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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 865 records · Page 48
All sourcesNASA NTRSDOE OSTI
NASA NTRS1985

The calculation of theoretical chromospheric models and the interpretation of solar spectra from rockets and spacecraft

Solar chromospheric models are described. The models included are based on the observed spectrum, and on the assumption of hydrostatic equilibrium. The calculations depend on realistic solutions of the radiative transfer and statistical equilibrium equations for optically thick lines and continua, and on including the effects of large numbers of lines throughout the spectrum. Although spectroheliograms show that the structure of the chromosphere is highly complex, one-dimensional models of particular features are reasonably successful in matching observed spectra. Such models were applied to the interpretation of chromospheric observations.

Avrett, E. H.↗
NASA NTRS1985

Theoretical interpretation of thermal arrest data from differential thermal analysis measurements

A theory was developed to interpret the thermal arrest data of HgCdTe system from differential thermal analysis measurements. A nonlinear regression program is used to model fit the data. The purpose is to obtain a set of parameters which will give the information about average radiation coefficient, latent heat of fussion, and specific heat of the HgCdTe system at various compositions. The liquidus and solidus at various compositions are also obtained. The heat radiation from the furnace, heat radiation from the system, heat capacity from both the system and the quartz tube and the heat of fusion of the system are considered, however, it neglects heat transfer through conduction and convection.

Wang, J. C.↗
NASA NTRS1985

Characterization of LANDSAT-4 TM and MSS Image Quality for the Interpretation of California's Agricultural Resources

The quality of LANDSAT-4 MSS and TM data was determined by analyzing TM spectral and spatial performance in terms of spectral variability of natural targets and the TM-ground instantaneous field-of-view (IFOV) variability in level and mountainous terrain; and by assessing the suitability of TM and MSS image products for characterizing renewable resourse features. The TM data should be extremelly valuable for crop type and area proportion estimation; undating agricultural land use survey maps at 1:24,000 scale and smaller, field boundary definition; and determining the size and location of individual farmsteads. Ongoing research activities are focused on making spectral and spatial analyses of both MSS and TM analytical film products. The improved spectral, spatial, and radiometric quality of the TM data, should promote a renewed emphasis and interest in direct visual interpretation of these image products, both for updating and improving land stratification in support of resource inventory and for enhancing the image analyst's contribution to computer-assisted analysis procedures.

Degloria, S. D.↗
NASA NTRS1983

Data selection techniques in the interpretation of MAGSAT data over Australia

The MAGSAT data require critical selection in order to produce a self-consistent data set suitable for map construction and subsequent interpretation. Interactive data selection techniques are described which involve the use of a special-purpose profile-oriented data base and a colour graphics display. The careful application of these data selection techniques permits validation every data value and ensures that the best possible self-consistent data set is being used to construct the maps of the magnetic field measured at satellite altitudes over Australia.

Johnson, B. D.↗
NASA NTRS1985

Improving the geological interpretation of magnetic and gravity satellite anomalies

Current limitations in the quantitative interpretation of satellite-elevation geopotential field data and magnetic anomaly data were investigated along with techniques to overcome them. A major result was the preparation of an improved scalar magnetic anomaly map of South America and adjacent marine areas directly from the original MAGSAT data. In addition, comparisons of South American and Euro-African data show a strong correlation of anomalies along the Atlantic rifted margins of the continents.

Hinze, W. J.↗
NASA NTRS1984

Some recent developments in the interpretation of MST radar returns from clear air (keynote paper), part 2

Mesosphere-stratosphere-troposphere (MST) radar returns from clear air come about through the interaction of electromagnetic waves with the inhomogeneous structures of refractive index in the atmosphere. In order to interpret the data correctly to obtain information concerning the dynamics of the atmosphere, one must first know how the various refractive index structures can affect the propagation and scattering of the radio waves. This can be achieved through theoretical and model studies. On the other hand, in order to carry out realistic theoretical studies, realistic models of the inhomogeneous structures of the atmospheric refractive index are needed. These are available only through observational data. Therefore the close interplays between theoretical and observational investigations are essential in making progress in this area. Some results on certain aspects of the problem are presented with emphasis on those aspects that may lead to new developments.

Liu, C. H.↗
NASA NTRS1985

The interpretation of flying qualities requirements for flight control system design

An experimental flight test program was designed for the Total In Flight Simulator (TIFS) directed toward the interface between flying qualities requirements and flight control system design criteria. The eventual goal is to provide an interpretation or translation of flying qualities requirements for use by the flight control system designer. Specifically, an angle of attack and pitch rate command system matrix involving both short term and long term dynamics are specified for evaluation. Flying qualities criteria and flight control system configuration or architecture can be independent was demonstrated. Finally, additional configurations are proposed to evaluate the efficacy of dynamic decoupling.

Rynaski, E. G.↗
NASA NTRS1984

A geological interpretation of Seasat-SAR imagery of Jamaica

Spaceborne radar imagery obtained from Seasat allows an unobscured large-scale view of Jamaica that can be used for geological interpretation. Lineaments and textures visible in these images were mapped and compared with the known geology of the Tertiary karst limestones covering the central and western parts of the island. Some of these radar textures correlate with lithological units, while others follow tectonically-controlled zones or structural blocks. Mapping of radar lineaments has led to the recognition of three new aspects of Jamaican faults: (1) a major through-going NE-SW fault system, termed here the Vere-Annotto lineament; (2) a series of curving scissor faults in the central part of the island; and (3) the related observation that the dominant NNW-SSE tectonic fabric of the central part of the island takes the form of an elongate sigmoid in plan view. During most of the Neogene Jamaica has been part of an active zone of left-lateral transform motion between the Caribbean and North American plates and is a region of anomalous uplift. The radar imagery is a sensitive recorder of the deformation undergone by the karst limestones in this tectonic regime. Some of the observations are explained with models for a complex, evolving shear zone.

Wadge, G.↗
NASA NTRS1984

Interpretation of the lunar microwave brightness temperature spectrum - Feasibility of orbital heat flow mapping

The feasibility of an orbital mapping of heat flow by means of microwave radiometers is examined on the basis of a detailed model of the lunar regolith. The results obtained are discussed in terms of contributions of physical properties and regolith structure to the spectral signature of lunation-averaged brightness temperatures. Even for regions for which remote heat flow detection is not feasible, detailed interpretations of remote measurements in terms of physical properties and regolith structure could be made by means of the model presented. Surface and subsurface scattering effects are considered in evaluating possible wavelength dependencies of the microwave emissivity.

Keihm, S. J.↗
NASA NTRS1983

The spectrum of high energy cosmic-ray electrons - Results and interpretation

Results of a measurement of high energy cosmic-ray electrons that was performed with a balloon-borne transition radiation/shower detector telescope are presented. The data cover the energy range from 5 to 300 GeV. The interstellar spectrum below 10 GeV, which is affected by solar modulation, is derived through analysis of the nonthermal galactic radio emission, and extended to lower energies (about 300 MeV). The interstellar differential spectrum is described by a power law dependence on E with an index of -1.4 below 2 GeV, but attaining a slope of -2.6 at 2-10 GeV, and steepening further to almost -3.6 at 30-300 GeV. The features of this spectrum are interpreted in the context of galactic propagation models, assuming that the spectrum at the acceleration site has the form of a single power law. It is concluded that: (1) regions outside the galactic disk contribute to the confinement volume of electrons, (2) the containment time of electrons is of the order 10 to the 7th years and is independent of energy, (3) the spectrum at the acceleration site has a power law exponent equal to -2.65, and (4) a specific mechanism is responsible for the apparent flattening of the electron spectrum below 2 GeV.

Muller, D.↗
NASA NTRS1984

Recent advances in understanding stratospheric dynamics and transport processes - Application of satellite data to their interpretation

The present paper discusses the use of the transformed Eulerian (or 'residual') mean-flow formulation, the Eliassen-Palm flux, and Ertel's potential vorticity to provide an increased understanding of wave, mean-flow interactions, and constituent transport processes in the stratosphere. Temperature and ozone data retrieved from radiance profiles obtained by the LIMS instrument on the Nimbus 7 satellite are utilized in conjunction with these theoretical concepts for the interpretation of phenomena that occurred during the major and minor warmings of January-February 1979. The results illustrate the insight provided by these concepts and demonstrate that useful diagnostic quantities can be derived from global satellite temperature fields.

Grose, W. L.↗
NASA NTRS1985

Theoretical interpretation of the observed interplanetary magnetic field radial variation in the outer solar system

Observations of the azimuthal component of the IMF are evaluated through the use of an MHD model which shows the effect of magnetic flux tubes opening in the outer solar system. It is demonstrated that the inferred meridional transport of magnetic flux is consistent with predictions by the MHD model. The computed azimuthal and radial magnetic flux deficits are almost identical to the observations. It is suggested that the simplest interpretation of the observations is that meridional flows are created by a direct body force on the plasma. This is consistent with the analytic model of Nerney and Suess (1975), in which such flux deficits in the IMF arise naturally from the meridional gradient in the spiralling field.

Suess, S. T.↗
NASA NTRS1985

The effects of transient rheology on the interpretation of lower mantle viscosity

The role played by transient rheology in the interpretation of mantle viscosity is reexamined. The investigation has been carried out by comparing the amplitude responses with the data of secular variation of J(2), the relative sea-level histories at sites well within the ice margins and at the ice margin like the city of Boston. A linear Burgers body rheology has been assumed in ther lower mantle. The data near the edge of the ice load proves most sensitive to the transient viscosity structure. The non-monotonic behavior of sea-level data near Boston can be explained both by a steady-state lower mantle viscosity of 10 to the 22nd P with a thick lithosphere and by a transient lower mantle rheology but with a thin lithosphere. The long-term viscosity of the lower mantle in this second model has a steady-state value of around 5 x 10 to the 23rd P.

Sabadini, R.↗
NASA NTRS1985

Interpretation of the geoid

The superposition of the first satellite geoid determined by Iszak upon Ootilla's geoid was based on surface gravity determinations. Good agreement was observed except over the Pacific area of the globe. The poor agreement over the Pacific was interpreted as the result of inadequate observations there. Many geoids were determined from satellite observations, including Doppler measurements. It is found that the geoid is the result of density differences in the mantle maintained since the primeval Earth by its finite strength. Various models based on this assumption are developed.

Runcorn, S. K.↗
NASA NTRS1985

Small-scale convection beneath the transverse ranges, California: Implications for interpretation of gravity anomalies

Tomographic inversion of upper mantle P wave velocity heterogeneities beneath southern California shows two prominent features: an east-west trending curtain of high velocity material (up to 3% fast) in the upper 250 km beneath the Transverse Ranges and a region of low velocity material (up to 4% slow) in the 100 km beneath the Salton Trough. These seismic velocity anomalies were interpreted as due to small scale convection in the mantle. Using this hypothesis and assuming that temperature and density anomalies are linearly related to seismic velocity anomalies through standard coefficients of proportionality, leads to inferred variations of approx. + or - 300 C and approx. + or - 0.03 g/cc.

Humphreys, E. D.↗
NASA NTRS1985

Interpretation of F-106B in-flight lightning signatures

Various characteristics of the electromagnetic data obtained on a NASA F-106B aircraft during direct lightning strikes are presented. Time scales of interest range from 10 ns to 400 microsecond. The following topics are discussed: (1) Lightning current, I, measured directly versus I obtained from computer integration of measured I-dot; (2) A method of compensation for the low frequency cutoff of the current transformer used to measure I; (3) Properties of fast pulses observed in the lightning time-derivative waveforms; (4) The characteristic D-dot signature of the F-106B aircraft; (5) An RC-discharge interpretation for some lightning waveforms; (6) A method for inferring the locations of lightning channel attachment points on the aircraft by using B-dot data; (7) Simple, approximate relationships between D-dot and I-dot and between B and I; and (8) Estimates of energy, charge, voltage, and resistance for a particular lightning event.

Trost, T. F.↗
NASA NTRS1986

Analytical ultrasonics for evaluation of composite materials response. Part 1: Physical interpretation

The phenomena associated with the propagation of elastic waves in anisotropic materials are discussed. Wave modes propagating in general directions relative to the material coordinate system are not purely longitudinal nor transverse. Hence the generation of ultrasonic waves by common piezoelectric transducers will generate multiple modes to some extent. The received signals will likely be a combination of different modes. When using two transducers to send and receive ultrasonic waves, deviation of the energy flux vector may reduce the apparent value of the received signal unless the proper orientation of the two transducers with respect to one another is taken into account. And application of reflection from plane boundaries for the purposes of making certain measurements may lead to misinterpretation of results unless one is aware of the differences in multiple mode generation and critical angle phenomena between isotropic and anisotropic materials. When studies or characterizations of composite materials by ultrasonics are to be performed, these phenomena must be taken into consideration so that proper and correct application and interpretation of the measurements can be made. Finally, attention must be drawn again to the fact that composite materials are heterogeneous by definition. The results discussed here have been determined for homogeneous materials only. While the assumption of homogeneity appears to be valid for certain wavelength ranges in composites, future work must continue to study the phenomena of wave propagation in anisotropic, nonhomogeneous materials.

Henneke, E. G., II↗