Search NASA⌕ Search

SEARCH · Search NASA

Results for “formatting”

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 901 records · Page 50
All sourcesNASA NTRSDOE OSTI
NASA NTRS1983

The morphology and kinematics of the Cep IV star formation region

Rossano et al. (1980) have discussed the morphology and kinematics of Cep IV star formation region. The present investigation is concerned with H2CO observations which have been conducted to examine the relationship between the neutral and ionized gas in the Cep IV star formation region and to study the origin of the unusual kinematics and morphology of the stars, gas, and dust in this region. Six-cm H2CO observations were undertaken throughout a one half degree square area centered on the H II region W1. In addition, VLA observations of the Cep IV region at 6 and 20 cm were also performed. The neutral gas in the vicinity of W1 is found to be located in clouds having velocities of -13, -7, and 1 km/s. The gas at - 7 km/s appears to be undisturbed gas from the original dark cloud complex.

Grayzeck, E. J.↗
NASA NTRS1984

Deposit formation and heat transfer in hydrocarbon rocket fuels

An experimental research program was undertaken to investigate the thermal stability and heat transfer characteristics of several hydrocarbon fuels under conditions that simulate high-pressure, rocket engine cooling systems. The rates of carbon deposition in heated copper and nickel-plated copper tubes were determined for RP-1, propane, and natural gas using a continuous flow test apparatus which permitted independent variation and evaluation of the effect on deposit formation of wall temperature, fuel pressure, and fuel velocity. In addition, the effects of fuel additives and contaminants, cryogenic fuel temperatures, and extended duration testing with intermittent operation were examined. Corrosion of the copper tube surface was detected for all fuels tested; however, plating the insides of the tubes with nickel reduced deposit formation and eliminated corrosion in most cases. The lowest rates of carbon deposition were obtained for natural gas, and the highest rates were obtained for propane. Forced-convection heat transfer film coefficients were satisfactorily correlated using a Nusselt-Reynolds-Prandtl number equation for all the fuels tested.

Giovanetti, A. J.↗
NASA NTRS1984

Formation and inflammation of a turbulent jet

The formation and inflammation of a planar, turbulent jet in an incompressible medium is modeled numerically by the use of the random vortex method amended by a flame propagation algorithm. The results demonstrate the dominant influence of turbulent eddies and their interactions upon the development of the jet. Its growth is shown to consist of three stages: formation of small eddies, pairing of eddies with the same sign of circulation, and pairing of eddies of opposite signs. On this basis a number of features of the jet mechanism are revealed, namely penetration, engulfment, entrainment, and intermittency. Two cases of inflammation are considered. In one, the jet is ignited at the center of the orifice, the solution tracing its own inflammation. In the other, combustion is initiated across its full cross section, the results modeling the action of a turbulent torch as it spreads the flame into the combustible surroundings. In both cases the flow field is still dominated by the turbulent eddies and their interactions. However, the coherence among them is encumbered as a consequence of expansion due to the exothermicity of the combustion process.

Ghoniem, A. F.↗
NASA NTRS1983

Observations on the connectivity of the parvicellular reticular formation with respect to a vomiting center

The intrinsic and extrinsic connections of the parvicellular reticular formation (PCRF) that have been demonstrated by fiber degeneration studies and studied by more recently introduced horseradish peroxidase retrograde cell labeling are reviewed in an attempt to delimit the connectivity of the region in the PCRF where electrical stimulation produced emesis. Evidence is presented that certain specific functional subdivisions in PCRF such as the salivatory nuclei and the cells which give rise to the vestibular efferent projections can be delimited. An attempt is made to differentiate the sources of brain stem afferent connections with the nucleus of the tractus solitarius, the vagal nucleus and the nucleus ambiguus complex. The literature bearing on the histochemistry of the brain stem is reviewed in a search for clues to possible unique histo- or immunochemical cytological subdivisions in the parvicellular reticular formation.

Mehler, W. R.↗
NASA NTRS1984

Chromium silicide formation by ion mixing

The formation of CrSi2 by ion mixing was studied as a function of temperature, silicide thickness and irradiated interface. Samples were prepared by annealing evaporated couples of Cr on Si and Si on Cr at 450 C for short times to form Si/CrSi2/Cr sandwiches. Xenon beams with energies up to 300 keV and fluences up to 8 x 10 to the 15th per sq cm were used for mixing at temperatures between 20 and 300 C. Penetrating only the Cr/CrSi2 interface at temperatures above 150 C induces further growth of the silicide as a uniform stoichiometric layer. The growth rate does not depend on the thickness of the initially formed silicide at least up to a thickness of 150 nm. The amount of growth depends linearly on the density of energy deposited at the interface. The growth is temperature dependent with an apparent activation energy of 0.2 eV. Irradiating only through the Si/CrSi2 interface does not induce silicide growth. It is concluded that the formation of CrSi2 by ion beam mixing is an interface-limited process and that the limiting reaction occurs at the Cr/CrSi2 interface.

Shreter, U.↗
NASA NTRS1984

Dynamics of dendritic pattern formation

This paper is a brief review of recent and ongoing developments in the theory of dendritic pattern formation. A marginal stability hypothesis has achieved some success in predicting dendritic growth rates, but a fully nonlinear dynamic theory of the dendritic growth mechanism has yet to be developed. A possible clue for the construction of such a theory is the existence of a class of one-dimensional models in which a pattern is found to spread into an unstable region by propagating at the slowest stable speed. This mathematical realization of the marginal stability mechanism has led to the development of a boundary layer model which describes localized dynamics of fully two- or three-dimensional solidification fronts and which retains some of the mathematical features of the propagating systems. Preliminary results of numerical calculations using the boundary layer model indicate that it is capable of probing fully nonlinear features of dendritic pattern formation.

Langer, J. S.↗
NASA NTRS1984

Venus banded terrain - Tectonic models for band formation and their relationship to lithospheric thermal structure

Two classes of tectonic models for the formation of band structure on Venus mountain ranges are quantitatively evaluated: folding models and extensional models. The characteristics of banded terrain on Ishtar Terra are reviewed, particularly the evidence for a tectonic origin and such important details of band geometry as the spacing between adjacent bands. The tectonic models are tested against these observed features, and it it shown that both classes of models are possible explanations of banded terrain as long as the outer elastic-brittle layer of the Venus crust is at most a few kilometers thick. A general assessment is given of hypotheses for the origin of banded terrain and of the relationship between mechanical models for band formation and the thermal structure of the Venus lithosphere.

Solomon, S. C.↗
NASA NTRS1984

The millimeter and submillimeter laboratory spectrum of methyl formate in its ground symmetric torsional state

Over 200 rotational lines of methyl formate in its ground (v sub t = 0), symmetric (A) torsional state have been measured in the frequency range 140-550 GHz. Analysis of these and lower frequency transitions permits accurate prediction (below 0.1 MHz) of over 10,000 transitions at frequencies below 600 GHz with angular momentum J lower than 50. The measured spectral lines have permitted identification of over 100 new methyl formate lines in Orion.

Plummer, G. M.↗
NASA NTRS1984

Report format preferences of technical managers and nonmanagers

A survey of engineers and scientists concerning the format of NASA technical reports indicates that a summary as well as an abstract should be included, that the definitions of symbols and glossary of terms should be located in the front of the report, and that the illustrative material should be integrated with the text rather than grouped at the end of the report. Citation of references by number, one-column, ragged-right-margin layout, and third-person writing style are also preferred by a majority of the respondents. The preferences of managers and nonmanagers are very similar for all aspects of technical report format covered by the survey.

Pinelli, T. E.↗
NASA NTRS1983

Standard format data units - Tools for automatic exchange of space mission data

A set of standard formatting rules for the data sets, and a standard computer-readable language with which to describe the data, are two tools which are used to create the Standard Format Data Unit (SFDU). The NASA/JPL proposal for creation and utilization of SFDUs is presented, and its relationship to recommendations from the Consultative Committee for Space Data Systems (CCSDS) is discussed. Several current and planned implementations of the SFDU concept among major space flight projects are identified. The purpose of creating the concept of an SFDU is to allow members of the science community to share national and global resource data independently of project or program. The feedback from SFDU implementation efforts is considered an essential part of the CCSDS activity. Even though the CCSDS specifically deals with space data systems, the SFDU concept can be applied to practically every data system on an open network. The SFDU is in the early phase of CCSDS standard definition work, and must go through several other phases before being formally recommended as an international standard.

Willett, J. B.↗
NASA NTRS1984

The influence of gravitational body force in meteoritic chondrule and lunar glass formation

The effects of gravitational body force must be considered in the formation of extraterrestrial materials such as meteoritic chondrules and lunar glasses. Solidification experiments conducted in microgravity as well as g values greater than Earth's gravitational force have demonstrated that gravitational force can have profound and sometimes unexpected effects upon the way materials solidify and, therefore, upon their physical and mechanical properties. Solutal, thermal and sedimentation effects differ from those experienced on Earth. Because buoyancy forces are reduced, materials of different densities may remain in close proximity. The spherical morphology of chondrules and many lunar glasses may reflect the tendency for free floating liquids to form spherical droplets in a microgravity environment, a form which minimizes surface energy. Under these conditions, surface energy forces dominate gravity forces. The formation of two common chondrule textures, barred and radiating chondrules, can be explained using observations from glass science.

Budka, P. Z.↗
NASA NTRS1984

Star Formation in Globules

The low mass star formation process was studied by application of submillimeter and supplementing far-infrared continuum observations by molecular line observations to the discovery and analysis of compact cores in molecular clouds with low luminosity. These dense regions are likely to be the sites where a cloud has recently collapsed or is still collapsing to form a star. Observations show that nonisotropic effects must play an important role in star formation. Four low luminosity sources embedded in the clouds L1551, B335, L1455 and L723 are presented. All these sources exhibit collimated bipolar molecular outflows of varying strengths. Data on the outflows are combined with determinations of mass, luminosity and temperature of the dust in the dense cores surrounding these embedded energy sources, to infer the evolutionary stage of the object. The possible role of the cores in channeling or generating the outflow is examined.

Davidson, J. A.↗
NASA NTRS1985

The Deep Structure of Lunar Basins: Clues to the Understanding of Basin Formation and Modification

Basin excavation has played a major role in shaping the surface and subsurface of the Moon. Though photogeologic observations provide estimates for the present volumes of lunar impact basins and their ejecta deposits, there is not sufficient information to describe completely either the geometry of the basins at the time of impact or their modification with time. Determination of the structure of the crust and upper mantle beneath large basins can provide important insight into the thermal and mechanical processes associated with basin formation and modification as well as the differences in these processes as functions of basin age and size. Using observed gravity and topography together with the seismically determined crustal thickness of the central nearside, a model for the structure of the crust and upper mantle of the nearside of the Moon is presented. With this model the deep structure of the largest lunar basins are compared. The implications for the processes of basin formation and modification at different stages in lunar history are explored.

Bratt, S. R.↗
NASA NTRS1984

Deep Water Formation

Some simple arguments on plumes of dense water and filling boxes were given. What determines the time for a large-scale environment to be modified by the injection of dense water at its edge is the mass flux, not the buoyancy flux. However, it is the denser buoyancy flux, when there are several competing plumes (e.g., the Mediterranean outflow versus the Denmark Strait outflow) that determines which plume will provide the bottom water for that ocean basin. It was noted that the obvious laboratory experiment (rotate a pie-shaped annulus, and heat/cool it on the surface) had never been performed. Thus, to some extent our belief that deep convection is somehow automatic at high latitudes to close off some ill-defined meridional circulation has never been tested. A summary of deep convection was given. The two fundamental formation mechanisms were shown. Of the two, it is open-ocean convection which forms the water which supplies the Denmark Strait overflow -- in all likelihood, as formation in the Greenland Sea remains stubbornly unobserved. But it is the slope convection which finally creates North Atlantic deep water, following the Denmark Strait overspill.

Killworth, P. D.↗
NASA NTRS1984

Quaternary North Atlantic Surface Paleoceanography in Regions of Potential Deep-water Formation

At the time scale of the Quaternary climate cycles, the sites of formation of North Atlantic Deep Water are not known. The interglacial extreme is presumably exemplified by the modern regions; the Norwegian, Greenland and Labrador Seas. During the major glacial-age coolings in the North Atlantic, the sites may have shifted well to the south, perhaps as far as the limit of the polar front at 40 to 50 N. Still other sites may have been important during intermediate climatic conditions. Because of the close coupling of high-latitude surface waters to North Atlantic Deep Water in the modern ocean, the history of sea-surface temperature (SST) oscillations across the high-latitude North Atlantic is relevant to an understanding of deep-water formation on the longer time scales.

Ruddiman, W. F.↗
NASA NTRS1985

Contribution functions for Zeeman-split lines, and line formation in photospheric faculae

The transfer of polarized light in an inhomogeneous stellar atmosphere, and the formation of magnetically sensitive spectral lines, are discussed. A new method for the solution of the transfer equations is proposed. The method gives a natural definition of the contribution functions for Stokes' parameters, i.e., functions describing the contributions from different parts along the line-of-sight (LOS). The formalism includes all magneto-optical effects, and allows for an arbitrary variation of magnetic field, velocity field, temperature, density, etc., along the LOS. The formation of FeI lambda 5250.2 in photospheric faculae is described. A potential-field model of a facular element is presented, and spectra profiles and contribution functions are computed for the Stokes parameters I, Q, and V.

Vanballegooijen, A. A.↗
NASA NTRS1985

Large format camera photographs: A new tool for understanding arid environments

Large Format Camera (LFC) was developed by NASA to produce high resolution stereo photographs from space with maximum photogrammetric fidelity. The camera has a 30.5 cm focal length lens and an f/6.0 aperture. The optics are corrected to permit operation with black and white (b/w), natural color (col) and color infrared (cir) film. Interchangeable minus-haze and minus-blue filters are located near the aperture stop, and an antivignetting filter is provided on the front element of the lens. The field-of-view of the LFC along track is 73.7 degrees (ratio 1.5 x H) and across track is 41.1 degrees (ratio 0.75 x H). The frame format of the LFC is 23x46 cm with the long dimension in the direction of flight. The camera can be operated to produce 10, 60, 70, or 80 percent forward overlap for stereoscopic coverage. With 80 percent forward overlap, the stereo model base height ratio is 0.3 for successive frames and 1.2 if every fourth frame is used. The LFC magazine has a capacity of 2400 frames. Two horizon-looking stellar cameras, one directed 45 degrees forward and the other 45 degrees aft were used to photograph the star field in synchronism with exposures of the LFC. Post flight mensuration and calculation of the stellar photographs will provide altitude information for the LFC.

Walker, A. S.↗
NASA NTRS1985

Conditions during formation of the Earth

The formation of the Earth starts with gravitational instabilities in the gas of primitive solar nebula, which form giant gaseous protoplanets. The envelopes of these are thermally evaporated, but solids can gravitationally settle to the center of the protoplanets, and most of the core and mantle of the Earth were formed at that time (age about 10,000 years). The protoearth then survived a period of high temperatures in the surrounding gas (age about 10 to the 5th years). While and after the gas was thermally stabilized and removed from the solar system, the Earth grew by bombardment of planetesimals and its early atmosphere was established. A late major collision led to formation of the Moon and loss of the primordial atmosphere (age about 10 to the 8th years). The present atmosphere resulted from still later accretion. The presence of this atmosphere spreads out the mantle cooling and solidification over hundreds of millions of years.

Cameron, A. G. W.↗