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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 253 records · Page 14
All sourcesNASA NTRSDOE OSTI
NASA NTRS1981

Short interval testing of solar cells

A drawback of conventional electrical evaluation procedures regarding solar cells is related to time consuming operations required in the determination of specific parameters, such as the maximum power point, from the plotted curves, and to the transfer of data to a large digital computer for analysis and manipulation. This is especially true when large numbers of cells must be measured. To overcome such drawbacks, a digital short interval tester was designed and constructed. The new tester provides rapid and accurate measurements at constant temperature. The utilization of a light shutter makes it possible to measure up to 200 data points along the I-V curve in less than a second, thus avoiding thermal effects. Because the system is digital, parameters such as the maximum power may be calculated directly from the data.

Saylor, C. R.↗
NASA NTRS1981

A pulse-forming network for particle path visualization

A procedure is described for visualizing nonsteady fluid flow patterns over a wide velocity range using discrete nonluminous particles. The paramount element responsible for this capability is a pulse-forming network with variable inductance that is used to modulate the discharge of a fixed amount of electrical energy through a xenon flashtube. The selectable duration of the resultant light emission functions as a variable shutter so that particle path images of constant length can be recorded. The particles employed as flow markers are hydrogen bubbles that are generated by electrolysis in a water tunnel. Data are presented which document the characteristics of the electrical circuit and establish the relation of particle velocity to both section inductance and film exposure.

Mcalister, K. W.↗
NASA NTRS1982

Voyager spacecraft images of Jupiter and Saturn

The Voyager imaging system is described, noting that it is made up of a narrow-angle and a wide-angle TV camera, each in turn consisting of optics, a filter wheel and shutter assembly, a vidicon tube, and an electronics subsystem. The narrow-angle camera has a focal length of 1500 mm; its field of view is 0.42 deg and its focal ratio is f/8.5. For the wide-angle camera, the focal length is 200 mm, the field of view 3.2 deg, and the focal ratio of f/3.5. Images are exposed by each camera through one of eight filters in the filter wheel on the photoconductive surface of a magnetically focused and deflected vidicon having a diameter of 25 mm. The vidicon storage surface (target) is a selenium-sulfur film having an active area of 11.14 x 11.14 mm; it holds a frame consisting of 800 lines with 800 picture elements per line. Pictures of Jupiter, Saturn, and their moons are presented, with short descriptions given of the area being viewed.

Birnbaum, M. M.↗
NASA NTRS1984

Fluid/Vapor Separator for Variable Flow Rates

Shutter varies gas throughput of porous plug. Variable area exposed on porous plug allows to pass varying rates of vapor flow while blocking flow of liquid helium II from cryogenic bath. Applications in refining operations, industrial chemistry, and steam-powered equipment.

Lee, J. M.↗
NASA NTRS1982

Thematic mapper flight model preshipment review data package. Volume 4: Appendix. Part E: Electronics module data

Tests to verify the as-designed performance of all circuits within the thematic mapper electronics module unit are described. Specifically, the tests involved the evaluation of the scan line corrector driver, shutter drivers function, cal lamp controller function, post amplifier function, command decoder verification unit, and the temperature and actuator controllers function.

Source record↗
NASA NTRS1984

High speed, low cost, LEO-thermal-cycling facility

The design and operations of a low cost, high rate thermal cycling facility designed for LEO conditions is described. Thermal cycling facilities were constructed with various design criteria. Some were designed to duplicate as closely as possible the conditions a cell or module would encounter while in orbit about the Earth. A typical facility to perform this type of cycling was a large vacuum system with liquid nitrogen cooled walls. The cells were heated by an AMO spectrum solar simulator, then a shutter was closed allowing the cells to give up their heat to the cold walls. This system was good at duplicating the orbital conditions but was slow and very costly to operate. Other systems used a gas atmosphere and heated the cells with radiant heat and cooled the cells by moving them into close proximity to a cold plate. The systems greatly increased the cycle times. Other systems moved the heating and cooling atmosphere into and out of the test areas and achieved reasonable cycle rates. All these systems, however, are expensive to operate.

Hart, R. E., Jr.↗
NASA NTRS1984

Thermal Band Characterization of LANDSAT-4 Thematic Mapper

A quick look monitor in the spacecraft control center was used to measure the TM Band 6 shutter background and the 34.7 C internal blackbody signal on over 50 dates. Comparison of relative internal gains between the four channels to prelaunch values showed changes over 9 months of up to 5%, while 512 x 512 subsections of the original 10 daytime scenes showed scene counts that ranged from 135 down to 62. A night scene of the Buffalo area was used to determine channel gain relative to the mean and to discern a systematic along scan pattern in a difference between forward and reverse scan counts of up to 0.5. A corrected digital image was produced and individual gains and offsets were calculated for the four channels. At satellite radiance was determine and noise equivalent temperature difference was calculated. The calibration data and the Buffalo scene, with the corrections and estimates of the atmospheric transmission and radiance, were used to make a temperature estimate for an area of Lake Erie of 21 C to 27 C. Local records of the temperature showed 21 C.

Lansing, J. C.↗
NASA NTRS1983

Identification of active faults in enlarged stereo models of Skylab S-190B photographs

Most of the physiographic indicators of recent movement known to be present along the Indio Hills segment of the San Andreas fault zone can be identified on enlarged Skylab S-190B stereo photographs. These include offset streams, beheaded streams, offset fans, shutter ridges, linear valleys, scarps and vegetation anomalies. Where physiographic indicators of recent movement are present, the S-190B system affords the necessary resolution and stereoscopy for distinguishing activate from inactive faults.

Merifield, P. M.↗
NASA NTRS1984

Simple collimator for use with diamond-anvil cells in a synchrotron beam

A simple double-slit system is described which allows a synchrotron beam to be collimated onto a small sample (approximately 150-micron diameter) in a diamond-anvil cell using remote control. The apparatus can be constructed easily and inexpensively, and allows the shutter positions to be monitored accurately using readily available electronic equipment. A desirable feature of the collimator is the relatively small time needed for adjustment.

Spain, I. L.↗
NASA NTRS1984

Characterization of CNRS Fizeau wedge laser tuner

A fringe detection and measurement system was constructed for use with the CNRS Fizeau wedge laser tuner, consisting of three circuit boards. The first board is a standard Reticon RC-100 B motherboard which is used to provide the timing, video processing, and housekeeping functions required by the Reticon RL-512 G photodiode array used in the system. The sampled and held video signal from the motherboard is processed by a second, custom fabricated circuit board which contains a high speed fringe detection and locating circuit. This board includes a dc level discriminator type fringe detector, a counter circuit to determine fringe center, a pulsed laser triggering circuit, and a control circuit to operate the shutter for the He-Ne reference laser beam. The fringe center information is supplied to the third board, a commercial single board computer, which governs the data collection process and interprets the results.

Source record↗
NASA NTRS1984

Sintered plug flow modulation of a vapor-liquid phase separator for a helium II vessel

Presented is a system for modulation of a superfluid (helium II) flow in a vapor-liquid phase separator, for use in cryogenic storage tanks in future space missions. The system consists of a semicircular mechanically operated shutter, downstream of the separator plug, rotated at 0.1 rpm to control the operational surface area of the separator. The mass flow rate was varied from 10 to 22 mg/s. Pressure gradients across the plug are also discussed.

Frederking, T. H. K.↗
NASA NTRS1985

Postlaunch corrections for Thematic Mapper 5 (TM-5) radiometry in the Thematic Mapper Image Processing System (TIPS)

The paper discusses postlaunch corrections made to the calibration lamp radiance values for band 3 of TM-5 (Thematic Mapper instrument on Landsat-5). It is hypothesized that the low in-orbit temperatures have caused the shutter arm to contract slightly, causing the detectors to view the lamps through different parts of the lens system. Owing to unevenness in the lenses this is introducing an odd-even channel discrepancy in the computed gains, resulting in striped imagery. The process used to compute the new values is presented along with supporting data and the old and new radiance numbers. The new values solve the relative radiometric correction problem of striping. However, the effect on the absolute radiometric correction performance is not quantitatively known.

Singh, A.↗
NASA NTRS1986

Secure Disposal Container for Classified Papers

Meshing steel combs retain papers when container overturned. Comblike shutters installed on hinges near deflectors. If container is upright, combs hang vertically and out of way. When container is tipped or overturned, gravity forces one or both of combs to fall over opening. When this happens, teeth intermesh and container opening covered, preventing its contents from falling out.

Collins, Earl R., Jr.↗
NASA NTRS1985

Which calibration-pulse location method is robust?

The Threshold method, with high threshold and contiguous-block parameter values, was found to be a robust method of locating calibration pulses in the presence of light-leak and shutter-edge pulses within the calibration window. Tests used digitized calibration-window background and light-pulse data from the Landsat-5 Thematic Mapper (TM) instrument, analyzed by special software on an Apple II+ personal computer and on a VAX 11/780 minicomputer.

Gunther, F. J.↗
NASA NTRS1986

A wide bandwidth electrostatic field sensor for lightning research

Data obtained from UHF Radar observation of direct-lightning strikes to the NASA F-106B airplane have indicated that most of the 690 strikes acquired during direct-strike lightning tests were triggered by the aircraft. As an aid in understanding the triggered lightning process, a wide bandwidth electric field measuring system was designed for the F-106B by implementing a clamped-detection signal processing concept originated at the Air Force Cambridge Research Lab in 1953. The detection scheme combines the signals from complementary stator pairs clamped to zero volts at the exact moment when each stator pair is maximally shielded by the rotor, a process that restores the dc level lost by the charge amplifier. The new system was implemented with four shutter-type field mills located at strategic points on the airplane. The bandwidth of the new system was determined in the laboratory to be from dc to over 100 Hz, whereas past designs had upper limits of 10 Hz to 100 Hz. To obtain the undisturbed electric field vector and total aircraft charge, the airborne field mill system is calibrated by using techniques involving results from ground and flight calibrations of the F-106B, laboratory tests of a metallized model, and a finite-difference time-domain electromagnetic computer code.

Zaepfel, K. P.↗
NASA NTRS1988

Optical Alignment Device For Laser Communication

Optical alignment device under development enables continuous tracking and coalignment of two beams of light. Intended primarily for laser-communication station, in which transmitted beam must be aligned with received beam to ensure transmitted beam falls on receiver at other station. Expected to consume less power and be smaller and less complicated than alignment shutter and drive previously used. Prism and filter separate two overlapping collimated light beams of different wavelength or polarization. Coordinates of two beams tracked on charge-coupled device to determine degree of directional misalignment between two beams.

Casey, William L.↗
NASA NTRS1987

Infrared observations of contaminants from Shuttle flight 51-F

A small helium-cooled infrared telescope, IRT, was flown on the Shuttle in July/August 1985. The principal astrophysical objectives were to measure the large scale structure of sources and the background radiation. A cold shutter was incorporated to permit absolute flux measurements. Additionally, the engineering objectives included setting upper limits on the infrared radiation from the local environment. Even though the local background overwhelmed the astrophysical background, astronomical sources were still detectable superimposed on this background radiation. Data are presented covering the spectral range from 2 microns to 120 microns. The spatial, spectral, and temporal variations are described. Based on the spectral character and variability in different wavelength bands, the background radiation does not appear to have a single origin. In this paper, the results on the Shuttle environment are presented.

Koch, D. G.↗
NASA NTRS1989

A wide bandwidth electrostatic field sensor for lightning research

Data obtained from UHF radar observation of direct-lightning strikes to the NASA F-106B aircraft have indicated that most of the 690 strikes acquired during direct-strike lightning tests were triggered by the aircraft. As an aid in understanding the triggered lightning process, a wide bandwidth electric field measuring system was designed for the F-106B by implementing a clamped-detection signal processing concept originated at the Air Force Cambridge Research Lab in 1953. The detection scheme combines the signals from complementary stator pairs clamped to zero bolts at the exact moment when each stator pair is maximally shielded by the rotor, a process that restores the dc level lost by the charge amplifier. The system was implemented with four shutter-type field mills located at strategic points on the aircraft. The bandwidth of the system was determined in the laboratory to be from dc to over 100 Hz, whereas past designs had upper limits of 10 to 100 Hz. To obtain the undisturbed electric field vector and total aircraft charge, the airborne field mill system is calibrated by using techniques involving results from ground and flight calibrations of the F-106B, laboratory tests of a metallized model, and a finite difference time-domain electromagnetic computer code.

Zaepfel, Klaus P.↗