated SEASAT satellite SAR imagery is used in an exemplary sense to validate the SAR response model and the new digital processing technique developed.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: IEEE Transactions on Aerospace and Electronic Systems; AES-18; Sept
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  • 91
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    A temperature control design for a tapered element oscillating microbalance sensing surface (1982)
    In:  CASI
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    Publication Date: 2019-06-28
    Description: A design study is presented which shows that a tapered element oscillating microbalance can be adapted for temperature control under space application by mating with multistage thermoelectric coolers in such a way that an integral structure evolves. The control of the temperature of the sensing surface can be achieved in a number of ways. An indirect method which uses a measurement of the absorbed power is recommended. The design goals can be met if a relaxation of the power requirement can be considered.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA-CR-169910 , NAS 1.26:169910
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  • 92
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    Computational modeling of multispectral remote sensing systems: Background investigations (1982)
    In:  CASI
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    Publication Date: 2019-06-28
    Description: A computational model of the deterministic and stochastic process of remote sensing has been developed based upon the results of the investigations presented. The model is used in studying concepts for improving worldwide environment and resource monitoring. A review of various atmospheric radiative transfer models is presented as well as details of the selected model. Functional forms for spectral diffuse reflectance with variability introduced are also presented. A cloud detection algorithm and the stochastic nature of remote sensing data with its implications are considered.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA-CR-165974 , NAS 1.26:165974
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  • 93
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    A quantitative applications-oriented evaluation of Thematic Mapper design specifications (1982)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: Simulated Thematic Mapper data sets were created from aircraft Multispectral Scanner data in order to predict the sensitivity of applications-oriented classification results to variations in selected sensor parameters. It was found that band-to-band misregistration as little as 0.3 pixel can have a pronounced effect on the classification of both field-center pixels and pixels associated with edges and small objects in the scene. It was also determined that a significant improvement in classification accuracy could be achieved if the resolution of the thermal band of the Thematic Mapper were comparable to the resolution of its other spectral bands.
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  • 94
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    Evaluation of a wall-flow direction probe for measurements in separated flows (1982)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: The upstream-downstream flow direction intermittency is an important parameter that can quantitatively describe the stages of flow separation. This paper gives an improved design for a wall-flow-direction probe. Intermittency measurements made using this modified probe show agreement within experimental uncertainties with direct measurements made using a LDV, although both the unmodified and modified probe designs produce results that are consistently higher than those for the LDV.
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  • 95
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    Preston tube calibrations and direct force floating element measurements in a two-dimensional turbulent boundary layer (1982)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: Preston tubes provide a convenient means of estimating local wall shear stress. Practical difficulties arise from a lack of calibration data obtained in turbulent boundary layer flows and from the wide choice of calibration equations available mainly from pipe flow calibrations. The results of an experimental study comparing a large number of direct force local wall shear stress measurements in a near-zero pressure gradient two-dimensional turbulent boundary layer flow are presented. The results indicate that there is consistent and excellent agreement between the Patel intermediate calibration formula and the direct force measurements. Typical differences among the direct force measurements and several other proposed calibration equations are also shown.
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  • 96
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    Digital imaging techniques in experimental stress analysis (1982)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: Digital imaging techniques are utilized as a measure of surface displacement components in laser speckle metrology. An image scanner which is interfaced to a computer records and stores in memory the laser speckle patterns of an object in a reference and deformed configuration. Subsets of the deformed images are numerically correlated with the references as a measure of surface displacements. Discrete values are determined around a closed contour for plane problems which then become input into a boundary integral equation method in order to calculate surface traction in the contour. Stresses are then calculated within this boundary. The solution procedure is illustrated by a numerical example of a case of uniform tension.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Optical Engineering; 21; May-June
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    New measurement of the Fano factor of mercuric iodide (1982)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: It is pointed out that mercuric iodide (HgI2) shows great promise as a high-resolution X-ray detector for use in X-ray astronomy. Development of mercuric iodide for astronomical work has required investigation of the temperature dependence of the HgI2 crystal parameters such as leakage current, resolution, and mobility of the charge carriers. The first studies in connection with these investigations have led to a new value of the Fano factor of 0.19 + or - 0.03. The best value previously reported was 0.27 measured at room temperature. The new upper limit of 0.19 for the HgI2 Fano factor was determined by cooling the HgI2 crystal and preamp to -20 C. It is concluded that room-temperature energy resolution of HgI2 is not limited by charge generation statistics but rather by collection efficiency.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Review of Scientific Instruments; 53; May 1982
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  • 98
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    High-resolution imaging with a two-dimensional resistive anode photon counter (1982)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: A method to achieve high spatial resolution readout of individual photoelectron events using microchannel plates and a resistive anode is presented. A clamped pair of microchannel plates is used, followed by a gap and a clamped triplet of microchannel plates in cascade to achieve a high stable electron gain of 3 x 10 to the 7th. The gain allows the position determination of each photoelectron event with a very high signal-to-noise ratio. A model consisting of a windowless vacuum-ultraviolet image sensor is presented to demonstrate 500 x 500 pixel images of 50 micron FWHM over a 25-mm circular field of view. The detector offers sufficient speed, sensitivity and resolution for a variety of applications, and the mount design is compatible with planar, remotely-processed, proximity-focused photocathodes.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Review of Scientific Instruments; 53; May 1982
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  • 99
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    Photogrammetry of the Viking Lander imagery (1982)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: The problem of photogrammetric mapping which uses Viking Lander photography as its basis is solved in two ways: (1) by converting the azimuth and elevation scanning imagery to the equivalent of a frame picture, using computerized rectification; and (2) by interfacing a high-speed, general-purpose computer to the analytical plotter employed, so that all correction computations can be performed in real time during the model-orientation and map-compilation process. Both the efficiency of the Viking Lander cameras and the validity of the rectification method have been established by a series of pre-mission tests which compared the accuracy of terrestrial maps compiled by this method with maps made from aerial photographs. In addition, 1:10-scale topographic maps of Viking Lander sites 1 and 2 having a contour interval of 1.0 cm have been made to test the rectification method.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Photogrammetric Engineering and Remote Sensing; 48; May 1982
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  • 100
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    Optical Studies of model binary miscibility gap system (1982)
    In:  CASI
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    Publication Date: 2019-06-28
    Description: In order to develop a better understanding of separation processes in binary miscibility gap metal alloys, model transparent fluid systems were studied. The system selected was diethylene glycol-ethyl salicylate which has convenient working temperatures (288 to 350 K), low toxicity, and is relatively easy to purify. The system is well characterized with respect to its phase diagram, density, surface and interfacial tensions, viscosity and other pertinent physical properties. Studies of migration of the dispersed phase in a thermal gradient were performed using conventional photomicroscopy. Velocities of the droplets of the dispersed phase were measured and compared to calculated rates which included both Stokes and thermal components. A holographic microscopy system was used to study growth, coalescence, and particle motions. Sequential holograms allowed determination of particle size distribution changes with respect to time and temperature. Holographic microscopy is capable of recording particle densities up to 10 to the 7th power particles/cu cm and is able to resolve particles of the order of 2 to 3 microns in diameter throughout the entire volume of the test cell. The reconstructed hologram produces a wavefront that is identical to the original wavefront as it existed when the hologram was made. The reconstructed wavefront is analyzed using a variety of conventional optical methods.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA-TM-82494 , NAS 1.15:82494
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