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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 1,369 records · Page 76
All sourcesNASA NTRSDOE OSTI
NASA NTRS1983

Identification of forbidden transitions in the nu-4 band of (N-14)H3 by intracavity laser-Stark spectroscopy

These transitions are forbidden in the sense that they follow the selection rule delta K = + or - 2, which violates the usual rule that delta K = + or - 1 for a perpendicular band of a symmetric top, where K is the projection of the total angular momentum onto the molecular symmetry axis. The assignments are based for the most part on laser-Stark measurements made with a CO laser and an intracavity Stark cell. The procedure followed in making the assignments is described. Attention is called to the significance of these new lines in the analysis of the nu-4 vibrational state and in an improved determination of the ground-state rotational and centrifugal distortion constants.

Weber, W. H.↗
NASA NTRS1983

Proceedings of a Workshop on Assessment of Techniques for Measuring Tropospheric N sub x O sub y

Human impact on the troposphere, particularly on the regional to global scale is assessed. One area of required research is instrumentation development, which is aimed at improving the capability to measure important trace gases and aerosols which are key species in the major atmospheric biogeochemical cycles. To focus on specific needs, the Instrumentation Workshop for NxOy Tropospheric Species was conducted. The workshop discussed measurement needs and instrument capabilities for NxOy species, including NO, NO2, HNO3, HNO2, PAN, and NO3 aerosols. The status and measurement capabilities of various techniques (operational as well as conceptual) were discussed, along with future instrument and technology needs.

Source record↗
NASA NTRS1984

Thermoset-thermoplastic aromatic polyamide containing N-propargyl groups

The compounds of the class of aromatic polyamides useful as matrix resins in the manufacture of composites or laminate fabrication were developed. The process for preparing this thermoplastic-thermoset polyamide system involves incorporating a latent crosslinking moiety along the backbone of the polyamide to improve the temperature range of fabrication thereof wherein the resin softens at a relatively low temperature (approx. 154 C) and subsequently sets-up or undergoes crosslinking when subjected to higher temperature (approx. 280 C).

St.clair, T. L.↗
NASA NTRS1984

Interaction of the ABL with stratocumulus and cumulus cloud layers, appendix N

The role of the atmospheric boundary layer (ABL) over the oceans which in the general circulation of the atmosphere is to supply moisture to cumulus and stratus clouds is outlined. In extreme weather events, such as powerful storms and intense droughts, the primary role of the ABL is to supply or deny moisture to the weather system. Even for routine weather regimes, cloudiness and precipitation are key elements of any forecast. The premier problem for ABL parameterization is to formulate the physical coupling between the ABL turbulence and the clouds.

Randall, D. A.↗
NASA NTRS1984

Stratospheric NO and NO2 profiles at sunset from analysis of high-resolution balloon-borne infrared solar absorption spectra obtained at 33 deg N and calculations with a time-dependent photochemical model

Simultaneous stratospheric vertical profiles of NO and NO2 at sunset were derived from an analysis of infrared solar absorption spectra recorded from a float altitude of 33 km with an interferometer system during a balloon flight. A nonlinear least squares procedure was used to analyze the spectral data in regions of absorption by NO and NO2 lines. Normalized factors, determined from calculations of time dependent altitude profiles with a detailed photochemical model, were included in the onion peeling analysis to correct for the rapid diurnal changes in NO and NO2 concentrations with time near sunset. The CO2 profile was also derived from the analysis and is reported.

Rinsland, C. P.↗
NASA NTRS1984

Determination of the stiffness reduction of (0,90, + or - N 45) graphite/epoxy laminates under cyclic loading

A series of tests has been performed to determine the effect of fatigue loading on the stiffness degradation of graphite/epoxy composite materials. Specimens were tested in tension-tension fatigue at a loading frequency of 10 Hz and a stress ratio of 0.1, for a wide range of stress levels. During this investigation, both static and dynamic stiffnesses were continually monitored for the range of stress levels tested, and the results are presented in tabular and graphical form.

Jones, D. L.↗
NASA NTRS1984

Remote sensing of weather and climate parameters from HIRS2/MSU on Tiros-N

At the Goddard Laboratory for Atmospheric Sciences (GLAS) a physically based satellite temperature sounding retrieval system, involving the simultaneous analysis of HIRS2 and MSU sounding data, has been developed for determining atmospheric and surface conditions which are consistent with the observed radiances. In addition to determining accurate atmospheric temperature profiles even in the presence of cloud contamination, the system provides global estimates of day and night sea or land surface temperatures, snow and ice cover, and parameters related to cloud cover. The inverse radiative transfer equation approach to the multi-spectral analysis of the data, and details of its implementation, are described. Ice, snow, and cloud fields derived for January 1979 are consistent with other measures of similar parameters obtained from AVHRR and SMMR. Monthly mean sea-surface temperature fields agree with those derived from ship and buoy measurements to 0.5 C.

Susskind, J.↗
NASA NTRS1984

RS CV sub n binary systems

An attempt is made to place in context the vast amount of data obtained as a result of X-ray, ultraviolet, optical, and microwave observations of RS CVn and similar spectroscopic binary systems. Emphasis is on the RS CVn systems and their long period analogs. The following questions are considered: (1) are the original defining characteristics still valid and still adequate? (2) what is the evidence for discrete active regions? (3) have any meaningful physical properties for the atmospheres of RS CVn systems been derived? (4) what do the flare observations tell about magnetic fields in RS CVn systems? (5) is there evidence for systematic trends in RS CVn systems with spectral type?

Linsky, J. L.↗
NASA NTRS1984

Weather and Climate Parameters from Tiros-n

The objective of the research is to develop a processing system for analysis of HIRS2/MSU data on the TIROS/NOAA meteorological satellites to be used both to improve forecasting skill and to develop climatological data for at least a five year period. Research involves both the development of improved techniques and validation studies of the retrieved products.

Sussking, J.↗
NASA NTRS1985

Ignition of mixtures of SiH sub 4, CH sub 4, O sub 2, and Ar or N sub 2 behind reflected shock waves

Ignition delay times in mixtures of methane, silane, and oxygen diluted with argon and nitrogen were measured behind reflected shock waves generated in the chemical kinetic shock tube at Langley Research Center. The delay times were inferred from the rapid increase in pressure that occurs at ignition, and the ignition of methane was verified from the emission of infrared radiation from carbon dioxide. Pressures of 1.25 atm and temperatures from 1100 K to 1300 K were generated behind the reflected shocks; these levels are representative of those occurring within a supersonic Ramjet combustor. Expressions for the ignition delay time as a function of temperature were obtained from least squares curve fits to the data for overall equivalence ratios of 0.7 and 1.0. The ignition delay times with argon as the diluent were longer than those with nitrogen as the diluent. The infrared wavelength observations at 4.38 microns for carbon dioxide indicated that silane and methane ignited simultaneously (i.e., within the time resolution of the measurement). A combined chemical kinetic mechanism for mixtures of silane, methane, oxygen, and argon or nitrogen was assembled from one mechanism that accurately predicted the ignition of methane and a second mechanism that accurately predicted silane hydrogen ignition. Comparisons between this combined mechanism and experiment indicated that additional reactions, possibly between silyl and methyl fragments, are needed to develop a good silane methane mechanism.

Mclain, A. G.↗
NASA NTRS1985

Some negative results in N-sided patches

To ease surface definition in situations of complex topology, patches with other than four sides and with guaranted continuity of at least slope with adjacent patches are needed. There are known techniques in the literature for three- and five-sided patches of reasonably economy, and known transfinite methods for many sides. Some of the conditions that a six-sided patch must satisfy and how certain simpler approaches are not effective are shown.

Sabin, M.↗
NASA NTRS1985

The mean ionic charges of N, Ne, MG, SI and S in solar energetic particle events

The mean ionic charges of nitrogen, neon, magnesium, silicon, and sulfur in solar flare particle events were determined for 12 flares during the time interval from September 1978 to September 1979. The observations were carried out with the MPI/UoMd ULEZEQ Sensor on the ISEE-3 satellite comparing the results with mean charge states established in a hot coronal plasma under equilibrium conditions, different temperatures for different elements are discussed. These range from approx. 2 million K to 7 million K in a single flare. From flare to flare the variation in temperature for each element is less than the variation between different ion species.

Luhn, A.↗
NASA NTRS1984

Observable in the reversible reaction gamma + d yields n + p

Calculations are presented on the effect of the two-body charge and current density effects on the observables in the photodisintegration of a deuteron. The computations are performed in a cartesian coordinate system, initially for gamma rays plane-polarized in the x-direction. Unpolarized photons are treated with an incoherent superposition of transition amplitudes for gamma rays polarized in the x- and y- directions. Account is taken of recoil and interaction energies after an initial state is defined. Consideration is focused on the cross section, polarization, and asymmetry of the reaction at low and medium energy incident gamma rays.

Rustgi, M. L.↗
NASA NTRS1985

Population mechanisms for the He(+) n = 3 levels determined from measurements of the solar 1640 A emission

The 1640 A line profile is analyzed using solar data obtained by the NRL slit spectrograph on Skylab. Data from coronal hole regions, quiet sun regions, active regions, prominence regions, and flare regions are presented. The relative densities of 3s, 3p, and 3d levels are determined from the data, and the dominant population mechanisms for these levels are inferred using a rate equation model for the He(+) ion. The relative importance of collisional excitation, radiative recombination, and photoexcitation is determined for each of the solar regions.

Seely, J. F.↗