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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 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1999

Activity of the 1998 Leonid Shower From the Video Records

Video observations of the Leonid shower aboard two aircraft in the 1998 Leonid multi-instrument aircraft campaign and from ground locations in China are presented. Observing at altitude proved particularly effective, with four times higher rates due to low extinction and low angular velocity at the horizon. The rates, derived from a total of 2500 Leonid meteors, trace at least two distinct dust components. One dominated the night of 1998 November 16/17. This two-day wide component was rich in bright meteors with r = N (m + 1)/N (m) approximately equal 1.5 (s = 1.4) and peaked at an influx of 3.1 +/- 0.4 x 10(exp -12) /sq m.s (for particles of mass < 7 x 10(exp -5) g) at solar longitude lambda(sub 0) approximately equal 234.52 (Eq. J2000). The other more narrow component peaked on 1998 November 17/18 at lambda(sub 0) = 235.31 +/- 0.01. Rates were elevated above the broad component between lambda(sub 0) = 235.15 and 235.40, symmetric around the current node of the parent comet 55P/Tempel-Tuttle, peaking at 5.1 +/- 0.2 x 10(exp -12) /sq m.s. The population index was higher, r = 1.8 +/- 0.1 (s = 1.7), but not as high as in past Leonid storms (r = 3.0). The flux profile of this component has an unusual asymmetric shape, which implies a blend of contributions from at least two different but relatively recent epochs of ejection. The variation of r across the profile might be due to mass-dependent ejection velocities of the narrowest component. High rates of faint meteors occurred only in an isolated five-minute interval at lambda(sub 0) = 235.198, which is likely the result of a single meteoroid breakup in space.

Jenniskens, Peter↗
NASA NTRS1975

Computerized tomography using video recorded fluoroscopic images

A computerized tomographic imaging system is examined which employs video-recorded fluoroscopic images as input data. By hooking the video recorder to a digital computer through a suitable interface, such a system permits very rapid construction of tomograms.

Kak, A. C.↗
NASA NTRS1977

Computerized tomography using video recorded fluoroscopic images

The use of video-recorded fluoroscopic images as input data for digital reconstruction of objects from their projections is examined. The fluoroscopic and the scanning apparatus used for the experiments are of a commercial type already in existence in most hospitals. It is shown that for beams with divergence up to about 15 deg, one can use a convolution algorithm designed for the parallel radiation case with negligible degradation both quantitatively and from a visual quality standpoint. This convolution algorithm is computationally more efficient than either the algebraic techniques or the convolution algorithms for radially diverging data. Results from studies on Lucite phantoms and a freshly sacrificed rat are included.

Kak, A. C.↗
NASA NTRS1966

DSIF FR-900 video recorders

Deep Space Instrumentation Facility FR-900 ROTARY head magnetic tape recorders for acquiring video data from lunar orbiter

MAGNETIC TAPE RECORDER↗
NASA NTRS2011

Characterization of Axial Inducer Cavitation Instabilities via High Speed Video Recordings

Sub-scale water tests were undertaken to assess the viability of utilizing high resolution, high frame-rate digital video recordings of a liquid rocket engine turbopump axial inducer to characterize cavitation instabilities. These high speed video (HSV) images of various cavitation phenomena, including higher order cavitation, rotating cavitation, alternating blade cavitation, and asymmetric cavitation, as well as non-cavitating flows for comparison, were recorded from various orientations through an acrylic tunnel using one and two cameras at digital recording rates ranging from 6,000 to 15,700 frames per second. The physical characteristics of these cavitation forms, including the mechanisms that define the cavitation frequency, were identified. Additionally, these images showed how the cavitation forms changed and transitioned from one type (tip vortex) to another (sheet cavitation) as the inducer boundary conditions (inlet pressures) were changed. Image processing techniques were developed which tracked the formation and collapse of cavitating fluid in a specified target area, both in the temporal and frequency domains, in order to characterize the cavitation instability frequency. The accuracy of the analysis techniques was found to be very dependent on target size for higher order cavitation, but much less so for the other phenomena. Tunnel-mounted piezoelectric, dynamic pressure transducers were present throughout these tests and were used as references in correlating the results obtained by image processing. Results showed good agreement between image processing and dynamic pressure spectral data. The test set-up, test program, and test results including H-Q and suction performance, dynamic environment and cavitation characterization, and image processing techniques and results will be discussed.

Arellano, Patrick↗
NASA NTRS2004

Synchronization of video recording and laser pulses including background light suppression

An apparatus for and a method of triggering a pulsed light source, in particular a laser light source, for predictable capture of the source by video equipment. A frame synchronization signal is derived from the video signal of a camera to trigger the laser and position the resulting laser light pulse in the appropriate field of the video frame and during the opening of the electronic shutter, if such shutter is included in the camera. Positioning of the laser pulse in the proper video field allows, after recording, for the viewing of the laser light image with a video monitor using the pause mode on a standard cassette-type VCR. This invention also allows for fine positioning of the laser pulse to fall within the electronic shutter opening. For cameras with externally controllable electronic shutters, the invention provides for background light suppression by increasing shutter speed during the frame in which the laser light image is captured. This results in the laser light appearing in one frame in which the background scene is suppressed with the laser light being uneffected, while in all other frames, the shutter speed is slower, allowing for the normal recording of the background scene. This invention also allows for arbitrary (manual or external) triggering of the laser with full video synchronization and background light suppression.

Kalshoven, Jr., James E.↗
NASA NTRS1991

Video Recording Of Images In Laser Remote Sensing

Timing technique enables recording of images in laser remote sensing of environment. Timings of laser pulse, shutter, and video frame synchronized. Technique also used in industrial or commercial processes requiring clear sighting of laser beams relative to their surroundings.

Kalshoven, James E., Jr.↗
NASA NTRS1985

Measurement of orbital dynamics of the OAST-1 Solar Array using recorded video images

The OAST-1 Solar Array Experiment was flown on Shuttle mission STS-41D on August 31, 1984 for NASA's Office of Aeronautics and Space Technology. It is pointed out that this was the first flight demonstration of the operation of a large solar array which was designed for multiple deployments and retractions. The array represents also a new class of very lightweight, flexible, low-frequency structures. A program was, therefore, implemented with the aim to study the structural dynamics of the array on the basis of a photogrammetric analysis of data obtained with the existing Shuttle closed circuit television (CCTV) system. The present paper has the objective to describe the experiment and its implementation, taking into account the unique process of analyzing the video data.

Miller, J. B.↗
NASA NTRS1971

Scan converting video tape recorder

A video tape recorder is disclosed of sufficient bandwidth to record monochrome television signals or standard NTSC field sequential color at current European and American standards. The system includes scan conversion means for instantaneous playback at scanning standards different from those at which the recording is being made.

Holt, N. I.↗
NASA NTRS1975

Lightning properties in Florida thunderstorms from video tape records

From video-tape recordings of lightning flashes to ground in convective daytime storms at the NASA Kennedy Space Center, Florida, and near Ocala, Florida, statistical data are presented for the flash-time duration, the number of strokes per flash, the time between all strokes, and the time between strokes having spatially separate channels. A daytime video tape 'photograph' of a stepped leader is reproduced. Finally, statistical data are presented for 13 long horizontal lightning discharges occurring along a line of nocturnal thunderstorms near Gainesville, Florida. These discharges all propagated horizontally near the freezing level (4.5 km) at an apparent average velocity between 5600 and 11,000 m/s for a typical distance of 2 to 3 km. Eleven of the 13 horizontal discharges were preceded by or occurred within 16.7 ms of a glow in the cloud roughly 0.5 km above the horizontal channel.

Brantley, R. D.↗
NASA NTRS2004

Flow visualization and characterization of evaporating liquid drops

An optical system, consisting of drop-reflection image, reflection-refracted shadowgraphy and top-view photography, is used to measure the spreading and instant dynamic contact angle of a volatile-liquid drop on a non-transparent substrate. The drop-reflection image and the shadowgraphy is shown by projecting the images of a collimated laser beam partially reflected by the drop and partially passing through the drop onto a screen while the top view photograph is separately viewed by use of a camera video recorder and monitor. For a transparent liquid on a reflective solid surface, thermocapillary convection in the drop, induced by evaporation, can be viewed nonintrusively, and the drop real-time profile data are synchronously recorded by video recording systems. Experimental results obtained from this technique clearly reveal that evaporation and thermocapillary convection greatly affect the spreading process and the characteristics of dynamic contact angle of the drop.

Chao, David F.↗
NASA NTRS1982

Chemistry of cometary meteoroids from video-tape records of meteor spectra

The chemistry of the cometary meteoroids was studied by closed circuit television observing systems. Vidicon cameras produce basic data on standard video tape and enable the recording of the spectra of faint shower meteors, consequently the chemical study is extended to smaller particles and we have a larger data bank than is available from the more conventional method of recording meteor spectra by photography. The two main problems in using video tape meteor spectrum records are: (1) the video tape recording has a much lower resolution than the photographic technique; (2) video tape is relatively new type of data storage in astronomy and the methods of quantitative photometry have not yet been fully developed in the various fields where video tape is used. The use of the most detailed photographic meteor spectra to calibrate the video tape records and to make positive identification of the more prominent chemical elements appearing in the spectra may solve the low resolution problem. Progress in the development of standard photometric techniques for the analysis of video tape records of meteor spectra is reported.

Millman, P. M.↗
NASA NTRS1988

Development of experimental systems for material sciences under microgravity

As part of the Space Experiment Program of the Society of Japanese Aerospace Companies, three experimental systems (G452, G453, G454) have been developed for materials science studies under microgravity by the NEC Corporation. These systems are to be flown as Get Away Special payloads for studying the feasibility of producing new materials. Together with the experimental modules carrying the hardware specific to the experiment, the three systems all comprise standard subsystems consisting of a power supply, sequence controller, temperature controller, data recorder, and video recorder.

Tanii, Jun↗
NASA NTRS1993

Transient liquid-crystal technique used to produce high-resolution convective heat-transfer-coefficient maps

In this transient technique the preheated isothermal model wall simulates the classic one-dimensional, semi-infinite wall heat transfer conduction problem. By knowing the temperature of the air flowing through the model, the initial temperature of the model wall, and the surface cooling rate measured at any location with time (using the fast-response liquid-crystal patterns recorded on video tape), the heat transfer coefficient can be calculated for the color isothermal pattern produced. Although the test was run transiently, the heat transfer coefficients are for the steady-state case. The upstream thermal boundary condition was considered to be isothermal. This transient liquid-crystal heat-transfer technique was used in a transient air tunnel in which a square-inlet, 3-to-1 exit transition duct was placed. The duct was preheated prior to allowing room temperature air to be suddenly drawn through it. The resulting isothermal contours on the duct surfaces were revealed using a surface coating of thermochromic liquid crystals that display distinctive colors at particular temperatures. A video record was made of the temperature and time data for all points on the duct surfaces during each test. The duct surfaces were uniformly heated using two heating systems: the first was an automatic temperature-controlled heater blanket completely surrounding the test duct like an oven, and the second was an internal hot-air loop through the inside of the test duct. The hot-air loop path was confined inside the test duct by insulated heat dams located at the inlet and exit ends of the test duct. A recirculating fan moved hot air into the duct inlet, through the duct, out of the duct exit, through the oven, and back to the duct inlet. The temperature nonuniformity of the test duct model wall was held very small. Test results are reported for two inlet Reynolds numbers of 200,000 and 1,150,000 (based on the square-inlet hydraulic diameter) and two free-stream turbulence intensities of about 1 percent, which is typical of wind tunnels, and up to 20 percent (using a grid), which is typical of real engine conditions.

Hippensteele, Steven A.↗
NASA NTRS2001

Flow Visualization in Evaporating Liquid Drops and Measurement of Dynamic Contact Angles and Spreading Rate

A new hybrid optical system, consisting of reflection-refracted shadowgraphy and top-view photography, is used to visualize flow phenomena and simultaneously measure the spreading and instant dynamic contact angle in a volatile-liquid drop on a nontransparent substrate. Thermocapillary convection in the drop, induced by evaporation, and the drop real-time profile data are synchronously recorded by video recording systems. Experimental results obtained from this unique technique clearly reveal that thermocapillary convection strongly affects the spreading process and the characteristics of dynamic contact angle of the drop. Comprehensive information of a sessile drop, including the local contact angle along the periphery, the instability of the three-phase contact line, and the deformation of the drop shape is obtained and analyzed.

Zhang, Neng-Li↗
NASA NTRS1984

Status Panel For Video Cassette Recorders

Central array of light-emitting diodes displays status of 30 video cassette recorders (VCR's) monitoring integrated testing of Space Shuttle. Remote status panel linked to VCR's by one 37-conductor cable. Transistor/ transistor logic chips in interface circuit allow LED array to function without drawing power from VCR control circuits.

Talley, G. L., Jr.↗