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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 847 records · Page 47
All sourcesNASA NTRSDOE OSTI
NASA NTRS1984

A radio study of the flat spectrum component in CTB 80

Polarization data obtained from high resolution radio observations of the compact, flat spectrum core of CTB 80 allow the extraction of information on the magnetic field and thermal plasma. The magnetic field direction projected onto the plane of the sky that is derived from the average rotation measure reveals a component that runs tangentially along the southern and western periphery of the radio plateau. The thermal density suggested by the depolarization rate is sufficient, if the plasma has a temperature of several million deg, to account for the X-ray emission detected by the Einstein Observatory. Attention is given to the possible nature of a small scale feature near the edge of the radio plateau, which agrees in position with the brightest radio peak.

Strom, R. G.↗
NASA NTRS1985

Imaging spectrometry for earth remote sensing

Initial results of the novel remote earth sensing technique of imaging spectrometry, which is technically feasible from both spacecraft and aircraft platforms, indicate that the direct identification of surface materials on a picture-element basis is possible through proper sampling of absorption features in the reflectance spectrum. Sensors of this type are able to acquire images simultaneously in 100-200 contiguous spectral bands. Computerized data reduction and storage techniques are available for the large data sets thus generated, and novel analytic techniques are under development to maximize information content extraction.

Goetz, A. F. H.↗
NASA NTRS1985

Research and technology, fiscal year 1985

Capabilities in spacecraft subsystems, sensors, space communications and navigation, the acquisition of data from space missions and the extraction of information from that data were reviewed. The use of satellite data in the study of the Earth's atmosphere and climate, the dynamics of its crust and the monitoring of land and water resources were examined. A review of NASA flight projects for 1985 was presented.

Source record↗
NASA NTRS1985

Simulation and modeling of homogeneous, compressed turbulence

Low Reynolds number homogeneous turbulence undergoing low Mach number isotropic and one-dimensional compression was simulated by numerically solving the Navier-Stokes equations. The numerical simulations were performed on a CYBER 205 computer using a 64 x 64 x 64 mesh. A spectral method was used for spatial differencing and the second-order Runge-Kutta method for time advancement. A variety of statistical information was extracted from the computed flow fields. These include three-dimensional energy and dissipation spectra, two-point velocity correlations, one-dimensional energy spectra, turbulent kinetic energy and its dissipation rate, integral length scales, Taylor microscales, and Kolmogorov length scale. Results from the simulated flow fields were used to test one-point closure, two-equation models. A new one-point-closure, three-equation turbulence model which accounts for the effect of compression is proposed. The new model accurately calculates four types of flows (isotropic decay, isotropic compression, one-dimensional compression, and axisymmetric expansion flows) for a wide range of strain rates.

Wu, C. T.↗
NASA NTRS1985

A review and analysis of boundary layer transition data for turbine application

A symposium on transition in turbines was held at the NASA Lewis Research Center. One recommendation of the working groups was the collection of existing transition data to provide standard cases against which models could be tested. A number of data sets from the open literature that include heat transfer data in apparently transitional boundary layers, with particular application to the turbine environment, were reviewed and analyzed to extract transition information from the heat transfer data. The data sets reviewed cover a wide range of flow conditions, from low speed, flat plate tests to full scale turbine airfoils operating at simulated turbine engine conditions. The results indicate that free stream turbulence and pressure gradient have strong, and opposite, effects on the location of the start of transition and on the length of the transition zone.

Gaugler, R. E.↗
NASA NTRS1986

A combined Raman lidar for low tropospheric studies

One of the main goals of laser sensing of the atmosphere was the development of techniques and facilities for remote determination of atmospheric meteorological and optical parameters. Of lidar techniques known at present the Raman-lidar technique occupies a specific place. On the one hand Raman lidar returns due to scattering on different molecular species are very simple for interpretation and for extracting the information on the atmospheric parameters sought, but, on the other hand, the performance of these techniques in a lidar facility is overburdened with some serious technical difficulties due to extremely low cross sections of Raman effect. Some results of investigations into this problem is presented which enables the construction of a combined Raman lidar capable of acquiring simultaneously the profiles of atmospheric temperature, humidity, and some optical characteristics in the ground atmospheric layer up to 1 km height. The operation of this system is briefly discussed.

Arshinov, Y. F.↗
NASA NTRS1986

Quantitative Schlieren analysis applied to holograms of crystals grown on Spacelab 3

In order to extract additional information about crystals grown in the microgravity environment of Spacelab, a quantitative schlieren analysis technique was developed for use in a Holography Ground System of the Fluid Experiment System. Utilizing the Unidex position controller, it was possible to measure deviation angles produced by refractive index gradients of 0.5 milliradians. Additionally, refractive index gradient maps for any recorded time during the crystal growth were drawn and used to create solute concentration maps for the environment around the crystal. The technique was applied to flight holograms of Cell 204 of the Fluid Experiment System that were recorded during the Spacelab 3 mission on STS 51B. A triglycine sulfate crystal was grown under isothermal conditions in the cell and the data gathered with the quantitative schlieren analysis technique is consistent with a diffusion limited growth process.

Brooks, Howard L.↗
NASA NTRS1987

The large Type 4 radio burst event of 24 April 1985 interpreted by dynamic spectral recordings and associated recordings

The Active Region 4647 showed a sudden increase in spot area on 23 April 1985 as well as an appearance of the D magneic configuration. During STIP interval XVII numerous subflares occurred in this region but only one very large event which exhibited all signatures of a classical p-event, well separated in time from other large events. The dynamic spectrum was observed at Bleien, Ondrejov, and Weissenau. The onset of radiation at m- and dm-waves is impulsive, and at dm-waves the preceeding dm continuum rises gradually. The absolute fluxes show very high readings of some 10 to the 4th power SFU at m-waves and some 5 x 10 to the 3d power at cm waves. High energy particles were observed about a day later by IMP 8. A Forbush decrease was seen on the neutron monitors but there was no GLE. The GOES X-ray flux monitors showed a gradual rise to high fluxes and a slow decrease over several hours. This information was extracted from Gdata but also from numerous letters from other observers and interpreters. More detailed data on the event and on the concomitant active region are to be presented.

Urbarz, H. W.↗
NASA NTRS1987

Planetary satellites

Spectrophotometric observations of the atmosphereless planetary satellites obtained with the IUE since its launch in 1978 are reviewed. The value of IUE data in complementing the images obtained by planetary probes is indicated; the techniques used to interpret IUE images of the satellites and extract textural information are discussed; and data on the Gallilean satellites of Jupiter and the satellites of Saturn are presented in extensive tables and graphs and characterized in detail. Consideration is given to the broadband geometric albedos, the orbital phase curves, hemispherical spectral asymmetries, spectral orbital phase variations, and the prospects for further observations with the Space Telescope and other earth-orbiting platforms.

Nelson, Robert M.↗
NASA NTRS1988

Cartographic feature extraction with integrated SIR-B and Landsat TM images

A digital cartographic multisensor image database of excellent geometry and improved resolution was created by registering SIR-B images to a rectified Landsat TM reference image and applying intensity-hue-saturation enhancement techniques. When evaluated against geodetic control, RMSE(XY) values of approximately + or - 20 m were noted for the composite SIR-B/TM images. The completeness of cartographic features extracted from the composite images exceeded those obtained from separate SIR-B and TM image data sets by approximately 10 and 25 percent, respectively, indicating that the composite images may prove suitable for planimetric mapping at a scale of 1:100,000 or smaller. At present, the most effective method for extracting cartographic information involves digitizing features directly from the image processing display screen.

Welch, R.↗
NASA NTRS1988

Radiometric performance of AVIRIS: Assessment for an arid region geologic target

Data from several AVIRIS flight lines were examined to assess instrument stability and response. Both scene and in-flight calibration data were analyzed statistically. The data clearly indicates that, although the instrument output was noisy and unstable at the time of the data acquisition, valuable spectral signatures can still be extracted and analyzed. Some first order calibration corrections can be performed by forcing internal consistency within the data. AVIRIS data are delivered in band-interleaved-by-line format, but high efficiency routines were developed which access the data as either image or spectral planes and enable effective statistical and visual examination of both AVIRIS scenes and ancillary files. Two methods were used to extract spectral information from segment 4 of the Kelso Dunes flight. Both successfully identified at least three distinct spectral signatures, but neither has positively identified a specific material.

Kieffer, Hugh H.↗
NASA NTRS1989

Querying databases of trajectories of differential equations: Data structures for trajectories

One approach to qualitative reasoning about dynamical systems is to extract qualitative information by searching or making queries on databases containing very large numbers of trajectories. The efficiency of such queries depends crucially upon finding an appropriate data structure for trajectories of dynamical systems. Suppose that a large number of parameterized trajectories gamma of a dynamical system evolving in R sup N are stored in a database. Let Eta is contained in set R sup N denote a parameterized path in Euclidean Space, and let the Euclidean Norm denote a norm on the space of paths. A data structure is defined to represent trajectories of dynamical systems, and an algorithm is sketched which answers queries.

Grossman, Robert↗
NASA NTRS1988

Knowledge-based network operations

An expert system for enhancing the operability of the ground communication element of the Jet Propulsion Laboratory's Deep Space Network is described. The system performs network fault management, configuration management, and performance management in real time. Extracted management information serves as input to the expert system and is used to update a management information data base. The monitor and control activities involve dividing software for each processor into layers which are each modeled as a finite state machine.

Wu, Chuan-Lin↗
NASA NTRS1988

ExpertVision - A video-based non-contact system for motion measurement

A system known as ExpertVision for obtaining noncontact kinematic measurements using standard video signals is described. In the system, a video processor extracts edge information from video images using a proprietary thresholding technique. Images can be examined in real time at up to 200 fields/s, and as many as four synchronized inputs can be treated simultaneously by buffering the edge coordinates for each view in dedicated RAM memory. Mechanical applications for ExpertVision include the study of simple impacts, ballistics, wing flutter, the kinematics of helicopter rotor blades, and fluid and gas flow problems.

Walton, James S.↗
NASA NTRS1990

Pressure Gauges Monitor Leakage Past Seals

Method devised to measure leakage of gas past each of two sets of primary and secondary seals into common volume from which aggregate flow measured. Although method applicable only to specific combination of flow configuration and thermal conditions, it serves as example of more general approach involving use of statistical analysis to extract additional information from measurements.

Smith, Steven A.↗
NASA NTRS1989

On the isotope analysis of cometary dust

It is thought that comets are an intimate mixture of ices and sub-micron to pebble sized silicates. Based on experience with carbonaceous chrondrites, part of the smallest grains are expected to be primary condensates carrying the unadulterated isotopic signature of their place of origin. In order to extract this information a grain-by-grain analysis will be necessary.

Begemann, Friedrich↗
NASA NTRS1989

Remote sensing of foliar chemistry

Remotely sensed data are being used to estimate foliar chemical content. This paper reviews how stepwise multiple regression and deconvolution have been used to extract chemical information from foliar spectra, and concludes that both methods are useful, but neither is ideal. It is recommended that the focus of research be modeling in the long term and experimentation in the short term. Long-term research should increase our understanding of the interaction between radiation and foliar chemistry so that the focus of research can move from leaf model to canopy model to field experiment. Short-term research should aim to design experiments in which remotely sensed data are used to generate unambiguous and accurate estimates of foliar chemical content.

Curran, Paul J.↗
NASA NTRS1990

A spherical harmonics method for asteroid pole determination

A new and general method is presented for determining pole orientations of unresolved solar system bodies that exhibit brightness variation with rotation. The accuracy of the method is limited only by the number of available apparitions, which imposes the degree where the Legendre expansion must be truncated. It is shown that power spectra of lightcurves provide enough information to extract pole coordinates from the data, independent of body shape and albedo variegation. The method has been tested using several computer-generated synthetic light-curves, and the accuracy is found to be about 5 deg in both the longitude and latitude of the pole, which is considerably better than that obtained from the standard triaxial ellipsoid model. Finally, the new spherical harmonics method has been applied to six well-observed asteroids: 16 Psyche, 22 Kalliope, 39 Laetitia, 44 Nysa, 45 Eugenia, and 349 Dembowska.

Lumme, K.↗