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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 1,063 records · Page 59
All sourcesNASA NTRSDOE OSTI
NASA NTRS1973

Iron-absorption band analysis for the discrimination of iron-rich zones

The author has identified the following significant results. Study has concentrated on the two primary aspects of the project, structural analysis through evaluation of lineaments and circular features and spectral analyses through digital computer-processing techniques. Several previously unrecognized lineaments are mapped which may be the surface manifestations of major fault or fracture zones. Two of these, the Walker Lane and the Midas Trench lineament system, transect the predominantly NNE-NNW-trending moutain ranges for more than 500 km. Correlation of major lineaments with productive mining districts implies a genetic relationship, the 50 circular or elliptical features delineated suggest a related role for Tertiary volcanism. Color-ratio composites have been used to identify limonitic zones and to discriminate mafic and felsic rock by combing diazo color transparencies of three different ratios. EROS Data Center scene identification number for color composite in this report is ER 1 CC 500. Refinement of enhancement procedures for the ratio images is progressing. Fieldwork in coordination with both spectral and structural analyses is underway.

Rowan, L. C.↗
NASA NTRS1973

Earth physics, overview

Satellite applications in earth and ocean dynamic studies are considered for: earthquake hazard assessment and alleviation; prediction of general ocean circulation, surface currents, and heat transport; monitoring of transient phenomena of the ocean surface, such as sea state and wave conditions, wind-surface interactions and storm searches; and refinement of the global geoid, the gravity and magnetic fields of the earth.

Vonbun, F. O.↗
NASA NTRS1973

Identification, definition and mapping of terrestrial ecosystems in interior Alaska

The author has identified the following significant results. Two new, as yet unfinished vegetation maps are presented. These tend further to substantiate the belief that ERTS-1 imagery is a valuable mapping tool. Newly selected scenes show that vegetation interpretations can be refined through use of non-growing season imagery, particularly through the different spectral characteristics of vegetation lacking foliage and through the effect of vegetation structure on apparent snow cover. Scenes now are available for all test area north of the Alaska Range except Mt. McKinley National Park. No support was obtained for the hypothesis that similar interband ratios, from two areas apparently different spectrally because of different sun angles, would indicate similar surface features. However, attempts to test this hypothesis have so far been casual.

Anderson, J. H.↗
NASA NTRS1973

Prototype partial one-third octave band spectrum analyzer for acoustic, vibration and other wideband data for flight applications

The design refinement of a compact frequency analyzer for measurement and analysis on board flight vehicles is discussed. The analyzer has been constructed in a partial one-third octave band configuration with six filters and detectors spaced by the square root of 10 from 316 Hz to 100,000 Hz and a broadband detector channel. The analyzer has been tested over a temperature range of 40 to 120 F at a pressure of one atmosphere, and at a temperature of 75 F at an absolute pressure of 0.000001 torr, and has demonstrated at least 60 db of dynamic range.

Source record↗
NASA NTRS1972

Basic Transportation Economics

Transportation economics is an integral part of all transportation activities. Refined, detailed, and careful economic analyses consider conduct-performance methodology and the specifications of production, cost and demand functions.

Kneafsey, J. T.↗
NASA NTRS1972

Secondary jet interaction with emphasis on outflow and jet location.

Data were obtained concerning a model which utilized a two-dimensional sonic jet. It was found that outflow and jet location significantly influence the magnitude and behavior of the secondary jet interaction forces. Continued refinements in jet interaction analyses which do not account for outflow are of limited usefulness in the design of control systems for supersonic and hypersonic vehicles. The jet total back pressure ratio increases with either jet pressure ratio or freestream Mach number.

Hefner, J. N.↗
NASA NTRS1973

Gravity field of Mars from Mariner 9 tracking data.

Further reduction of Doppler tracking data from Mariner 9 confirms our earlier conclusion that the gravity field of Mars is considerably rougher than the fields of either the earth or the moon. The largest positive gravity anomaly uncovered is in the Tharsis region which is also topographically high and geologically unusual. The value obtained for the inverse mass of Mars is in good agreement with prior determinations from Mariner fly by trajectories. The direction found for the rotational pole of Mars is in excellent agreement with Sinclair's recent value, determined from earth-based observations of Mars' satellites. Other important physical constants that have either been refined or confirmed by the Mariner 9 data include: (1) the dynamical flattening, (2) the maximum principal moment of inertia, and (3) the period of precession of Mars' pole.

Lorell, J.↗
NASA NTRS1971

The application of a curved, mixed-type shell element.

The variational condition given by Herrmann (1967) for finite element bending analyses of plates is extended to general thin shell problems. Emphasis is laid upon shell behavior and, in particular, on boundary layers and inextensional bending. A study of the boundary layer problem on a cylindrical shell compares the refined element and the Herrmann-Campbell (1968) element. Some numerical results on cross-tube and mitred-bend problems are given.

Visser, W.↗
NASA NTRS1973

An efficient algorithm for calculation of the Luenberger canonical form.

A new algorithm is presented to obtain the Luenberger canonical form for multivariable systems. A distinct feature of the method is that the canonical form is obtained directly and, if necessary, the similarity transformation can be computed. There is a substantial reduction in the amount of computation compared to Luenberger's method. The reduced computations along with Gaussian techniques lend greater inherent accuracy and the ability to refine the solution with additional computations. An example is presented to illustrate the technique.

Jordan, D.↗
NASA NTRS1973

Quasi-monochromatic measurements of homogeneous arc plasmas.

The refined diagnostic information obtainable by high-order spectrometry is illustrated by the results of quantitative measurements of a few rotational lines of OH in the ultraviolet spectrum of water-vapor plasmas generated in a wall-stabilized arc. Because of the high spectral and spatial resolution achieved in end-on measurements, the emission and also the absorption coefficients pertaining to homogeneous arc regions were obtained directly from measured line spectra - although the absorption was not measured explicitly - leading to the occupation of the upper and the lower state for the transition. The gas temperature was determined from the halfwidth of the Doppler-broadened rotational lines. The measured resolving power of the spectrometer was of the order of 400,000 in these measurements.

Klein, L.↗
NASA NTRS1973

The solar radiation pressure on the Mariner 9 Mars orbiter.

The refined mathematical model of the force created by the light pressure of the sun has been used to compute the solar radiation pressure force acting on the Mariner 9 (Mariner Mars 1971) spacecraft, taking into account the reflectivity characteristics of all its components. The results have been compared with values obtained from Mariner 9 observations during the cruise phase and are found to be in agreement within 0.1% of the values.

Georgevic, R. M.↗
NASA NTRS1973

Low-cost fabrication and installation of ablative heat shields for the space shuttle orbiter.

Description of the formulation and evaluation of low-density elastomeric ablative compounds and low-cost techniques for fabricating and installing ablative panels being considered for the Space Shuttle orbiter's thermal protection system. Sixteen large panels, both flat and contoured, were successfully fabricated and time-studied to develop and refine tooling and manufacturing methods and to establish a realistic baseline for estimating costs. Six of the panels were bonded to a DC-3 airframe. The work included a detailed estimate of fabrication and installation costs.

Norwood, L. B.↗
NASA NTRS1973

Instrumentation for air quality measurements.

Comparison of the new generation of air quality monitoring instruments with some more traditional methods. The first generation of air quality measurement instruments, based on the use of oxidant coulometric cells, nitrogen oxide colorimetry, carbon monoxide infrared analyzers, and other types of detectors, is compared with new techniques now coming into wide use in the air monitoring field and involving the use of chemiluminescent reactions, optical absorption detectors, a refinement of the carbon monoxide infrared analyzer, electrochemical cells based on solid electrolytes, and laser detectors.

Loewenstein, M.↗
NASA NTRS1972

Fast differential thermal analysis.

A study is conducted of the limits of time-dependent differential thermal analysis (DTA). Applications of DTA to the hysteresis phenomena of glasses are also reported. The computation of DTA sample temperatures is discussed, giving attention to feasible heating rates, transient effects to be measured, and the simulation of DTA responses to changes in thermal diffusivity similar to hysteresis phenomena in glasses. The reproducibility of temperature recording is checked with zone-refined organic chemicals.

Wunderlich, B.↗
NASA NTRS1973

A manual-control approach to development of VTOL automatic landing technology.

The operation of VTOL aircraft in the city-center environment will require complex landing-approach trajectories that insure adequate clearance from other traffic and obstructions and provide the most direct routing for efficient operations. As part of a larger program to develop the necessary technology base, a flight investigation was undertaken to study the problems associated with manual and automatic control of steep, decelerating instrument approaches and landings. The study employed a three-cue flight director driven by control laws developed and refined during manual-control studies and subsequently applied to the automatic approach problem. The validity of this approach was demonstrated by performing the first automatic approach and landings to a predetermined spot ever accomplished with a helicopter. The manual-control studies resulted in the development of a constant-attitude deceleration profile and a low-noise navigation system.

Kelly, J. R.↗
NASA NTRS1973

Skylab experience with Apollo docking/latching loads.

Description of the four-year development of Skylab analytical programs, mathematical model complexity, and vibration and load analyses associated with the docking/latching maneuver. Examples are shown where coarse models produced loads in excess of structural capability. However, subsequent model refinement lowered the loads to the point where redesign was not required. A summary of experience gained over a four-year period is presented in the conclusions.

Heath, R. A.↗
NASA NTRS1973

Principles and techniques of polarimetric mapping.

This paper introduces the concept and potential value of polarimetric maps and the techniques for generating these maps in operational remote sensing. The application-oriented polarimetric signature analyses in the literature are compiled, and several optical models are illustrated to bring out requirements of a sensor system for polarimetric mapping. By use of the concepts of Stokes parameters the descriptive specification of one sensor system is refined. The descriptive specification for a multichannel digital photometric-polarimetric mapper is based upon our experience with the present single channel device which includes the generation of polarimetric maps and pictures. High photometric accuracy and stability coupled with fast, accurate digital output has enabled us to overcome the handicap of taking sequential data from the same terrain.

Halajian, J.↗
NASA NTRS1973

Mixed finite-difference scheme for analysis of simply supported thick plates.

A mixed finite-difference scheme is presented for the stress and free vibration analysis of simply supported nonhomogeneous and layered orthotropic thick plates. The analytical formulation is based on the linear, three-dimensional theory of orthotropic elasticity and a Fourier approach is used to reduce the governing equations to six first-order ordinary differential equations in the thickness coordinate. The governing equations possess a symmetric coefficient matrix and are free of derivatives of the elastic characteristics of the plate. In the finite difference discretization two interlacing grids are used for the different fundamental unknowns in such a way as to reduce both the local discretization error and the bandwidth of the resulting finite-difference field equations. Numerical studies are presented for the effects of reducing the interior and boundary discretization errors and of mesh refinement on the accuracy and convergence of solutions. It is shown that the proposed scheme, in addition to a number of other advantages, leads to highly accurate results, even when a small number of finite difference intervals is used.

Noor, A. K.↗