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At least 757 records · Page 42
All sourcesNASA NTRSDOE OSTI
NASA NTRS1975

Some long, rate one-half, binary convolutional codes with an optimum distance profile and the systematic versus nonsystematic code question

A tabulation is given of long systematic and long quick-look-in (QLI) nonsystematic rate R = 1/2 binary convolutional codes with an optimum distance profile (ODP). These codes appear attractive for use with sequential decoders. Simulations for two of the new codes are reported and confirm Massey's conjecture that systematic and non-systematic codes of the same rate yield nearly identical computational and error probability performance with sequential decoding when the number of digits transmitted in the tail of the encoded frame is the same for both codes.

Johannesson, R.↗
NASA NTRS1975

Delta wing flutter based on doublet lattice method in NASTRAN

The subsonic doublet-lattice method (DLM) aeroelastic analysis in NASTRAN was successfully applied to produce subsonic flutter boundary data in parameter space for a large delta wing configuration. Computed flow velocity and flutter frequency values as functions of air density ratio, flow Mach number, and reduced frequency are tabulated. The relevance and the meaning of the calculated results are discussed. Several input-deck problems encountered and overcome are cited with the hope that they may be helpful to NASTRAN Rigid Format 45 users.

Jew, H.↗
NASA NTRS1975

Transfer calibration of the transmission of electron-energy spectrometers

Relative intensities of strong peaks in the Hel photoelectron spectra of N2, CO2, CO, and O2 are tabulated. These data were measured with an electron energy analyzer whose relative transmission was calibrated to an accuracy of + or - 5%. The tables are useful for calibrating the transmission of other analyzers for electron energies below 9 eV. Correction for angular distribution effects is discussed.

Gardner, J. L.↗
NASA NTRS1975

Electrolyte concentration changes during operation of the nickel cadmium cell

The concentration and distribution of aqueous potassium hydroxide (KOH) electrolyte in a sealed nickel cadmium cell is considered. The reactions at both electrodes during charge and discharge involve the production or utilization of hydroxyl ion (OH) or water (H2O) which directly affects concentration. Changes in electrolyte concentration relative to the individual electrode reactions is discussed. Quantitative values are provided for the changes in concentration for 6, 12, and 20 ah cells with accepted quantities of precharge and accepted initial quantity of 31% aqueous KOH. Consideration is given to a more correct equation which includes net changes in hydroxyl concentration in addition to water. Also, expected concentrations of electrolyte in cells in the fully charged, 75% charged, 50% charged, 25% charged and discharged condition are calculated. The expected concentration changes for cells in the accelerated tests are also tabulated and compared with measured values. All calculations are made on the assumption that there are no side reactions. Various properties which depend on KOH concentration are listed. The variables include O2, H2, and Cd(OH)2 solubilities in addition to viscosity and conductivity.

Halpert, G.↗
NASA NTRS1975

Data for NASA's AVSSE 2 experiment: 25-mb sounding data and synoptic charts

This report describes the AVSSE II Experiment and presents tabulated rawinsonde data at 25 mb intervals from the surface to 25 mb for the 23 stations participating in the experiment. Soundings were taken between 1200 GMT, May 6 and 1200 GMT, May 7, 1975. Brief discussions are given on the methods of data processing and accuracy. Synoptic charts prepared from the data are presented, as well as an example of contact data.

Fucik, N. F.↗
NASA NTRS1974

Lunar gravity - Apollo 17

Gravity results are displayed as a band of contours about 60 km wide spanning 140 deg of frontside longitude. The contours traverse Grimaldi, Mare Procellarum, Copernicus, Apennines, Mare Serenitatis, Littrow, and Mare Crisium. Redundant gravity areas previously mapped by Apollos 14, 15, 16, and the Apollo subsatellites are tabulated and show excellent consistency. Modeling of Grimaldi reveals a loading greater than the known mascons and thus makes Grimaldi the smallest known mascon feature. Copernicus' gravity profile is best modeled with a mass defect for the basin and a mass excess for the rim. Mare Serenitatis has an irregular mass distribution with central gravity highs shifted approximately 3 deg in latitude.

Sjogren, W. L.↗
NASA NTRS1974

0.9-18-micron photometry of the 14 CIT objects

Infrared (0.9- to 18-micron) photometric magnitudes are tabulated for all 14 CIT objects as a group. NML Cyg, NML Tau, and IRC + 10216 are also included. Comparisons between the CIT sources and other infrared objects are briefly discussed.

Strecker, D. W.↗
NASA NTRS1974

Column densities of interstellar molecular hydrogen

Equivalent widths of some 50 lines in the 0-0 to 5-0 Lyman bands of H2 are reported in the spectra of 28 stars. Curves of growth are given and column densities for levels from J = 0 to J = 5 are tabulated, with a few values and upper limits for N(6) and N(7), together with values for b, the velocity spread parameter. In three Orion stars and in rho Leo pairs of components are detected, the difference in radial velocity is determined, and column densities are measured or estimated; tentative identifications are made with the components observed by Hobbs (1969) in the Na D-lines. Column densities for HD are given for 13 stars. Upper limits for column densities in the first and second vibrational levels are listed for several stars; the ratio of N(J = 0) in the v double prime = 1 level to that in the ground vibrational level is less than 2.4 x 10 to the minus 8th power in zeta Oph. Values of a rotational excitation temperature for the higher J levels are given for all the stars. Data are presented which show an apparent increase of velocity dispersion with J for a number of stars, as measured both from the curves of growth and from line widths.

Spitzer, L., Jr.↗
NASA NTRS1974

Observations of Jupiter's satellites, 1662-1972

A literature search has yielded nearly 26,000 observations of the satellites of Jupiter, made from 1662 through 1972. The type (photographic; micrometer; eclipse, occultation, transit) and number of observations are tabulated in 5-year increments, and a complete bibliography is cited.

Pierce, D. A.↗
NASA NTRS1975

ERTS applications in state land use planning

The progress made and limitations encountered in using ERTS-1 data for resource management in Ohio is surveyed. Photo-opto-electronic techniques were used with special facility equipment and resolution to 10-30 meters was required to determine strip mine features. Lake Erie's sediment patterns were detected along with flooding conditions, large scale vegetative damage caused by toxic air pollutants was identified, Ohio land use categories were tabulated and thematic map containing forested areas was derived. The experimental findings regarding utility/relevance assessment were ranked in 4 classes for all the applications involved. Preliminary recommendations for operational satellite earth resources survey data requirements are presented and data analysis and product dissemination are proposed to be centralized in conjunction with thermal IR data and an increased resolution.

Pincura, P. G.↗
NASA NTRS1974

A high power TWT power processing system

A power processing system (PPS) is designed for a space-type high power (200W RF) multi-collector traveling-wave tube (TWT). The basic power circuit is presented along with the simplified block diagram and the input, output, and general requirements for the PPS design are tabulated. The paper covers the PPS design as to critical TWT/PPS interface requirements, high voltage cathode/collector supply, high voltage components material, packaging, grounding and isolation, and electrical performance. The use of a single two loop control system for the regulation of cathode and collector voltages is shown to give high efficiency, excellent steady-state and transient performance characteristics, and complete protection for TWT and PPS components under transient conditions.

Farber, B. F.↗
NASA NTRS1974

Use of ERTS-1 imagery in forest inventory

The utility of ERTS-1 imagery when combined with field observations and with aircraft imagery and field observations is evaluated. Satellite imagery consisted of 9-1/2 inch black and white negatives of four multispectral scanner bands taken over Polk County, Tennessee. Aircraft imagery was obtained by a C-130 flying at 23,000 ft over the same area and provided the basis for locating ground plots for field observations. Correspondence between aircraft and satellite imagery was somewhat inaccurate due to seasonal differences in observations and lack of good photogrammetry with the data processing system used. Better correspondence was found between satellite imagery and ground observations. Ways to obtain more accurate data are discussed, and comparisons between aircraft and satellite observations are tabulated.

Rennie, J. C.↗
NASA NTRS1974

Remote sensor evaluation model

A format is presented that enables the specification of a sensor system configuration, given a set of knowledge requirements to be satisfied by an earth observation satellite. This format, in a modified form, may also be used to determine whether or not a knowledge requirement can be satisfied by existing sensors, and to indicate the need for developing new sensors. It can be applied to large sets of knowledge requirements, so that versatile, multipurpose earth observation sensor systems can be developed. Implementation of the model to a combination of Nimbus G&H and ERTS E&F missions is shown as a test of its viability. The findings are extensively tabulated, and they tend to support the method.

Kerne, B.↗
NASA NTRS1975

The interstellar medium near the sun - The line of sight to lambda Scorpii

Copernicus satellite spectrometric observations are used to determine column densities and ionization structure in the local interstellar medium in the line of sight to lambda Sco. Three, or possibly four, regions are identified by physical properties or velocity separations in the UV absorption line profiles, including a region with a temperature near 200,000 K containing O VI lines, one or two H II regions, and an H I region which may also contain S III and C III. Element abundances are tabulated, and abundances in the H I region are shown to have a depletion pattern similar to that for the line of sight to zeta Oph.

York, D. G.↗
NASA NTRS1975

Luminous stars in galactic supernova remnants

It is shown that luminous stars should be expected in the vicinity of supernova remnants. Luminous stars within the maximum optical areas of supernova remnants are tabulated from catalogs, and an excitation parameter is correlated with the spectral classification of such stars when their UV flux excites H II regions to produce nebular thermal bremsstrahlung. The correlations indicate that the presence of a ZAMS star of type 08 to 05 is necessary to produce thermal bremsstrahlung equal to the observed flux density at 1 GHz. Optical components of seven other supernova remnants are discussed, and it is concluded that gross uncertainties in the distance moduli of both stars and supernova remnants prevent any associations from being made.

Johnson, H. M.↗
NASA NTRS1975

An analytic method to account for drag in the Vinti satellite theory

A quadrature algorithm is presented which employs analytical expressions for the variations of satellite orbital elements caused by air drag. The Hamiltonian is formally preserved and the Jacobi constants of the motion are advanced with time through the variational equations. The atmospheric density profile is written as a fitted exponential function of the eccentric anomaly, which adheres to tabulated data at all altitudes and simultaneously reduces the variational equations to definite integrals with closed form evaluations, whose limits are in terms of the eccentric anomaly. Results are given for two intense air drag satellites and indicate that the satellite ephemerides produced by this method in conjunction with the Vinti program are of very high accuracy.

Watson, J. S.↗