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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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A superconducting microbridge small enough to exhibit the Josephson effect has been shunted by a large external capacitance. Surprisingly little capacitive hysteresis is observed in its I-V characteristic. Prominent subgap structures are seen. The resistively shunted junction (RSJ) model fails to explain the observations.
The disk boundaries of coronal holes have been systematically determined from XUV observations taken during the manned Skylab missions (June 1973-January 1974). The resulting atlas was used to find the sizes, global distributions, differential rotation rates, growth/decay rates and lifetimes of holes during this period. The polar cap holes together covered 15% of the sun's total surface area, a number which remained surprisingly constant throughout Skylab despite the fact that each pole was independently evolving in time. Lower latitude holes contributed another 2 to 5%.
The very low error probability obtained with long error-correcting codes results in a very small number of observed errors in simulation studies of practical size and renders the usual confidence interval techniques inapplicable to the observed error probability. A natural extension of the notion of a 'confidence interval' is made and applied to such determinations of error probability by simulation. An example is included to show the surprisingly great significance of as few as two decoding errors in a very large number of decoding trials.
Narrow-band spectrophotometric observations of HDE 245770 with the multichannel spectrometer and slit spectra obtained with the SIT digital spectrograph at the Cassegrain focus of the 5-m Hale telescope indicate that this star is of spectral type B0 with emission at H-alpha, H-beta, and probably 5876 A of He I. There is some evidence that it is of luminosity class III. The reddening is estimated in various ways and corresponds to a B-V color excess of 0.80. If the star is really a giant, its distance is approximately 1.8 kpc. No variations larger than 1% at the reported 104-x X-ray pulse period are evident in the data in visual magnitude, color, or H-alpha emission intensity. This is not surprising, since the optical star is much more luminous than the X-ray object, and the heating effect of the X-ray source (which is assumed to be one component of a binary) on the B0 star's atmosphere can produce at most a few percent modulation in visual light.
Reforming of organics in aqueous solutions is being investigated as a potential waste treatment process. Earlier studies showed that glucose in water reacts to form a gaseous mixture of CO, H2, CH4, CO2, C2H6, and C2H4 in the vicinity of the critical conditions of water (374 C, 22 MPa). The earlier work has been extended to determine the effect of variations in temperature and feed concentration on the extent of gasification. The percent gasification decreases with increasing feed concentration, indicating an overall kinetic order less than unity. Surprisingly, the percent gasification decreases with increasing temperature. A number of preliminary experiments were conducted with maple sawdust feed, which was thought to be representative of complex organic wastes from paper and vegetable matter. Once again, no solid products were found under the critical conditions; the percent gasification ranged from 16 to 88 percent, depending on the feed composition and residence time.
Analyses of the Apollo-Soyuz science demonstrations on chemical foams and liquid spreading are presented. The chemical foams demonstation showed that aqueous foams and gas/liquid dispersions are more stable in low-g than on the ground. Unique chemical reactions in low-g foams and gas/liquid dispersions are therefore possible. Further ground tests on the formaldehyde clock reaction led to the rather surprising conclusions that surfaces can exert a nucleation effect and that long-range surface influences on chemical reaction rates are apparently operative.
A bounded operator A on a Hilbert space H was positive. These operators were symmetric, and as such constitute a natural generalization of nonnegative real diagonal matrices. The following result is thus both well known and not surprising: A positive operator has a unique positive square root (under operator composition).
Observations of density enhancement in the near corona at solar cycle (sunspot) maximum have rather uncritically been interpreted to apply equally well to the extended corona, thus generating concern about the quality of outer planet navigational data at solar cycle maximum. Spacecraft have been deployed almost continuously during the recently completed solar cycle 20, providing two powerful new coronal investigatory data sources: (1) in-situ spacecraft plasma measurements at approximately 1 AU, and (2) plasma effects on monochromatic spacecraft signals at all signal closest approach points. A comprehensive review of these (solar cycle 20) data lead to the somewhat surprising conclusions that for the region of interest of navigational data, the highest levels of charged particle corruption of navigational data can be expected to occur at solar cycle minimum, rather than solar cycle maximum, as previously believed.
Accreting compact objects may be important gamma ray line sources and may explain recent observations of celestial gamma-ray line emission from a transient source in the direction of the galactic anti-center, from the galactic center, and possibly from the radio galaxy Centaurus A. The identification of the lines from the transient source requires a strong redshift. Such a redshift permits the identification of these lines with the most intense nuclear emission lines expected in nature, positron annihilation, and neutron capture on hydrogen and iron. Their production as a result of nuclear interactions in accreting gas around a neutron star is proposed. The gamma-ray line emission from the galactic center and possibly Centaurus A appears to have a surprisingly high luminosity, amounting to perhaps as much as 10% of the total luminosity of these sources. Such high gamma-ray line emission efficiencies could result from nuclear interactions in accreting gas around a massive black hole.
Observations made by ancient man are of great interest to present day astronomers. Drawings made by neolithic man in caves show a surprising sense of perspective. The discoveries in the Fern Grotto in California are of special interest. Photographs of cave drawings are included.
This study focuses on establishing the sensitivity of predictions of NO production to uncertainties in altitude, reaction rate coefficients, turbulent mixing rates, and Mach disk size and location. The results show that relatively large variations in parameters related to these phenomena had surprisingly little effect on predicted NO production.
Twenty-four millimeter-wave emission lines of ethyl cyanide (CH3CH2CN) have been detected in the Orion Nebula (OMC-1) and seven in Sgr B2. To derive precise radial velocities from the astronomical data, a laboratory measurement of the rotational spectrum of ethyl cyanide has been made at frequencies above 41 GHz. In OMC-1, the rotational temperature of ethyl cyanide is 90 K (in good agreement with other molecules), the local-standard-of-rest radial velocity is 4.5 + or - 1.0 km/s (versus 8.5 km/s for most molecules), and the column density is 1.8 by 10 to the 14th power per sq cm (a surprisingly high figure for a complicated molecule). The high abundance of ethyl cyanide in the Orion Nebula suggests that ethane and perhaps larger saturated hydrocarbons may be common constituents of molecular clouds and have escaped detection only because they are nonpolar or only weakly polar.
It is pointed out that the Viking missions to Mars are the most extraordinary and complex remote effort ever performed by man. Factors which made the Viking results so remarkable are related to the technological engineering accomplishment, the voluminous scientific data about the planet, and the public interest. Quite surprisingly it was found that the Viking 1 landing site was very similar to the California desert. Attention is given to details of spacecraft landing on the Martian surface, aspects of landing site selection, the design and the operation of Lander instruments, the nine different investigations performed by the Lander, the significance of the pictures obtained of Mars, the remarkable heterogeneity of the planet, the extent and variety of volcanism, the presence of water in the solid and gaseous form on the Martian surface, the presence of water in the liquid phase at some time in the past, the two natural Martian satellites, the composition of the Martian polar caps and their changes during the seasons, the composition of the atmosphere, and the biological results, which remain ambiguous.
The ratio of L-alpha to H-alpha is around unity in flares, quasars, and the solar chromosphere and prominences. The weakness of L-alpha is shown to be essentially due to photon trapping and deexcitation, but it is argued that the surprising stability of this ratio is due to the role of these lines in cooling the plasma rather than the accidental parameters used in various models of these widely different phenomena.
Nonaxial thrusts produced by solid rocket motors during three-axis stabilized attitude control have been determined from ascent experience on twenty three Burner II, Burner IIA and Block 5D-1 upper stage vehicles. A data base representing four different rocket motor designs (three spherical and one extended spherical) totaling twenty five three-axis stabilized firings is generated. Solid rocket motor time-varying resultant and lateral side force vector magnitudes, directions and total impulses, and roll torque couple magnitudes, directions, and total impulses are tabulated in the appendix. Population means and three sigma deviations are plotted. Existing applicable ground test side force and roll torque magnitudes and total impulses are evaluated and compared to the above experience data base. Within the spherical motor population, the selected AEDC ground test data consistently underestimated experienced motor side forces, roll torques and total impulses. Within the extended spherical motor population, the selected AEDC test data predicted experienced motor side forces, roll torques, and total impulses, with surprising accuracy considering the very small size of the test and experience populations.
The principal problem in lunar magnetism is to account for the surprisingly large magnitude of the remanent magnetism of lunar surface material. Experiments conducted in this connection have shown that shock is an important mechanism of both magnetization and demagnetization. A description is presented of new experimental results in the low-shock range. An attempt is made to assess the effect of shock upon estimates of the ancient lunar field intensity. The results are used as a basis for a reconsideration of the present lunar field models in the light of intensity estimates and other new results. It is found that the central questions in lunar magnetism have not yet been answered to everyone's satisfaction.
Jupiter's low-frequency radio emission were detected by the planetary radio astronomy instruments onboard the two Voyager spacecraft. The emission is surprisingly similar in morphology but opposite in polarization to the high-frequency Jovian radio noise that were observed with ground-based telescopes for more than two decades. Several possible explanations for the behavior of the low-frequency emission are examined, but none of them is completely satisfactory.
Disturbances such as flap and aileron hinges and poorly faired spoilers were simulated in a computer wind tunnel. The total drag of a single roughness element does not depend only on the size of that element. Its position on the wing has a surprisingly strong effect. In particular, a roughness element on the convex side of a deflected flap or aileron causes a very substantial increase in drag. Very few experimental data are available for comparison. Good agreement with experiment can be achieved, however, by adapting a fictive step size. The correlation between the real roughness-element size and the drag increase remains to be determined. Simple, fundamental experiments are suggested which will allow a theoretical estimation of the drag increase due to roughness elements.