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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 811 records · Page 45
All sourcesNASA NTRSDOE OSTI
NASA NTRS1976

Transient analysis of unbalanced short circuits of the ERDA-NASA 100 kW wind turbine alternator

Unbalanced short-circuit faults on the alternator of the ERDA-NASA Mod-O100-kW experimental wind turbine are studied. For each case, complete solutions for armature, field, and damper-circuit currents; short-circuit torque; and open-phase voltage are derived directly by a mathematical analysis. Formulated results are tabulated. For the Mod-O wind turbine alternator, numerical calculations are given, and results are presented by graphs. Comparisons for significant points among the more important cases are summarized. For these cases the transients are found to be potentially severe. The effect of the alternator neutral-to-ground impedance is evaluated.

Hwang, H. H.↗
NASA NTRS1976

Measurement of the positron-electron reaction which produces a gamma ray pair in the region psi/3684/

An experiment was conducted to measure gamma ray pairs produced in the electron-positron reaction in the region of psi(3684) resonance. The apparatus consisted of two identical spectrometers mounted in a collinear configuration about the beam interaction region. Graphs are presented for the coplanarity angle between reconstructed gamma ray directions, for the scattering and energy deposition of gamma rays in the two crystals used, and for the observed rate of annihilation reactions as a function of center of mass energy.

Hughes, E. B.↗
NASA NTRS1976

Heat flow anomaly associated with dike intrusion. II

An investigation reported by Horai (1974) is continued. A special case of the steady state temperature field associated with dike intrusion is studied, taking into account an infinite vertical downward extension of the isotherm of rectangular shape approximating the dike. The considered case represents a problem of two-dimensional steady state thermal conduction. The technique of conformal mapping used is identical to the method employed by Horai (1974). The characteristics of surface heat flow associated with an infinitesimal thin dike of certain temperature with the considered extension are shown in a graph.

Horai, K.-I.↗
NASA NTRS1976

The effects of forced air flow and oxygen concentration on flammability, smoke density, and pyrolytic toxicity

The question is posed whether forced air flow should be incorporated into flammability tests as a relevant variable. A test apparatus is described which permits tests to be conducted on small test specimens in a forced flow which is (continuously) variable over flow velocities from zero to 300 feet per minute (1.52 m/s). The effects of air-flow rate and oxygen concentration on flame propagation rate, maximum smoke density, and pyrolytic product toxicity were measured for a single material and were statistically evaluated. Regression analysis was used to graph the resulting relationships. It is concluded that air velocity is an important variable for laboratory flammability testing.

Sauers, D. G.↗
NASA NTRS1976

On the response of superpressure balloons to displacements from equilibrium density level

The response of a superpressure balloon to an initial displacement from its constant-density floating level is examined. An approximate solution is obtained to the governing vertical equation of motion for constant-density superpressure balloons. This solution is used to filter out neutrally buoyant oscillations in balloon records despite the nonlinear behavior of the balloon. The graph depicting the pressure data after deconvolution between the raw pressure data and the normalized balloon wavelet shows clearly the strong filtering-out of the neutral buoyancy oscillations.

Levanon, N.↗
NASA NTRS1976

Space Shuttle noise suppression concepts for the Eastern Test Range

The basic objectives of the Space Shuttle noise suppression program for the Eastern Test Range were the definition of the acoustic environment of the Shuttle and the adjacent ground plane for both on-pad and liftoff conditions and the definition of realistic noise suppression techniques and modification of the launch facility that could reduce engine noise associated with supersonic flow. Scaling considerations for acoustic model testing based on the principle of dynamic similarity are detailed. Suppression approaches are described with emphasis placed on barriers and shields: exhaust flow trench covers, solid dividers between the SSME and SRB exhaust flows and a crossed pipe water injection system over the SSME exhaust flow trench. Graphs are presented summarizing noise data gathered for various noise sources and using different suppression approaches.

Guest, S. H.↗
NASA NTRS1976

Explanation for the very low Ga and Ge concentrations in some iron meteorite groups

Parallels between the abundance patterns of moderately volatile elements in iron meteorites and ordinary chondrites are pointed out and discussed in relation to condensation processes in the solar nebula. The discussion is centered around a graph in which As, Cu, Ga, Ge to Ni ratios, normalized to CI chondrites, are compared for IVB, IVA, IVB, and IIIAB irons and H-group ordinary chondrites. The patterns suggest that the same volatile loss mechanism was at work for both IVB irons and ordinary chondrites, but was more efficient in the IVB process. A picture for the process at the IVB location is proposed, according to which condensation occurred when temperature decreased rapidly and trace metals condensed as a fine aerosol that was later blown away by a T-Tauri solar storm. Condensation at the H-group location was more complete because of a less rapid temperature decrease, allowing trace metals to diffuse deeper into Fe-Ni grains. Possible ways in which IVA conditions may have differed from IIIAB or H conditions are also proposed and discussed.

Wasson, J. T.↗
NASA NTRS1976

The effect of adiabatic focusing upon charged-particle propagation in random magnetic fields

The charged particles considered are scattered by random fields while they propagate along the diverging lines of force of a spatially inhomogeneous guiding field. Their longitudinal transport is described in terms of the eigenfunctions of a Sturm-Liouville operator which incorporates the effect of adiabatic focusing along with that of scattering. The relaxation times and characteristic velocities which appear in this matrix formulation of the transport problem are graphed and tabulated. Explicit formulas which describe the particle-density profile that results from a localized impulsive injection are derived for two different regimes. In the first regime, where focusing is relatively weak, a diffusive mode of propagation is dominant, but coherent modes are also present, and they become prominent as the intensity of focusing increases. In the second regime, where focusing is strong and where diffusion does not occur, the propagation is purely coherent. The existence of this supercoherent mode of particle transport opens up many possibilities for the interpretation of astrophysical phenomena.

Earl, J. A.↗
NASA NTRS1976

Blast wave in a nozzle for propulsive applications

The reported investigation has been conducted in connection with studies concerning the development of a propulsion system based on the use of a detonating fluid propellant. Measurements have been made of the pressure and shock wave velocity in a conical nozzle at various ambient pressures and at an ambient temperature of 25 C. In the experiments a small amount of explosive was placed at the end wall of a conical aluminum nozzle and detonated by a microdetonator inside the nozzle. Differences regarding the characteristics of conventional chemical propulsion and detonation propulsion are illustrated with the aid of a graph. One- and two-dimensional numerical flow calculations were performed and compared with the experimental data.

Varsi, G.↗
NASA NTRS1976

Ground state properties of solid and liquid spin-aligned atomic hydrogen

Calculations of the ground state energy in the solid phase were performed with the aid of a variational approach. The Morse potential form of the atomic triple potential computed by Kolos and Wolniewicz (1965) was employed for the calculations. The ground state energies of both the liquid and solid phases of spin-aligned atomic hydrogen around the volume of the transition are presented in a graph.

Danilowicz, R. L.↗
NASA NTRS1975

Magnetospheric plasma regions and boundaries

The boundaries of the various regions of the magnetospheric plasma are considered, taking into account the bow shock, the magnetopause, the outer boundary of the plasma sheet, the inner boundary of the plasma sheet, and the trapping boundary for energetic particles. Attention is given to the steady state, or quasi-steady state, to substorm effects in which temporal changes are important, and to primary auroral processes. A description is presented of the high latitude lobes of the magnetotail. The characteristics of magnetic field topology associated with interconnected interplanetary and geomagnetic field lines are illustrated with the aid of a graph.

Heikkila, W. J.↗
NASA NTRS1976

Analysis of multicircuit shells of revolution by the field method

The reported investigation represents a continuation of studies conducted by Cohen (1974). The current analysis treats a much broader class of connected graphs which may contain multiple circuits. Attention is given to the definition of a boundary-value problem, the field relations, a plan of the field method, differential equations for field functions, initial values of field functions, and shells of revolution.

Cohen, G. A.↗
NASA NTRS1978

Technology of welding aluminum alloys-II

Step-by-step procedures were developed for high integrity manual and machine welding of aluminum alloys. Detailed instructions are given for each step with tables and graphs to specify materials and dimensions. Throughout work sequence, processing procedure designates manufacturing verification points and inspection points.

Source record↗
NASA NTRS1976

The use of LANDSAT DCS and imagery in reservoir management and operation

The author has identified the following significant results. A graph that shows the snow water equivalent data during the 1975-76 winter season for the Ninemile and Michaud Farms snow pillows located in northern Maine is shown. The Bournes transducers used in the snow pillow interface were tested after field use under controlled laboratory conditions of temperature and pressure. It was found that the temperature calibration curve for the Bournes transducers became erratic below 0 C. On 8-10 August 1976, the remainder of hurricane, Belle, travelled through Vermont, New Hampshire, northern Maine, and on into Canada's Maritime Provinces dumping three inches of rain in many areas. In Canada and Maine, local storms dropped up to two inches during the following week. The Saint John River reached near flood stages at Fort Kent, Maine. During this storm, DCP data were received from Fort Kent, Ninemile Bridge, and Saint Francis River in New Brunswick. Resulting high runoff after these storms was studied in connection with the proposed Dickey-Lincoln School dams to be built in that area, and significantly, it was found that creditable flood hydrographs could be generated from LANDSAT DCP data in spite of the voids caused by the satellite being below the horizon.

Cooper, S.↗
NASA NTRS1976

Mated aerodynamic characteristics investigation for the 0.04 scale model TE 1065 (Boeing 747-100) of the 747 CAM and the 0.0405 scale model (43-0) of the space shuttle orbiter in the NASA Langley V/STOL transition research wind tunnel (CA8), volume 1

Aerodynamic force data are presented in tables and graphs for the NASA Langley V/STOL Transition Research Wind Tunnel tests on a 0.04 scale model of the 747 with a 0.0405 scale Orbiter space shuttle. The investigation included the effects of flap setting, stabilizer angle, elevator angle, ground proximity, and Orbiter tailcone fairing. Data were obtained in the pitch plane only. The test was run at M = 0.15, with a dynamic pressure of 35 psf. Six static pressures were measured on each side of the 747 CAM nose to determine the effects of the Orbiter on the 747 airspeed and altitude indicators.

Source record↗
NASA NTRS1976

Free-vibration characteristics of a large split-blanket solar array in a 1-g field

Two methods for studying the free vibration characteristics of a large split blanket solar array in both a 0-g and a 1-g cantilevered configuration are presented. The 0-g configuration corresponds to an in-orbit configuration of the array; the 1-g configuration is a typical ground test configuration. The first method applies the equations of continuum mechanics to determine the mode shapes and frequencies of the array; the second method uses the Rayleigh-Ritz approach. In the Rayleigh-Ritz method the array displacements are represented by string modes and cantilevered beam modes. The results of this investigation are summarized by a series of graphs illustrating the effects of various array parameters on the mode shapes and frequencies of the system. The results of the two methods are also compared in tabular form.

Shaker, F. J.↗
NASA NTRS1977

Supersonic stability and control characteristics of a 0.015 scale model 69-0 of the space shuttle orbiter with forebody RSI modifications in the NASA/LaRC 4-foot UPWT (legs 1 and 2) (LA71A/B)

Investigations are reported for the determination of aerodynamic effects of reducing the thickness of the reusable surface insulation located along the sides of the shuttle orbiter in order to allow weight reduction in the nose region. Six-component aerodynamic force and moment data were obtained at Mach numbers from 1.5 to 4.6 over an angle of attack range from about -1 deg to 28 deg. Additional tests were made over an angle of sideslip range from -6 deg to 6 deg at selected angles of attack. Test results are presented in graph and tables.

Source record↗
NASA NTRS1977

A survey of compiler development aids

A theoretical background was established for the compilation process by dividing it into five phases and explaining the concepts and algorithms that underpin each. The five selected phases were lexical analysis, syntax analysis, semantic analysis, optimization, and code generation. Graph theoretical optimization techniques were presented, and approaches to code generation were described for both one-pass and multipass compilation environments. Following the initial tutorial sections, more than 20 tools that were developed to aid in the process of writing compilers were surveyed. Eight of the more recent compiler development aids were selected for special attention - SIMCMP/STAGE2, LANG-PAK, COGENT, XPL, AED, CWIC, LIS, and JOCIT. The impact of compiler development aids were assessed some of their shortcomings and some of the areas of research currently in progress were inspected.

Buckles, B. P.↗