Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “DE”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 775 records · Page 43
All sourcesNASA NTRSDOE OSTI
NASA NTRS1981

The CCN counter of the IOPG of Puy de Dome: Main characterisics and results of measurements

In performing the data analysis of the measurements achieved during the Workshop with the device, a global approach was preferred rather than an individual analysis, in order to illustrate some main characteristics in the behavior of the device with respect to a mean behavior resulting from a general survey of all the equipments involved in each experiment. The device tends generally to overestimate the CCN concentrations measured near the high supersaturations and sometimes underestimates the concentrations close to 0.1% or 0.2% of supersaturation. Despite the fact that it belongs to a type of static diffusion chamber, it shows, however, similar spectra to those obtained with other types of chambers (continuous flow diffusion chamber and haze chamber).

Serpolay, R.↗
NASA NTRS1981

Study project of intrusive rocks: States of Espirito Santo and Rio de Janeiro, south and east of Minas Gerais and southeast of the state of Sao Paulo

The feasibility of mapping intrusive rocks in polycyclic and polymetamorphic areas using the logic method for photointerpretation of LANDSAT and radar imagery was investigated. The resolution, scale and spectral characteristics of the imagery were considered. Spectral characteristics of the intrusive rock units mapped using image 100 were investigated. It was determined that identification of acidic and basic intrusive bodies and determination of their relationships with principal structural directions using the logic method was feasible. Tectonic compartments were subdivided into units according to their predominant lithographic types, ignoring stratigraphy. The principal directions of various foliations, faults, megafolds, and fractural systems were defined. Delineation of the boundaries of intrusive bodies mapped using the spectral characteristics of Image 100 imagery ws determined to be more accurate than visual analysis. A 1:500,000 scale map of intrusions in the areas studied was generated.

Dejesusparada, N.↗
NASA NTRS1982

Global pictures of the ozone field from high altitudes from DE-I

Detailed synoptic views of the column ozone field can be obtained by the Spin-Scan Ozone Imager (SOI) (Keating et al., 1981) aboard the Dynamics Explorer I satellite. The eccentric polar orbit with an apogee altitude of 23,000 km allows high resolution global-scale images to be obtained within 12 minutes, and allows regions to be viewed for long periods of time. At perigee, a pixel size of nadir measurements of 3 km is possible, and measurements are determined using the backscattered ultraviolet technique. A wavelength measurement of 317.5 nm is used as there are limitations in filter locations and it allows comparison with Nimbus 7 SBUV/TOMS data. Consideration of the reflectivities of this data aids in checking the SOI data reduction algorithm. SOI data show short-term (less than one day) variations in the observed ozone field, and a negative correlation (greater than 0.9) between ozone and tropopause heights. It is expected, due to this correlation, that SOI data will aid in understanding the time evolution of dynamics near the tropopause.

Keating, G. M.↗
NASA NTRS1982

The DE magnetometer preprocessor users guide

A users guide for the Dynamics Explorer magnetometer preprocessor computer program is provided. This program is written in Xerox Extended FORTRAN IV and is used to process telemetry data in order to provide data files for use in analysis programs. This preprocessor is designed to operate on the Sigma 9 and the IBM 4341.

Salter, L. M.↗
NASA NTRS1983

Optical effects of spacecraft-environment interaction Spectrometric observations by the DE-B satellite

Data from the Fabry-Perot interferometer on board the Dynamics Explorer-B satellite is used to show that the contaminant glow observed by Yee and Abreu at 7320A on the AE satellites is produced by emission lines of one or more species. A comparison is made of the contaminant spectrum near 7320A with the nightglow OH spectrum measured below 155km. Evidence is presented to the effect that OH might be one of the metastable species producing the glow.

Abreu, V. J.↗
NASA NTRS1983

Polar cap electron densities from DE 1 plasma wave observations

Electric-field-spectum measurements from the plasma-wave instrument on the Dynamics Explorer 1 spacecraft are used to study the local electron density at high altitudes in the northern polar-cap region. The electron density is determined from the upper cutoff of whistler-mode radiation at the electron plasma frequency. Median density values over the polar cap at L greater than 10 are found to vary from 35.2 + or - 8.5 cu cm at 2.1 earth radii to 0.99 + or - 0.51 cu cm at 4.66 earth radii. The steady-state radial-outflow model is examined for consistency with the observed density profile. A power-law fit to the radial variation of the electron density yields an exponent of - 3.85 + or - 0.32, which for the radial-outflow model implies a flow velocity increasing nearly linearly with incresing radial distance. Comparison of the observed electron densities with theoretical polar-wind densities yields consistent results up to 2.8 earth radii. A comparison of the observed electron densities with low-altitude density profiles from the Alouette II and ISIS 1 spacecraft illustrates transitions in the slope of the profile at 1.16 earth radii and between 1.55 and 2.0 earth radii. The changes in the density profile suggest that changes occur in the basic radial-transport processes at these altitudes.

Persoon, A. M.↗
NASA NTRS1985

Cherenkov-dE/dx-range measurements on cosmic ray iron group nuclei

A balloon experiment which combined a large area plastic detector unit with electronic dE/dx-C data is presented. The correlation of the electronic data with the range data of the plastic detector stack was achieved by rotating plastic detector disks which provided in this way the passive plastic detector with an incorporated time determination. The constant flux of cosmic ray particles with charge Z greater than two was used to gauge the time resolving system. Stopping cosmic ray iron group nuclei in the energy range 400 to 700 MeV/nuc are identified using their electronic scintillator and Cherenkov signals and their etch conelengths and range data. The precise knowledge of the particle's trajectory proposes refined pathlength corrections to the electronic data.

Sermund, G.↗
NASA NTRS1985

Enhanced ion outflows measured by the DE 1 high altitude plasma instrument in the dayside plasmasphere during the recovery phase

Ion flow velocities both parallel and perpendicular to the magnetic field, and including the effects of spacecraft charging and spacecraft velocity, have been measured during the recovery phase of two large magnetic storms on October 14 and 21 of 1981. These measurements were made both inside and outside the plasmasphere and indicate unreported yet substantial outflows of ions within the dayside plasmasphere (October 14). Combined data from instruments on board the Dynamics Explorer satellite, including the high altitude plasma instrument, the energetic ion composition spectrometer, the retarding ion mass spectrometer, and the plasma wave instrument, indicate that these ions are most likely dominantly O(+) at energies at least as low as 5 eV. The nightside pass (October 21), which occurred during the recovery phase of a similar storm, showed no plasmaspheric outflows. The results indicate that a large contribution to the outflux into the dayside plasmasphere during the recovery period is due to E greater than 5 eV ions.

Menietti, J. D.↗
NASA NTRS1985

DE 1 observations of Siple transmitter signals and associated sidebands

Initial results from an active wave injection experiment aimed at studying coherent VLF wave propagation and wave-particle interactions in the magnetosphere are presented. The VLF signals were injected from a transmitting facility at Siple Station, Antarctica, and were received on the high-altitude, polar-orbiting Dynamics Explorer 1 satellite. Data received by the satellite are described and measurements of the propagation delay, signal amplitude, and in situ electron densities are discussed. Ray propagation paths to the satellite for two days are discussed, and sidebands associated with Siple signals observed on one of the days are presented.

Rastani, K.↗
NASA NTRS1985

Electro-impulse de-icing of a turbofan engine inlet

The application of electromagnetic impulse deicing (EIDI) systems to turbofan engine inlets on business aircraft has been investigated experimentally. The tests were performed in the Icing Research Tunnel at NASA's Lewis Research Center. The deicing system testbed was a Falcon Fanjet 20 engine nacelle. The effectiveness of various deicing coil configurations and mount designs were compared, and design parameters were developed specifically for EIDI systems in turbofan engines. Flight tests were also carried out at altitudes in the range 3000-6000 ft corresponding to a temperature range of -3 to -8 C. It is shown that the ice particles removed from the engine inlet by the deicing system were small enough for the engine to ingest. Tentative design specifications are given with respect to the optimum coil configuration, and operating power of a EIDI production candidate.

Zumwalt, G. W.↗
NASA NTRS1985

Energetic auroral and polar ion outflow at DE 1 altitudes Magnitude, composition, magnetic activity dependence, and long-term variations

Data acquired from the Dynamics Explorer I Energetic Ion Composition Spectrometer in the period from September 1981 to May 1984 are used to determine the magnitude of the terrestrial ion outflow in the 0.01-17 keV/el range. The data are also employed to investigate the mass composition and topology (local time and invariant latitude distributions) of the ion outflow, as well as the outflow's magnetic activity dependence and long-term variation. The relative importance of auroral versus polar cap upflowing ions as a source of energetic plasma for various parts of the magnetosphere is examined.

Yau, A. W.↗
NASA NTRS1985

Estimation of particle size based on LDV measurements in a de-accelerating flow field

The accuracy of velocity measurements made with a laser velocimeter is strongly dependent upon the response of the seeding particles to the dynamics of the flow field. The smaller the particle the better the response to flow fluctuations and gradients and therefore the more accurate velocity measurement. In direct conflict is the requirement of light scattering efficiency to obtain signals with the laser velocimeter which, in general, is better as the particle size is increased. In low speed flow fields these two requirements on particle size overlap and accurate measurements may be obtained. However in high speed flows, where the velocity gradients may be severe, very small particles are required to maintain sufficient dynamic response characteristics to follow the flow. Therefore if velocity measurements are to be made in these flows, the laser velocimeter must be designed with sufficient sensitivity to obtain signals from these small particles. An insitu determination of the size distribution of kaolin particles (Al2O3, .2 + or - SiO2 . 2H2O) in the 16-foot Transonic Tunnel and the sensitivity characteristics of the laser velocimeter system is described.

Meyers, J. F.↗
NASA NTRS1985

AE and DE mass spectrometer observations relevant to the shuttle glow

Recent work suggested that NO2 may be responsible for the observed continuum glow near surfaces of the space shuttle. The observations of atomic nitrogen (N) are reported at shuttle altitudes using mass spectrometers, giving special attention to the surface reactions of N relevant to the production of NO2 on spacecraft surfaces. Data from two semi-open sources mass spectrometers, the OSS instruments on the Atmosphere Explorer-C and -D satellites, and the closed source Neutral Atmospheric Composition Spectrometer (NACS) on the Dynamic Explorer-2 satellite are presented to show the similar behavior of NO in each case and the contrasting behavior of NO2. Although signals of NO and NO2 are highly dependent on surface temperature and surface composition, it appears that direct exposure of ion source surfaces to rammed gas is a necessary condition for the production of large amounts of NO2. Evidence that elevated surface temperatures can significantly reduce the production of NO2, likely by causing more rapid desorption of NO from these surfaces, is presented.

Engebretson, M. J.↗