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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 469 records · Page 26
All sourcesNASA NTRSDOE OSTI
NASA NTRS1973

Extended torsional tests of an interlocked bi-stem satellite boom

The effect is reported of continued oscillations of a 1.27-cm interlocked bi-stem satellite boom. The test setup oscillated a boom continuously between set torque limits and periodically recorded its hysteresis characteristics. Results showed that repeated oscillations affected torsional characteristics and that torsional rigidity changed as a function of the number of cycles oscillated within certain torque limits. Torsional characteristics changes caused by repeated oscillations were retained.

Abercrombie, R. A.↗
NASA NTRS1972

The bi-composite transition joint

The application of advanced composite materials to high performance structure frequently results in the desire to fabricate a structure from more than one composite system in order to tailor the composite material capabilities to the design requirements. The bi-composite transition provides a means of joining two different composite structural systems without the weight and complexity of mechanical attachments. The monolayer plies or combinations of plies of one composite system are interleaved with and bonded to the plies of the adjacent composite system, thereby providing a direct load transfer between the two composite structures.

Dullea, K. C., Jr.↗
NASA NTRS1977

Studies of hydride formation and superconductivity in hydrides of alloys Th-M /M = La, Y, Ce, Zr and Bi/

In order to gain a better insight into both the unusual composition of ThH15 and its superconductivity, an experimental study was conducted to assess the influence of partial replacement of Th in Th4H15 by elements which allow for a systematic alteration of spatial and electronic effects. For this purpose, substituent elements with the same number of valence electrons (4) but of smaller size (Zr) as well as elements with a smaller number of valence electrons (3) and either larger (La) or smaller size (Y) were selected. A few data with Ce and Bi as substituent atoms are also included. The matrix alloys for hydriding were obtained by induction melting under Ar in water-cooled Cu boats. Superconducting transition temperatures are found to decrease on substitution for Th in Th4H15. Hydrides derived from LaH3 by substitution for La by Th do not become superconducting. It is suggested that superconductivity in Th4H15 is connected with a deviation from the exact stoichiometry of Th4H15. A model of unsatisfied valencies may be of more general validity in predicting superconductivity.

Oesterreicher, H.↗
NASA NTRS1977

Bi-resampled data study

The results of an experimental study conducted to determine the geometric and radiometric effects of double resampling (bi-resampling) performed on image data in the process of performing map projection transformations are reported.

Benner, R.↗
NASA NTRS1978

Bi-directional, buried-wire skin-friction gage

A compact, nonobtrusive, bi-directional, skin-friction gage was developed to measure the mean shear stress beneath a three-dimensional boundary layer. The gage works by measuring the heat flux from two orthogonal wires embedded in the surface. Such a gage was constructed and its characteristics were determined for different angles of yaw in a calibration experiment in subsonic flow with a Preston tube used as a standard. Sample gages were then used in a fully three-dimensional turbulent boundary layer on a circular cone at high relative incidence, where there were regimes of favorable and adverse pressure gradients and three-dimensional separation. Both the direction and magnitude of skin friction were then obtained on the cone surface.

Higuchi, H.↗
NASA NTRS1980

BI Crucis - A new symbiotic star

A Mount Stromlo spectrogram of BI Cru taken in 1962 shows emission lines of H I, He I, He II, Fe II, N III, and the forbidden O III, forbidden Ne III, and forbidden S II transitions superposed on a weak bluish continuum. A spectrogram by Allen in 1974 shows emission lines of H I and Fe II and possibly weak He I, forbidden Fe II, and forbidden O I lines superposed on an M-star absorption spectrum. The object is evidently a symbiotic star showing large variations in its spectral character. Significant differences exist in the mean ion velocities and appear to be correlated with ionization potential.

Henize, K. G.↗
NASA NTRS1981

Bi-directional communication interface for microprocessor-to-system/370

The design and operation of a bi-directional communication interface between a microcomputer and the IBM System/370 is documented. The hardware unit interconnects a modem to interface to the S/370, the microcomputer with an EIA I/O port, and a terminal for sending and receiving data from either the microcomputer or the S/370. Also described is the software necessary for the two-way interface. This interface is designed so that no modifications need to be made to the terminal, modem, or microcomputer.

Fischer, J. P.↗
NASA NTRS1981

Bi-directional streaming of solar wind electrons greater than 80 eV - ISEE evidence for a closed-field structure within the driver gas of an interplanetary shock

In near time coincidence with the arrival of helium enriched plasma driving the shock wave disturbance of November 12-13, 1978, strong bi-directional streaming of solar wind electrons greater than about 80 eV was observed with Los Alamos instrumentation on ISEE 3. The streaming persisted for many hours simultaneously parallel and anti-parallel to the interplanetary magnetic field which was directed roughly perpendicular to the sun-satellite line. This example of bidirectional streaming cannot be explained by field line connection to the earth's bow shock or the outward propagating interplanetary shock which passed ISEE 3 approximately 16 hours earlier. The event is explained if the local interplanetary field was a part of a magnetic bottle rooted at the sun or a disconnected loop propagating outward.

Bame, S. J.↗
NASA NTRS1981

Momentum and energy exchange collision terms for interpenetrating bi-Maxwellian gases

For application to aeronomy and space physics problems involving strongly magnetized plasma flows, we derived momentum and energy exchange collision terms for interpenetrating bi-Maxwellian gases. Collision terms were derived for Coulomb, Maxwell molecule, and constant collision cross-section interaction potentials. The collision terms are valid for arbitrary flow velocity differences and temperature differences between the interacting gases as well as for arbitrary temperature anisotropies. The collision terms had to be evaluated numerically and the appropriate coefficients are presented in tables. However, the collision terms were also fitted with simplified expressions, the accuracy of which depends on both the interaction potential and the temperature anisotropy. In addition, we derived the closed set of transport equations that are associated with the momentum and energy collision terms.

Barakat, A. R.↗
NASA NTRS1982

Bi-directional communication interface for microprocessor-to-system/370

The design and operation of a bi-directional communication interface between a microcomputer and the IBM System/370 is documented. The hardware unit inter-connects a modem to interface to the S/370, the microcomputer with an EIA I/O port, and a terminal for sending and receiving data from either the microcomputer of the S/370. The software necessary for the two-way interface is also described. This interface was designed so that no modifications need to be made to the terminal, modem or microcomputer.

Fischer, J. P.↗
NASA NTRS1981

OH emission in the direction of TV Gem and BI Cyg

The NRAO-Green Bank 43-m telescope and 18-cm receiver have detected OH maser main-line emission at 1665 MHz, in the direction of the two late-type supergiants TV Gem and BI Cyg. The detection of the two new OH maser sources is noteworthy in view of the small number of late-type supergiants known to be molecular radio sources, or associated in close proximity with OH emission clouds. The IR, UV and radio properties of the two stars are discussed.

Brown, L. W.↗
NASA NTRS1982

Quantiles, parametric-select density estimation, and bi-information parameter estimators

A quantile-based approach to statistical analysis and probability modeling of data is presented which formulates statistical inference problems as functional inference problems in which the parameters to be estimated are density functions. Density estimators can be non-parametric (computed independently of model identified) or parametric-select (approximated by finite parametric models that can provide standard models whose fit can be tested). Exponential models and autoregressive models are approximating densities which can be justified as maximum entropy for respectively the entropy of a probability density and the entropy of a quantile density. Applications of these ideas are outlined to the problems of modeling: (1) univariate data; (2) bivariate data and tests for independence; and (3) two samples and likelihood ratios. It is proposed that bi-information estimation of a density function can be developed by analogy to the problem of identification of regression models.

Parzen, E.↗
NASA NTRS1983

Influence of freezing rate changes of MnBi-Bi eutectic microstructure

In an attempt to explain the influence of space processing on the microstructure of MnBi-Bi, eutectic mixtures were directionally solidified with a sudden change of translation rate. The MnBi fiber spacing was able to adapt to the changing freezing rate as predicted by heat transfer computations. Thus the microstructure adapts more rapidly than the freezing rate could be changed in the present experiments.

Wilcox, W. R.↗