Search NASA⌕ Search

SEARCH · Search NASA

Results for “POSITIONING”

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 289 records · Page 16
All sourcesNASA NTRSDOE OSTI
NASA NTRS1975

Acoustic field positioning for containerless processing

The noncontact positioning of materials in a space processing chamber is accomplished using a new type of acoustic levitator. Liquid and solid materials are positioned using a single source of sound. Fine control of position may be obtained by motion of an acoustical reflector. The electrical power required is usually less than 100 watts. The system operates satisfactorily at high and low temperatures and is adaptable as an 'add-on' feature to existing space experiments. Containerless melting and solidification can be performed and a freely suspended liquid can be shaped to the contour of the sound field. Experiments are described in which aluminum, glass and plastic materials are melted and solidified in the containerless state. The system has applications to containerless crystal growth, melting and related processes.

Whymark, R. R.↗
NASA NTRS1977

Comparison of susceptibility to motion sickness during rotation at 30 rpm in the earth-horizontal, 10 deg head-up, and 10 deg head-down positions

Normal persons rotated about an earth-horizontal axis vary in their susceptibility to motion sickness. An experimental study was conducted to measure intraindividual differences in susceptibility in 12 subjects when rotated 10 deg head up and 10 deg head down as well as in the horizontal position. Subjects assumed the test-position 60 min prior to rotation, thus providing an opportunity for translocation of body fluids. Physiological and psychological measurements were conducted throughout the experiment. There were no intraindividual differences in susceptibility to motion sickness in the three positions tested, although there were significant differences in vital capacity, demonstrating the expected fluid shifts. It was concluded that, in the sample of subjects tested, short-term effects of fluid shifts greater than those that would be manifested in zero gravity had no definite effect on motion sickness susceptibility.

Graybiel, A.↗
NASA NTRS1977

Experiments for improved positioning by means of integrated Doppler satellite observations and the NNSS broadcast ephemeris

An effort to improve station position recovery using broadcast ephemeris in Doppler data reduction was studied. A comparison of precise and broadcast ephemerides, treating the former as the standard, yielded information about the state disturbance that can be associated with the broadcast ephemeris. Statistical information about the state disturbance was used with current observational data for improved position recovery. The rank deficiency problem encountered in the short arc geodetic adjustment procedure was analysed and it was deduced that the fundamental rank deficiency is six, scale information being derivable from the wavelength of transmission. Coordinate differences between stations coobserving a pass are estimable. The uncertainty of the broadcast ephemeris, now in the WGS72 system, was assessed. It was conservatively estimated that its positional uncertainty may vary between 19 to 26 m in-track, 15 to 20 m cross-track and 9 to 10 m in radial directions depending on the incidence of the epoch of observations in the interinjection period.

Arur, M. G.↗
NASA NTRS1978

On Nth roots of positive operators

A bounded operator A on a Hilbert space H was positive. These operators were symmetric, and as such constitute a natural generalization of nonnegative real diagonal matrices. The following result is thus both well known and not surprising: A positive operator has a unique positive square root (under operator composition).

Brown, D. R.↗
NASA NTRS1978

Station position results using concentrated C-band tracking of GEOS-3

Station positions for the GEOS 3 C Band tracking network were estimated using C Band and laser data taken during a two-week concentrated tracking period. The C Band stations are located primarily in the continental United States and on Western Atlantic islands. The network, however, included stations in Hawaii, in West Germany, and on Kwajalein atoll. Estimated accuracies for the recovered positions are 2 m for the continental U. S. and Atlantic sites, 5 m for Hawaii, and 10 m for Kwajalein. The dominant contributor to these uncertainties is geopotential model error. Thus, the C Band/laser data set could be used for more accurate center-of-mass positioning of a continental network of stations.

Krabill, W. B.↗
NASA NTRS1978

Positions of galactic X-ray sources - l/II/ between 320 and 340 deg

The precise (20-40 sec) positions of seven X-ray sources in the celestial region corresponding to the galactic longitude range from 320 to 340 deg are reported. The sources include a recurrent transient X-ray source (MX1608-52) and a source 2S1553-542 coincident with a gamma-ray source within the given errors of position. The positions reported reduce the previously reported areas of the error region for six of the sources by factors ranging from 10 to 100. The presented results add confidence to the proposed radio candidates for 4U1624-49 and 4U1642-45 considered by Sanduleak and Dolan (1974) and Seaquist (1977).

Apparao, K. M. V.↗
NASA NTRS1977

The spectrum and position of solar noise storms at decameter wavelengths

Decametric storm radiation during the period July-August 1970 has been observed simultaneously with a high sensitivity spectrograph at Arecibo Observatory and with the log-periodic, swept-frequency array of the Clark Lake Radio Observatory. The observations complement each other; different types of fine structure emissions can be easily identified on the spectrograph records and their position can be determined from the swept-frequency recordings. The relative positions of the different emissions which have been observed during the storms are studied. Four distinct sources appear to be present. The continuum emission, the type I bursts and the flare-related type III's are all emitted at different locations. The storm type III bursts, type IIIb's and drift pairs overlap in position, but appear at different locations than the previously mentioned sources.

De La Noe, J.↗
NASA NTRS1978

Measurements of X-ray source positions by the scanning modulation collimator on HEAO 1

This paper reports preliminary results on the positions of X-ray sources obtained with the modulation collimator on the first NASA High Energy Astronomy Observatory, HEAO 1. Calibration on Sco X-1 establishes the experiment capabilities to be within 7 sec as limited by aspect errors. For the reported X-ray sources certain ambiguities in their positions are resolved and the previous optical identifications of four sources are confirmed, two of which are X-ray bursters and one of which is the black hole candidate Cir X-1. An accurate position for a new transient source is also presented.

Gursky, H.↗
NASA NTRS1979

The characteristics of a lift cruise fan V/STOL configuration in near proximity to a small deck with finite edge positions

Two V/STOL model configurations utilizing lift-cruise-fans for the propulsion system have been tested in the presence of a small landing platform with finite deck edge positions. Results and analysis of these tests are presented. The model was tested at both static (zero velocity) and forward speed conditions with several heights and deck edge positions. Configurations utilizing three fans and four fans were investigated. Incremental forces and moments induced by the various deck edge positions are analyzed as relating to the model height above the ground and the thrust velocity relationships. The test and analysis show the induced forces to be relatively unaffected by deck edge.

Stewart, V. R.↗
NASA NTRS1980

Blood filling and flow in lungs during change in body position in space

In the horizontal position (supine and lateral), in the upright position (head up and head down) and during change of the cat body position in space, quantitative responses of regional blood volume and blood flow in the lungs (ml/100 cu cm) revealed presence of the gradient in the gravitation direction. Blood volume and blood flow of different lung portions changed qualitatively and quantitatively in different ways. These changes occurred only in the direction producing the equality of regional hydrostatical and hemodynamic loads in the lungs at either horizontal level.

Pogodin, A. S.↗
NASA NTRS1979

Experiments for improved positioning by means of integrated Doppler satellite observations and the NNSS broadcast ephemeris

A study to improve position determination using broadcast ephemeris in Doppler data reduction is presented. The uncertainty of the broadcast ephemeris was assessed, and sample autocovariances were computed for acceleration, velocity, and position considering the state disturbance as a signal. An experiment was made in which three stations coobserved 12 passes, and the removal of the radial bias resulted in a chord distance which was in better agreement with the ground survey. In the second experiment, the station positions of the first test simulated the range observations, and the autocovariance function of the acceleration signal in the Cartesian coordinate system was used in an adaptive filtering procedure to improve the state of the satellite in one pass.

Arur, M. G.↗
NASA NTRS1980

Improved position and new optical candidate for A0538-66

An analysis of HEAO 1 modulation collimator data leading to an improved position determination and a new optical counterpart candidate for the transient X-ray source A0538-66 is reported. Data obtained during five outbursts, all of which were separated by 16.7 days or a small multiple thereof, indicates that the outbursts, although of varying duration, intensity, and hardness ratio originated from the same source, at a position of 5 h 35 min 42.7 sec RA and 66 deg 53 arcmin 44 arcsec dec. The improved position determination is found to exclude the previously suggested optical counterpart, and a search of archive plates of the Large Magellanic cloud in the refined error regions has lead to the tentative identification of a B-type star with an observed B variability of 1 mag with the X-ray source.

Johnston, M. D.↗
NASA NTRS1981

A magnetospheric signature of some F layer positive storms

Calculations of electron density distributions in the global thermosphere-ionosphere system perturbed by high-latitude thermospheric heating are presented which indicate a link between the heating and magnetospheric plasma disturbances near the equator. The calculations were made using a self-consistent model of the global sunlit thermosphere-ionosphere system describing the evolution of equatorial plasma disturbances. The heat input is found to cause electron density enhancements that propagate along magnetic field lines from the F2 maximum over mid-latitudes to the equator in the magnetosphere and which correspond to the positive phase of an F layer storm. The positive phase is shown to be generated by the induction of equatorward winds that raise the mid-latitude F layer through momentum transfer from neutral atoms to ionospheric ions, which ions pull electrons with them. Model results are used to identify plasma signatures of equatorward winds and an intensified magnetospheric electric field in Explorer 45 and Arial 4 measurements taken during the positive phase of an F layer storm.

Miller, N. J.↗
NASA NTRS1981

Positive cloud-to-ground lightning flashes in severe storms

The occurrence of cloud-to-ground flashes that effectively lower positive charge to earth (+CG flash) over flat terrain has been documented in the mature stage of severe thunderstorms. Of the 31 documented +CG flashes, most had only one return stroke. Zero-to-peak rise times for the strokes averaged 7 microsec. The +CG flashes averaged 520 ms in duration, with 25 percent lasting more than 800 ms. Many of these had field changes suggestive of continuing current. Positive flashes have been observed to emanate from several regions of severe storms: high on the back of the main storm tower, through the wall cloud, and from the downshear anvil. Visually most of these positive flashes have emanated from high in the storm, and acoustic mapping of two shows thunder sources to a height of about 15 km.

Rust, W. D.↗
NASA NTRS1981

Position surveillance using one active ranging satellite and time-of-arrival of a signal from an independent satellite

A satellite-aided mobile communication service was tested for position surveillance, with an automatic responder circuit connected between the vehicle receiver and transmitter, and a receiver coded for signals from another satellite. Using the ATS-6 and GOES satellites, a tone-code ranging transponder was connected between the receiver and transmitter, and a 468 MHz receiver was connected to the responder unit for passive reception of the 100 bit per second timing and data signal. Results showed lines of position derived from the active ranging through ATS-6 to be accurate to approximately 0.1 nautical mile, while the NOAA-GOES signals were accurate to about 1.6 miles. The active ranging bandwidth was 2.44 kHz, and the integration time was 0.1 second, while the limitation on accuracy was the 100 Hz bandwidth. This technique of position surveillance was concluded to be feasible and simple to operate, providing needed, good quality communications to the inland waterways industry.

Anderson, R. E.↗
NASA NTRS1981

Design studies for a technology assessment receiver for global positioning system

The operational conditions of a radio receiver - microprocessor for the global positioning system are studied. Navigation fundamentals and orbit characterization are reviewed. The global positioning system is described with emphasis upon signal structure and satellite positioning. Ranging and receiver processing techniques are discussed.

Painter, J. H.↗
NASA NTRS1982

Navstar/Global Positioning System

The Global Positioning System (GPS) was developed to provide highly precise position, velocity, and time information to users anywhere in the area of the Earth and at any time. The GPS, when fully operational, will consist of 18 satellites in six orbital planes. Any GPS user, by receiving and processing the radio signals from the satellite network can instantaneously determine navigation information to an accuracy of about 15 m in position and 0.1 m/s in velocity. The GPS is compared with other systems such as Loran-C, Omega, TACAN and Transit.

Ananda, M.↗
NASA NTRS1981

Positive ion observations in the middle magnetosphere of Jupiter

The positive ion data gathered by the Voyager Plasma Science experiment in the middle magnetosphere of Jupiter are considered. It is pointed out that the experiment measures positive ions with energies per charge between 10 and 5950 V. The observations are analyzed to derive the mass and charge densities, velocity components, and temperatures of the low-energy plasma population. The reduced data set is discussed in terms of the outstanding questions concerning this plasma population and its dynamics. It is found that on the dayside there exists a transonic to highly supersonic positive ion population which tends to move azimuthally but does not rigidly corotate with the planet.

Mcnutt, R. L., Jr.↗