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  • 1
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    Tribology (1982)
    In:  CASI
    Details
    Publikationsdatum: 2006-04-12
    Beschreibung: The adhesion, friction, and wear properties of materials are reviewed and some of the factors influencing these properties are discussed. The forms of lubrication and types of lubricants will also be discussed.
    Schlagwort(e): MECHANICAL ENGINEERING
    Materialart: NASA. Langley Research Center Advan. Mater. Technol.; p 391-410
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  • 2
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    Incipient failure detection (IFD) of SSME ball bearings (1982)
    In:  CASI
    Details
    Publikationsdatum: 2006-02-14
    Beschreibung: Because of the immense noise background during the operation of a large engine such as the SSME, the relatively low level unique ball bearing signatures were often buried by the overall machine signal. As a result, the most commonly used bearing failure detection technique, pattern recognition using power spectral density (PSD) constructed from the extracted bearing signals, is rendered useless. Data enhancement techniques were carried out by using a HP5451C Fourier Analyzer. The signal was preprocessed by a Digital Audio Crop. DAC-1024I noise cancelling filter in order to estimate the desired signal corrupted by the backgound noise. Reference levels of good bearings were established. Any deviation of bearing signals from these reference levels indicate the incipient bearing failures.
    Schlagwort(e): MECHANICAL ENGINEERING
    Materialart: Alabama Univ. in Huntsville The 1981 NASA(ASEE Summer Fac. Fellowship Program; 20 p
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  • 3
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    Robotic fruit harvester (1982)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Schlagwort(e): MECHANICAL ENGINEERING
    Materialart: NASA Technol. Appl. Team; p 15
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  • 4
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    Report on the Workshop on Intercomparison of Solar UV Irradiance Measurements and Related Instrument Calibration (1983)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: The knowledge of the absolute value of the solar ultraviolet irradiance did not improve very much during the rising phase of the solar cycle 21. The variations associated with the solar rotation period were observed by means of three satellites, namely, the Atmospheric Explorer E (AE-E), Nimbus 7 and the Solar Mesospheric Explorer (SME). Long-term variations related to the solar activity cycle are not well known. Values were deduced during the solar cycle 21 from the AE-E satellite and the rocket program performed by the Laboratory for Atmospheric and Space Physics leading to variations of about a factor of 2 around 150 nm but definitely less than 20 percent beyond 175 nm. Such low level of variation is still masked by the current uncertainties and reproducibility of the observations performed since 1976. The uncertainties of recent observations are reported with their discrepancies. The gaps between the current accuracy goals and the achievements are still very important. The challenge for the next three years is to improve both the accuracy and the precision of future observations at the level of the available irradiance standards and to measure quantitatively long-term variations of the order of a few percent. The main causes of these gaps are identified.
    Schlagwort(e): SOLAR PHYSICS
    Materialart: International Council of Scientific Unions Middle Atmosphere Program. Handbook for MAP, Vol. 8; p 45-51
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  • 5
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    Electrodynamic coupling in magnetically confined stellar X-ray loops (1983)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: The solar coronal complex X-ray structure is now known to involve radiation loops that coincide spatially with the magnetic loops confining the radiating plasma. An effort is presently made to identify primary submodels involved in the global coupling between a mechanical energy reservoir of beta value greater than 1 and a contiguous site of X-ray activity whose beta value is lower than 1. The 'dynamo' model invoked establishes a quantitative connection between mechanical driver properties and the dimensions, field strength, and number density distribution of elemental magnetic loops.
    Schlagwort(e): SOLAR PHYSICS
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  • 6
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    Two-phase turbine staging (1983)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: Two-phase turbines would be useful in Rankine cycles using low-quality or saturated-liquid working fluids. The chief problem is low efficiency due to slip losses in nozzles and due to liquid impact and friction losses in rotors. To raise efficiency, a staging method was tested in which the first stage operated at high speed with low relative liquid velocity, and the second stage recovered the first-stage exit energy. The theoretical efficiency for an experimental turbine operating with Refrigerant-22 was raised from 55 percent to 66 percent, and the measured efficiency was raised from 52 percent to 57 percent.
    Schlagwort(e): MECHANICAL ENGINEERING
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  • 7
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    DOE/NASA Automotive Stirling Engine Project Overview 83 (1983)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: An overview of the DOE/NASA Automotive Stirling Engine Project is presented. The background and objectives of the project are reviewed. Project activities are described and technical progress and status are presented and assessed. Prospects for achieving the objective 30 percent fuel economy improvement are considered good. The key remaining technology issues are primarily related to life, reliability and cost, such as piston rod seals, and low cost heat exchanges. Previously announced in STAR as N83-27924
    Schlagwort(e): MECHANICAL ENGINEERING
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  • 8
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    Interpretation of vector magnetograph data including magneto-optic effects. I - Azimuth angle of the transverse field (1983)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: In this paper, the presence of Faraday rotation in measurements of the orientation of a sunspot's transverse magnetic field is investigated. Using observations obtained with the Marshall Space Flight Center's (MSFC) vector magnetograph, the derived vector magnetic field of a simple, symmetric sunspot is used to calculate the degree of Faraday rotation in the azimuth of the transverse field as a function of wavelength from analytical expressions for the Stokes parameters. These results are then compared with the observed rotation of the field's azimuth which is derived from observations at different wavelengths within the Fe I 5250 A spectral line. From these comparisons, it is found: the observed rotation of the azimuth is simulated to a reasonable degree by the theoretical formulations if the line-formation parameter is varied over the sunspot; these variations are substantiated by the line-intensity data; for the MSFC system, Faraday rotation can be neglected for field strengths less than 1800 G and field inclinations greater than 45 deg; to minimize the effects of Faraday rotation in sunspot umbrae, MSFC magnetograph measurements must be made in the far wings of the Zeeman-sensitive spectral line.
    Schlagwort(e): SOLAR PHYSICS
    Materialart: Solar Physics (ISSN 0038-0938); 88; 51-64
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  • 9
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    Dynamics of a surge observed in the C IV and H alpha lines (1983)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: Time sequences of a surge have been obtained in Active Region 2701 during a coordinated SMY program, on October 2nd, 1980, while the MSDP spectrograph operated in H-alpha at the Meudon Solar Tower and the UVSP spectrometer on SMM observed in the 1548 A C IV resonance line. The cold (H-alpha) and hot (C IV) material follow the same channel, and the event lasts about 10 min in both lines. A good correlation is found between H-alpha and C IV velocities; radial velocities along the surge are in the range 40-60 km/s in both cases. The observations are consistent with the hypothesis that a pressure gradient drives the surge. The H-alpha data seem to indicate the presence of a shock wave in the chromosphere, while the C IV quantities (velocities, accelerations) vary on a very short time scale. Their maxima occur at some locations which could be interpreted as 'pinched' zones.
    Schlagwort(e): SOLAR PHYSICS
    Materialart: Astronomy and Astrophysics (ISSN 0004-6361); 127; 2, No; 337-344
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  • 10
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    Influence of unbalance on the nonlinear dynamical response and stability of flexible rotor-bearing systems (1983)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: In this paper, some of the effects of unbalance on the nonlinear response and stability of flexible rotor-bearing systems is presented from both a theoretical and experimental standpoint. In a linear system, operating above its stability threshold, the amplitude of motion grows exponentially with time and the orbits become unbounded. In an actual system, this is not necessarily the case. The actual amplitudes of motion may be bounded due to various nonlinear effects in the system. These nonlinear effects cause limit cycles of motion. Nonlinear effects are inherent in fluid film bearings and seals. Other contributors to nonlinear effects are shafts, couplings and foundations. In addition to affecting the threshold of stability, the nonlinear effects can cause jump phenomena to occur at not only the critical speeds, but also at stability onset or restabilization speeds.
    Schlagwort(e): MECHANICAL ENGINEERING
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  • 11
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    Differences in the temporal variations of solar UV flux, 10.7-cm solar radio flux, sunspot number, and Ca-K plage data caused by solar rotation and active region evolution (1983)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: Attention is given to two types of temporal variations in the solar UV spectral irradiance caused by solar rotation and active region evolution. It is noted that the first type of dissimilar temporal behavior occurs when concentrations of solar active regions evolve at solar longitudes nearly 180 deg apart. Both the UV observations and modeled UV fluxes based on Ca-K plage data then exhibit pronounced 13-day periodicity, whereas the 10.7-cm solar radio flux and sunspot number exhibit quite dissimilar temporal variations. This type of dissimilarity is related to the modeled UV flux and has a dependence on the solar central meridian distance that is narrower than that for the 10.7-cm radio flux or for sunspot numbers. A second case of marked dissimilarity is seen when major new solar active regions arise and dominate the full-disk fluxes for several rotations. It is found that the strongest peaks in 10.7 cm and sunspot numbers tend to occur on their first rotation, for example, during major dips in the total solar irradiance, whereas the Ca-K plages and UV enhancements peak on the next rotation and then decay more slowly on subsequent rotations.
    Schlagwort(e): SOLAR PHYSICS
    Materialart: Journal of Geophysical Research (ISSN 0148-0227); 88; 9883-988
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  • 12
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    Ceramics potential in automotive powerplants (1983)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: The paper addresses the potential that ceramic materials can play an important role in future automotive powerplants - both advanced heat engines and advanced battery systems. A number of related experimental programs are reviewed including ceramics for gasoline and diesel piston engines, gas turbine and Stirling Engines and sodium-sulfur batteries. A strong integrated program to develop ceramics technology is recommended.
    Schlagwort(e): MECHANICAL ENGINEERING
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  • 13
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    The stability of coronal loops - Finite-length and pressure-profile limits (1983)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: Results are described from a quickly converging, necessary-and-sufficient, MHD-stability test for coronal-loop models. The primary stabilizing influence arises from magnetic line tying at the photosphere, and this end conditions requires a series expansion of possible loop excitations. The stability boundary is shown to quickly approach a limit as the number of terms increases, providing a critical length for the loop in proportion to its transverse magnetic scale. Several models of force-free-field profiles are tested and the stability behavior of a localized current channel, embedded in an external current-free region, is shown to be superior to that of other, broader, current profiles. Pressure-gradient effects, leading to increased or decreased stability, are shown to be amplified by line tying. Long loops must either conduct low net current, or exhibit an axial-field reversal coexisting with a low-pressure core. The limits on stability depend on the magnetic aspect ratio, the plasma-to-magnetic pressure ratio, and the field orientation at the loop edge. Applications of these results to the structure of coronal loops are described.
    Schlagwort(e): SOLAR PHYSICS
    Materialart: Solar Physics (ISSN 0038-0938); 88; 163-177
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  • 14
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    Implications of high-energy neutron observations from solar flares (1983)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: The time-dependent flux of high-energy neutrons discovered from the solar flare of 1980 June 21 provides a new technique for determining the total number and energy spectrum of accelerated protons and nuclei at the sun. The implications of these observations on gamma-ray emission, relativistic electron spectrum and number, proton and electron energy contents, and the location of the interaction region are also examined.
    Schlagwort(e): SOLAR PHYSICS
    Materialart: Astrophysical Journal, Part 2 - Letters to the Editor (ISSN 0004-637X); 273; L41-L45
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  • 15
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    Fluid motions in the solar chromosphere-corona transition region. IV - Mass motions over sunspot umbrae (1983)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Schlagwort(e): SOLAR PHYSICS
    Materialart: Astrophysical Journal, Part 1 (ISSN 0004-637X); 273; 374-380
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  • 16
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    Solar irradiance variations. II - Analysis of the extreme ultraviolet measurements onboard the Atmosphere Explorer E satellite (1983)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: Five of the extreme ultraviolet channels (L-alpha, L-beta, He I, He II, Fe XV) measuring irradiance fluctuations on board the AE-E satellite between 1977 and 1980 have been studied in detail. It is shown that the daily variations correspond very closely to the daily variations in solar radio emission (F10.7), but that the UV data are afflicted with serious and to date unrecognized calibration changes during the period of operation of the instruments. In order to correct for these changes, a statistical analysis is carried out, and a set of corrections to the raw data is suggested. The resulting, now uniform, data are then compared with rocket measurements (L-alpha) and data acquired onboard the AE-C satellite (L-beta). Finally the remaining discrepancies are discussed. After concluding that they are below the overall level of uncertainties, a first-order 10-year run of EUV irradiances derived from F10.7 data is proposed. This estimate includes the ratio of irradiance levels between the maxima of solar cycles 20 and 21 and the intervening minimum.
    Schlagwort(e): SOLAR PHYSICS
    Materialart: Journal of Geophysical Research (ISSN 0148-0227); 88; 9037-905
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  • 17
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    Determining the solar wind speed above active regions using remote radio-wave observations (1983)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: A new technique has made it possible to measure the velocity of portions of the solar wind during its flow outward from the sun. This analysis utilizes spacecraft (ISEE-3) observations of radio emission generated in regions of the solar wind associated with solar active regions. By tracking the source of these radio waves over periods of days, it is possible to measure the motion of the emission regions. Evidence of solar wind acceleration during this outward flow, consistent with theoretical models, has also been obtained.
    Schlagwort(e): SOLAR PHYSICS
    Materialart: Science (ISSN 0036-8075); 222; 506-508
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  • 18
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    Energetic electrons associated with solar radio storms (1982)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Schlagwort(e): SOLAR PHYSICS
    Materialart: Osservatorio Astronomico Solar Radio Storms. Proc. of the 4th CESRA Workshop on Solar Noise Storms; p 320-323
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  • 19
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    Solar radio storms in the hectometer-kilometer wavelength range (1982)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Schlagwort(e): SOLAR PHYSICS
    Materialart: Osservatorio Astronomico Solar Radio Storms. Proc. of the 4th CESRA Workshop on Solar Noise Storms; p 70-88
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  • 20
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    Into mesh lubrication of spur gears with arbitrary offset oil jet. I - For jet velocity less than or equal to gear velocity (1983)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: An analysis was conducted for into mesh oil jet lubrication with an arbitrary offset and inclination angle from the pitch point for the case where the oil jet velocity is equal to or less than pitch line velocity. The analysis includes the case for the oil jet offset from the pitch point in the direction of the pinion and where the oil jet is inclined to intersect the common pitch point. Equations were developed for the minimum oil jet velocity required to impinge on the pinion or gear and the optimum oil jet velocity to obtain the maximum impingement depth.
    Schlagwort(e): MECHANICAL ENGINEERING
    Materialart: ASME; 713-718
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  • 21
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    Solar variability (1982)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: The variability in the total radiant energy flux, or solar irradiance, is discussed. Direct techniques of measuring irradiance, including ground-based, balloon and rocket-borne, and spacecraft-based measurements are compared; the latter type has led to dramatic advances in accuracy since it eliminates the need for corrections for atmospheric absorption. Correlations of the measured irradiance with solar activity are described. Indirect techniques that monitor other solar parameters such as photospheric conditions or the solar diameter are reviewed, and theoretical studies which attempt to interpret the measurements are discussed. Physical mechanisms which can lead to changes in the solar luminosity are addressed, as is global time-dependent modeling of the response of the sun to structural perturbations. Finally, findings from all techniques are summarized, their weak and strong points are assessed, and suggestions for future research are made.
    Schlagwort(e): SOLAR PHYSICS
    Materialart: Comments on Modern Physics; vol. 9
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  • 22
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    Measurement of the rugged invariants of magnetohydrodynamic turbulence in the solar wind (1982)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: Measurements of the total energy, cross helicity, and magnetic helicity of the solar wind at 1, 2.8, and 5 AU are presented. These quantities are the three rugged invariants of three-dimensional ideal incompressible MHD turbulence theory. The theoretical technique for measuring the magnetic helicity from the matrix of two-point correlations is shown. The length scales characterizing the magnetic helicity are found to be equal to or greater than those which characterize the magnetic energy. The magnetic helicity typically lies at scales larger than the magnetic correlation length, consistent with the expectations of the inverse cascade and selective decay hypotheses of three-dimensional MHD turbulence. At smaller scales, the magnetic helicity oscillates in sign. Measurements of the cross helicity are not fully consistent with the usual interpretation in terms of outward propagating Alfvenic functions. Especially during the interval at 5 AU the cross helicity is found to oscillate in sign indicating fluctuations propagating both outward and inward.
    Schlagwort(e): SOLAR PHYSICS
    Materialart: Journal of Geophysical Research; 87; Aug. 1
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  • 23
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    Type II solar radio events observed in the interplanetary medium. I - General characteristics (1982)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: (Previously announced in STAR as N81-15927)
    Schlagwort(e): SOLAR PHYSICS
    Materialart: Solar Physics; 78; May 1982
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  • 24
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    S IV emission-line ratios in the sun (1982)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: New atomic data are presented for transitions between the five lowest levels in S IV, taking into account the fine-structure rates between the individual J levels together with the electron impact mixing rates within the levels. The values are found to differ significantly from previously published values. Using the atomic data, ionic level populations are deduced for a range of electron temperatures and densities. The results are used to calculate theoretical line intensity ratios for S IV. Excellent agreement is found with intensity ratios for a variety of solar features observed with the NRL normal incidence spectrograph on Skylab.
    Schlagwort(e): SOLAR PHYSICS
    Materialart: Astrophysical Journal; vol. 257
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  • 25
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    Solar irradiance variations due to active regions (1982)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: Questions regarding changes in solar irradiance due to activity are important, since such changes may have a significant effect on the earth's climate. Solar irradiance measurements conducted outside the earth's atmosphere and, therefore, not affected by it have become possible by utilizing for such measurements satellites, such as the Nimbus 7 and the Solar Maximum Mission satellite (ACRIM experiment). The present investigation has the objective to show that a combination of sunspots and faculae is capable of representing the observed variations in the values of ACRIM data to a satisfactory degree, given the current level of uncertainties in the ground-based data.
    Schlagwort(e): SOLAR PHYSICS
    Materialart: Astrophysical Journal; vol. 256
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  • 26
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    Adhesion and friction of transition metals in contact with non-metallic hard materials (1982)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: (Previously announced in STAR as N81-28233)
    Schlagwort(e): MECHANICAL ENGINEERING
    Materialart: Wear; 77; Apr. 1
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  • 27
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    Radial variation of the solar wind speed between 1 and 15 AU (1982)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: Pioneer 10 and 11 solar wind speeds measured between 1.4 and 15.2 AU are compared with those of IMP 6, 7, and 8 measured at 1 AU for 90-day intervals centered on six solar radial alignments between 1973 and 1978. The time profile of the solar wind speed undergoes change as the distance from the sun increases, which is due to interaction of adjacent solar wind streams. Speed variations are smaller at greater radial distance and both the highest and lowest speeds disappear as radial distance increases. For periods with extremely high speed solar wind streams, the mean solar wind speed decreases as the distance from the sun increases, which must be due to the disappearance of the highest speeds of the streams with increasing distance. It is concluded that at distances from the sun greater than 30-40 AU, the solar wind behavior may closely resemble that of a radially expanding constant speed plasma.
    Schlagwort(e): SOLAR PHYSICS
    Materialart: Journal of Geophysical Research; 87; Apr. 1
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  • 28
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    Measurement of the profile of solar He I resonance lines (1982)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: The analysis of data obtained by a rocket-borne helium-filled spectrometer employing a curve-of-growth technique in 1977 and 1980 is used in an investigation of the 584-A helium resonance line from the full solar disk. Between 6.5 and 13% of the Gaussian core area was found to be missing through self-reversal. Line widths from 1980 and 1977 were 101 + or - 10 mA and 128 + or - 20 mA full width at half maximum, respectively. No consistent relationship is found between the measured widths and solar activity.
    Schlagwort(e): SOLAR PHYSICS
    Materialart: Journal of Geophysical Research; 87; Mar. 1
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  • 29
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    Long term technology development program (1983)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: In the Advanced Adiabatic Development program, the following technology were identified as critical: piston development for oil-less, adiabatic engine; positive displacement compounding and charge system; experimental evaluation of the preheat concept; combustion system with positive ignition assist; and ceramic manufacturing technology. Of these five areas, ceramic manufacturing technology is the pacing item, and is already being addressed by several organizations. Therefore the four remaining areas need immediate attention. Since the lead time involved in engine development and production is long, this technology development should be done concurrently with the AAD engine development. A four year program is outlined which will simultaneously study these first four areas. This program requires two test rigs; one single cylinder adiabatic engine; and one multicylinder adiabatic turbocompound engine.
    Schlagwort(e): MECHANICAL ENGINEERING
    Materialart: Advan. Automotive Diesel Assessment Program; 7 p
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  • 30
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    A.A.D. engine noise evaluation (1983)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: A critique of the various characteristics of engine design influencing noise and attempts to indicator areas where attention is required to obtain noise acceptable engine for automobiles are discussed. It was concluded that the engine has a potential to be quiet beccause a ion rated speed is chosen. Problems with high gas pressure, the fuel injection pump, and the expander/compressor are discussed.
    Schlagwort(e): MECHANICAL ENGINEERING
    Materialart: Cummins Engine Co., Inc. Advan. Automotive Diesel Assessment Program; 29 p
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  • 31
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    Screw expander for light duty diesel engines (1983)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: Preliminary selection and sizing of a positive displacement screw compressor-expander subsystem for a light-duty adiabatic diesel engine; development of a mathematical model to describe overall efficiencies for the screw compressor and expander; simulation of operation to establish overall efficiency for a range of design parameters and at given engine operating points; simulation to establish potential net power output at light-duty diesel operating points; analytical determination of mass moments of inertia for the rotors and inertia of the compressor-expander subsystem; and preparation of engineering layout drawings of the compressor and expander are discussed. As a result of this work, it was concluded that the screw compressor and expander designed for light-duty diesel engine applications are viable alternatives to turbo-compound systems, with acceptable efficiencies for both units, and only a moderate effect on the transient response.
    Schlagwort(e): MECHANICAL ENGINEERING
    Materialart: Cummins Engine Co., Inc. Advan. Automotive Diesel Assessment Program; 46 p
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  • 32
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    Thermal and mechanical analysis of major components for the advanced adiabatic diesel engine (1983)
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    Publikationsdatum: 2011-08-19
    Beschreibung: The proposed design for the light duty diesel is an in-line four cylinder spark assisted diesel engine mounted transversely in the front of the vehicle. The engine has a one piece cylinder head, with one intake valve and one exhaust valve per cylinder. A flat topped piston is used with a cylindrical combustion chamber recessed into the cylinder head directly under the exhaust valve. A single ceramic insert is cast into the cylinder head to insulate both the combustion chamber and the exhaust port. A similar ceramic insert is cast into the head to insulate the intake port. A ceramic faceplate is pressed into the combustion face of the head to insulate the face of the head from hot combustion gas. The valve seats are machined directly into the ceramic faceplate for the intake valve and into the ceramic exhaust pot insert for the exhaust valve. Additional ceramic applications in the head are the use of ceramic valve guides and ceramic insulated valves. The ceramic valve guides are press fit into the head and are used for increased wear resistance. The ceramic insulated valves are conventional valves with the valve faces plasma spray coated with ceramic for insulation.
    Schlagwort(e): MECHANICAL ENGINEERING
    Materialart: Advan. Automotive Diesel Assessment Program; 65 p
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  • 33
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    Advanced automotive diesel engine system study (1983)
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    Publikationsdatum: 2011-08-19
    Beschreibung: A conceptual study of an advanced automotive diesel engine is discussed. The engine concept selected for vehicle installation was a supercharged 1.4 liter, 4 cylinder spark assisted diesel of 14:1 compression ratio. A compounding unit consisting of a Lysholm compressor and expander is connected to the engine crankshaft by a belt drive. The inlet air charge is heated by the expander exhaust gas via a heat exchanger. Four levels of technology achievement on the selected engine concept were evaluated, from state-of-the-art to the ideal case. This resulted in the fuel economy increasing from 53.2 mpg to 81.7 mpg, and the 0-60 mph time decreasing from 17.6 seconds to 10.9 seconds.
    Schlagwort(e): MECHANICAL ENGINEERING
    Materialart: Cummins Engine Co., Inc. Advan. Automotive Diesel Assessment Program; 18 p
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  • 34
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    A study of the Armstrong Whitworth swing beam engine for automotive application (1983)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: The introduction of ceramics to those parts suffering high thermal loading was successfully demonstrated, and there is no question that the 100 kw (134 hp) naturally aspirated engine of the future will be developed to produce up to 300 kw (402 hp) by the application of turbocharging or its equivalent. However, at the 60 - 80 kw (80 - 107 hp) size needed for the economic automotive engine, scaling down the 300 kw (402 hp) is beset by the laws of scale. The conventional four stroke diesel was not shown to be successful at the small high speed engine size. The opposed piston two stroke engine does not suffer the same laws of scale and engines in the low power range have already been marketed successfully. The half liter/cylinder Armstrong Whitworth Swing Beam Engine is the latest to be designed with the automotive market in mind. Its low noise structure and balanced linkage system coupled with advantages for easy start and potential use of low grade fuels, derived from its variable compression ratio and slow piston motion, qualifies it for the application.
    Schlagwort(e): MECHANICAL ENGINEERING
    Materialart: Cummins Engine Co., Inc. Advan. Automotive Diesel Assessment Program; 3 p
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  • 35
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    Roller crosshead analysis (1983)
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    Publikationsdatum: 2011-08-19
    Beschreibung: An analysis of the frictional behavior of a roller crosshead configuration is given. This configuration consists of a piston which carries at the wristpin position a roller of large diameter which can roll on the cylinder liner surfaces. A preliminary assessment is given of whether the roller can roll on the cylinder liner without skidding, and what, if any, are the tribological implications of this approach to a dry lubricated design. The rotational speed of the roller must change during the stroke if it is not to slip on the cylinder liner. The maximum value of angular acceleration occurs at top dead center and bottom dead center. If the traction force on the rim of the roller, which is the product of the normal force due to piston side load and the coefficient of friction, is not sufficient to drive the roller through the necessary angular acceleration, sliding will occur. At 1,000 rpm, it appears that there will be a definite area of slip near each end of the stroke. The length of the area of slip may be of the order of 1/8 inch at each of these points.
    Schlagwort(e): MECHANICAL ENGINEERING
    Materialart: Advan. Automotive Diesel Assessment Program; 9 p
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  • 36
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    Advanced Automotive Diesel Assessment Program, executive summary (1983)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: The objectives of this analytical study were: to select one advanced automotive diesel engine (AAD) concept which would increase the tank mileage of a 3,000 pound passenger car from the present 35 mpg to at least 52 mpg; to identify long term component research and development work required to bring the selected concept to fruition; and to prepare a development strategy that will bring the selected concept to a prototype testing phase. Cummins Engine Company has completed this study. The selected concept is a 4 stroke cycle, direct injection, spark assisted, advanced adiabatic diesel engine with positive displacement compounding plus expander and part load air preheating. The engine does not use a liquid coolant nor liquid lubricants. It is a 4 cylinder, in-line, 77 mm bore x 77 mm stroke, 1.434 liters displacement engine weighing 300 lb, and rated at 70 BHP at 3000 rpm. Installation dimensions are 621 mm length x 589 mm width x 479 mm height (24.4 inch x 22 inch x 18.9 inch).
    Schlagwort(e): MECHANICAL ENGINEERING
    Materialart: Advan. Automotive Diesel Assessment Program p; 59 p
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  • 37
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    Detailed performance analysis of the A.A.D. - concept B (1983)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: New concepts for engine performance improvement are seen through the adoption of heat regeneration techniques; advanced methods to enhance the combustion; and higher efficiency air handling machinery, such as the positive displacement helical screw expander and compressor. Each of these concepts plays a particular role in engine performance improvement. First regeneration has a great potential for achieving higher engine thermal efficiency through the recovery of waste energy. Although the concept itself is not new (this technique is used in the gas turbine), the application to reciprocating internal combustion engines is quite unusual and presents conceptual difficulties. The second important area is better control of the combustion process in terms of heat transfer characteristics, combustion products, and heat release rate. The third area for performance improvement is in the adoption of high efficiency air handling machinery. In particular, positive displacement helical expander and compressor exhibit an extremely high efficiency over a wide range of operating conditions.
    Schlagwort(e): MECHANICAL ENGINEERING
    Materialart: Advan. Automotive Diesel Assessment Program; 46 p
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  • 38
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    Hydromagnetic waves, turbulence, and collisionless processes in the interplanetary medium (1983)
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    Publikationsdatum: 2011-08-18
    Beschreibung: An extended discussion is conducted concerning the origin and evolution of interplanetary hydromagnetic waves and turbulence, and their influence on the large scale dynamics of the solar wind. The solar wind is at present the preeminent medium for the study of hydromagnetic waves and turbulence, providing an opportunity for advancement of understanding of the most fundamental processes of the astrophysical plasmas. All interplanetary fluctuations whose time scale is observed to be greater than 1 sec can be regarded as hydromagnetic fluctuations. It has been found to be simplest, and generally very satisfactory, to model interplanetary variations as fluctuations in an MHD fluid. Attention is given to the classification of wave modes, geometrical hydromagnetics, Alfven wave pressure, rugged invariants, and the kinetic theory of collisionless processes.
    Schlagwort(e): SOLAR PHYSICS
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  • 39
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    Fluid motions the solar chromosphere-corona transition region. II Active region flows in C IV from narrow slit Dopplergrams (1982)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Schlagwort(e): SOLAR PHYSICS
    Materialart: Astrophysical Journal; vol. 261
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  • 40
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    Bonding procedure for Teflon seals (1982)
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    Publikationsdatum: 2011-08-18
    Beschreibung: Material and bonding procedures designed for use as seals at the National Transonic Facility at the NASA Langley Research Center are presented. Teflon TFE was chosen for its ability to withstand pressures of up to 130 psi and temperatures ranging from -320 to 150 F, in addition to tolerances of 0.074 in. and having a movement allowance of 0.75 in. during transient cycles. Since some of the seals are 14 in. in diameter, Teflon sheets had to be sliced and bonded together after machining to size, resulting in seals with circular, oval, straight, and rectangular cross sections. Step-by-step preparation procedures are provided, and it is noted that the scarf joints performed as predicted during tests.
    Schlagwort(e): MECHANICAL ENGINEERING
    Materialart: Astronautics and Aeronautics; 20; Sept
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  • 41
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    Mass motions in the solar chromosphere and transition zone (1982)
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    Publikationsdatum: 2011-08-18
    Beschreibung: A comparison is made between H-alpha and C IV observations of Active Region 2717 on October 9, 1980. On the basis of this comparison, it is found that upward velocities are present above sunspots in the chromosphere-corona transition zone (20 km/s). The downward velocities are found to be well correlated in both lines. Doppler-shift ratios between C IV and H-alpha levels (approximately 10) are seen to be much smaller than expected from density ratio estimates. The comparison is seen as suggesting that flow lines are probably far from vertical in the transition zone. It is pointed out, however, that this depends on model densities that may not be correct. A simple method for comparing matter flows is presented. The best fit between H-alpha and C IV levels is obtained when C IV Doppler shifts are multiplied by the line intensity to the power 0.5 (approximately) in order to make allowance for density fluctuations.
    Schlagwort(e): SOLAR PHYSICS
    Materialart: Astronomy and Astrophysics; 111; 1, Ju; July 198
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  • 42
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    The solar spectrum of O IV, including photoexcitation by Fe IX 171.07 A (1982)
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    Publikationsdatum: 2011-08-18
    Beschreibung: The extreme and far ultraviolet doublet spectrum of O IV, emitted from the solar transition region, is calculated taking account of expected photo-excitation by Fe IX at the wavelength 171.07 A. Four multiplets are shown to be sensitive to such photoexcitation, of which two in particular are potentially observable and could provide an estimate of the local Fe IX radiation field.
    Schlagwort(e): SOLAR PHYSICS
    Materialart: Astronomy and Astrophysics; 108; 2, Ap; Apr. 198
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    Spatial and temporal evolution of soft and hard X-ray emission in a solar flare (1982)
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    Publikationsdatum: 2011-08-18
    Beschreibung: Hard X-ray burst spectrometer and imaging spectrometer data are used to study the spatial and temporal characteristics of the 3.5-30.0 keV emission in an Apr. 10, 1980 solar flare. It is found that: (1) continuous energy release is needed to sustain the increase of the emission through the flare's rising phase, before and after the impulsive phase in hard X-rays, and the release is characterized by the production of 50 million-150 million K thermal regions within the flare loop structures; (2) the observational parameters which characterize the impulsive burst indicate that it is probably associated with nonthermal processes, such as particle acceleration; and (3) the continuous energy release is associated with strong chromospheric evaporation, in view of spectral line behavior. Both particle acceleration and chromospheric evaporation stop just before flare maximum, and the subsequent evolution is probably governed by the radiative cooling of the flare plasma.
    Schlagwort(e): SOLAR PHYSICS
    Materialart: Solar Physics; 79; July 198
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  • 44
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    The solar O III spectrum. I - Photoexcitation of EUV lines by He II Lyman-alpha (1982)
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    Publikationsdatum: 2011-08-18
    Schlagwort(e): SOLAR PHYSICS
    Materialart: Astrophysical Journal; vol. 257
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  • 45
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    Statistical properties of MHD fluctuations associated with high-speed streams from Helios-2 observations (1982)
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    Publikationsdatum: 2011-08-18
    Beschreibung: (Previously announced in STAR as N82-18117)
    Schlagwort(e): SOLAR PHYSICS
    Materialart: Solar Physics; 78; June 198
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  • 46
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    Latest rocket measurements of the solar constant (1982)
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    Publikationsdatum: 2011-08-18
    Beschreibung: Three rocket flights which carried a payload of absolute radiometers to measure the solar constant with an accuracy of plus or minus 0.5 per cent have been accomplished. Several of the rocket radiometers were duplicates of those aboard the Solar Maximum Mission and Nimbus spacecrafts. The values for the solar constant obtained by the rocket sensors for the three flight dates indicate an increase between the first and latter two flights approximately equivalent to the uncertainty of the measurements. The values for the solar constant for the three flights are 1367, 1372 and 1374 W/sq m.
    Schlagwort(e): SOLAR PHYSICS
    Materialart: Solar Energy; 28; 5, 19; 1982
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  • 47
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    Solar irradiance variations and solar activity (1982)
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    Publikationsdatum: 2011-08-18
    Beschreibung: A mean value for the 1 AU total solar irradiance of 1368.2 W/sq m and a downward trend of 0.05% per year were derived from measurements by the Active Cavity Radiometer Irradiance Monitor (ACRIM) experiment on the Solar Maximum Mission during 1980. Distinct temporary solar irradiance decreases associated with solar activity maxima were observed with a series of nine dips from April to October recurring at fairly regular intervals averaging 24 days. The decreases correlate inversely with sunspot area, 2800-MHz flux, and Zurich sunspot number. Dominant periods common to the irradiance and sunspot area power spectra link the irradiance decreases to sunspot flux deficit in solar active regions. Evidence of significant total irradiance modulation by facular flux excess is cited. A persistent radiative cycle of active regions consistent with the ACRIM irradiance results and the morphology of solar active regions was found. The pattern of regularly recurrent active region maxima between April and October suggests an asymmetry in solar activity generation during this period.
    Schlagwort(e): SOLAR PHYSICS
    Materialart: Journal of Geophysical Research; 87; June 1
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  • 48
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    Solar transition region response to variations in the heating rate (1982)
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    Publikationsdatum: 2011-08-18
    Beschreibung: The response of a numerical model for the upper chromosphere, transition region, and corona to variations in the energy input has been examined. The numerical model solves the set of one-dimensional two-fluid hydrodynamic equations in a simple vertical magnetic flux tube. The atmosphere responds to both the increase and decrease in energy deposition by smoothly readjusting the temperature gradient and the amount of material in the region of peak radiating efficiency to radiate away energy being deposited. At no time during this readjustment is a departure from a thin laminar transition region structure seen. In addition, a time-dependent description of the nonequilibrium ionization of all of the ionization stages of oxygen has been included. This calculation is coupled with the self-consistent calculations of the dynamical variables. It is found that the nonequilibrium ionization balance calculations for both heating and cooling small loops in the quiet sun predict relative ionic abundances which differ substantially from those which would be predicted by an equilibrium calculation
    Schlagwort(e): SOLAR PHYSICS
    Materialart: Astrophysical Journal; vol. 255
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  • 49
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    Doppler wavelength shifts of ultraviolet spectral lines in solar active regions (1982)
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    Publikationsdatum: 2011-08-18
    Beschreibung: Doppler shifts are measured for solar UV emission lines formed in the lower transition region of active regions. Doppler shifts in different regions at the same solar location, variations of Doppler shift with position of an active region on the disk, and variations of Doppler shift with time at the same solar location in the same active region were studied. Observations were made with the NRL slit spectrograph on Skylab. Excluding flare and flare-related phenomena, only redshifts are found whose magnitudes correspond to downflow velocities between about 4 and 17 km/s. Shifts are largest for lines formed between about 50,000 and 100,000 K, and are distinctly less for lines formed above 100,000 K. The shifts persist out to the limb, but not above it. There is no obvious change in redshift for lines measured at the same solar location over time intervals of about 20 minutes.
    Schlagwort(e): SOLAR PHYSICS
    Materialart: Astrophysical Journal; vol. 255
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  • 50
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    Ultraviolet continuum absorption /less than about 1000 A/ above the quiet sun transition region (1982)
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    Publikationsdatum: 2011-08-18
    Beschreibung: Lyman continuum absorption shortward of 912 A in the quiet sun solar transition region is investigated by combining spectra obtained from the Apollo Telescope Mount experiments on Skylab. The most recent atomic data are used to compute line intensities for lines that fall on both sides of the Lyman limit. Lines of O III, O IV, O V, and S IV are considered. The computed intensity ratios of most lines from O IV, O V, and S IV agree with the experimental ratios to within a factor of 2. However, the discrepancies show no apparent wavelength dependence. From this fact, it is concluded that at least part of the discrepancy between theory and observation for lines of these ions can be accounted for by uncertainties in instrumental calibration and atomic data. However, difficulties remain in reconciling observation and theory, particularly for lines of O III, and one line of S IV. The other recent results of Schmahl and Orrall (1979) are also discussed in terms of newer atomic data.
    Schlagwort(e): SOLAR PHYSICS
    Materialart: Astrophysical Journal; vol. 254
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  • 51
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    The condensational instability in the solar transition region and corona (1982)
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    Publikationsdatum: 2011-08-18
    Beschreibung: The stability of plasmas at temperatures and densities typical of the solar transition region and corona is investigated using both a linear analysis and nonlinear time-dependent numerical simulations. Growth rates, decay rates, and oscillation frequencies of the perturbations determined from the linear analysis are in excellent agreement with the simulations. The nonlinear regime is characterized by a bifurcation of the plasma into a cool dense condensation surrounded by a hot tenuous corona. The condensation may then be accelerated by forces in the plasma such as those arising from gravity or differential heating. Finally, the results of the detailed simulation show that the transition region is a dynamically stable structure which is the result of the nonlinear evolution of the condensational instability.
    Schlagwort(e): SOLAR PHYSICS
    Materialart: Astrophysical Journal; vol. 254
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  • 52
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    Transition region oscillations in sunspots (1982)
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    Publikationsdatum: 2011-08-18
    Beschreibung: Time series observations of the profile of the C IV resonance line 1548.19 A obtained in eight sunspots with the Ultraviolet Spectrometer and Polarimeter (UVSP) on the Solar Maximum Mission are discussed. All of the sunspots exhibit significant oscillations in line-of-sight velocity with frequencies in the range from 5.8 mHz to 7.8 mHz (periods of 129-173 s). Significant intensity oscillations are observed at the same periods in four of the time series; the maximum intensity is in phase with maximum blueshift. Difference spectroheliograms ('Dopplergrams') of the two halves of the C IV line, as well as observations in the Si IV resonance line 1402.77 A and the O IV intersystem line 1401.16 A, also reveal velocity oscillations at similar frequencies but only over sunspots.
    Schlagwort(e): SOLAR PHYSICS
    Materialart: Astrophysical Journal; vol. 253
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  • 53
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    The vertical filamentary structures of quiescent prominences (1982)
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    Publikationsdatum: 2011-08-18
    Beschreibung: The thin vertical filaments making up the quiescent prominence plasma, as revealed by fine spatial resolution H-alpha photographs, are characterized by a magnetostatic theory in which a horizontal row of long vertical filaments whose weights are supported by bowed magnetic field lines is described by a class of exact equilibrium solutions. The Kippenhahn-Schlueter (1957) solution for a long sheet without filamentary structures is a member of this class of solutions. In illustrating the role of the magnetic field in supporting and thermally shielding the filament plasma, it is found that the filament can have a sharp transition perpendicular to the local field, while the transition in the direction of the local field is diffuse. A consequence of the filamentary structure is that its support by the Lorentz force requires the electric current to have a component along the magnetic field.
    Schlagwort(e): SOLAR PHYSICS
    Materialart: Solar Physics; 75; Jan. 198
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  • 54
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    Behavior of transition-region lines during impulsive solar flares (1983)
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    Publikationsdatum: 2011-08-18
    Beschreibung: The emissions observed in lines originating in the transition-region plasma, particularly during impulsive flares, are investigated using data collected by the Ultraviolet Spectrometer and Polarimeter on the Solar Maximum Mission. Data concerning lines from ions such as Si II, C IV, Si IV, O V, and Fe XXI are analyzed. Topics examined include the transition region away from sunspots, oscillatory motions above sunspots, the shape of the transition region, the transition region during flares, and O V and Fe XXI during flare flash phases.
    Schlagwort(e): SOLAR PHYSICS
    Materialart: (ISSN 0038-0938)
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  • 55
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    Gamma-ray lines and neutrons from solar flares (1983)
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    Publikationsdatum: 2011-08-18
    Beschreibung: The energy spectrum of accelerated protons and nuclei at the site of a limb flare was derived by a technique, using observations of the time dependent flux of high energy neutrons at the earth. This energy spectrum is very similar to the energy spectra of 7 disk flares for which the accelerated particle spectra was previously derived using observations of 4 to 7 MeV to 2.223 MeV fluence ratios. The implied spectra for all of these flares are too steep to produce any significant amount of radiation from pi meson decay. It is suggested that the observed 10 MeV gamma rays from the flare are bremsstrahlung of relativistic electrons. Previously announced in STAR as N83-19695
    Schlagwort(e): SOLAR PHYSICS
    Materialart: (ISSN 0038-0938)
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    A comparison of coronal and interplanetary current sheet inclinations (1983)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: The HAO white light K-coronameter observations show that the inclination of the heliospheric current sheet at the base of the corona can be both large (nearly vertical with respect to the solar equator) or small during Cararington rotations 1660 - 1666 and even on a single solar rotation. Voyager 1 and 2 magnetic field observations of crossing of the heliospheric current sheet at distances from the sun of 1.4 and 2.8 AU. Two cases are considered, one in which the corresponding coronameter data indicate a nearly vertical (north-south) current sheet and another in which a nearly horizontal, near equatorial current sheet is indicated. For the crossings of the vertical current sheet, a variance analysis based on hour averages of the magnetic field data gave a minimum variance direction consistent with a steep inclination. The horizontal current sheet was observed by Voyager as a region of mixed polarity and low speeds lasting several days, consistent with multiple crossings of a horizontal but irregular and fluctuating current sheet at 1.4 AU. However, variance analysis of individual current sheet crossings in this interval using 1.92 see averages did not give minimum variance directions consistent with a horizontal current sheet. Previously announced in STAR as N83-31566
    Schlagwort(e): SOLAR PHYSICS
    Materialart: Journal of Geophysical Research (ISSN 0148-0227); 88; Oct. 1
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  • 57
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    Practical small-scale explosive seam welding (1983)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: A small-scale explosive seam welding process has been developed that can significantly contribute to remote metal joining operations under hazardous or inaccessible conditions, such as nuclear reactor repair and assembly of structure in space. This paper describes this explosive seam welding process in terms of joining principles, variables, types of joints created, capabilities, and applications. Very small quantities of explosive in a ribbon configuration are used to create narrow (less than 0.5 inch), long-length, uniform, hermetically sealed joints that exhibit parent metal properties in a wide variety of metals, alloys, and combinations. The practicality of this process has been demonstrated by its current acceptance, as well as its capabilities that are superior in many applications to the universally accepted joining processes, such as mechanical fasteners, fusion and resistance welding, and adhesives. Previously announced in STAR as N83-24896
    Schlagwort(e): MECHANICAL ENGINEERING
    Materialart: (ISSN 0025-6501)
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  • 58
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    The solar O III spectrum. II - Longer wavelengths, line widths, and the He II Lyman alpha radiation field (1983)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: The solar O III spectrum above 900 A is analyzed, including several visible and infrared lines which are important in nebular studies. The dependence of the line intensities on the rate of photoexcitation by He Ly-alpha is determined, and the observability of these lines in the solar spectrum is studied. The impact approximation is employed to calculate the expected line widths of the stronger solar O III lines. The photoexciting field at 304 A calculated from the observed intensities of the O III lines below 900 A (Bhatia et al., 1982) is compared with the field predicted by a recent model (Avrett et al., 1976). It is shown that additional radiation trapping must be present beyond that given by this model.
    Schlagwort(e): SOLAR PHYSICS
    Materialart: Astrophysical Journal Supplement Series (ISSN 0067-0049); 53; Sept
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  • 59
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    Measurements on a shock wave generated by a solar flare (1983)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: It is shown that path-integrated radio-scattering measurements of the solar wind velocity yield higher estimates than those of point measurements. The post-shock speed is determined from radio scattering measurements by selection of the maximum of the radio-scattering deduced from the velocity-time curve, whereas velocity points on the rising edge of the shock underestimate the post-shock gas velocity, and therefore the shock speed. However, it is suggested that large uncertainties reside in using radio techniques for measurements of parameters of the shock wave, and the uncertainties may be large enough to encompass the lower velocity values calculated by a point method of measurement.
    Schlagwort(e): SOLAR PHYSICS
    Materialart: Nature (ISSN 0028-0836); 304; Aug. 25
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  • 60
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    Solar radius change between 1925 and 1979 (1983)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: From an analysis of numerous reports from different locations on the duration of totality of the solar eclipses on January 24, 1925, and February 26, 1979, it is found that the solar radius at the earlier date was 0.5 arcsec (or 375 km) larger than at the later date. The correction to the standard solar radius found for each eclipse is different when different subsets of the observations are used (for example, edge of path of totality timings compared with central timings). This is seen as suggesting the existence of systematic inaccuracies in our knowledge of the lunar figure. The differences between the corrections for both eclipses, however, are very similar for all subsets considered, indicating that changes of the solar size may be reliably inferred despite the existence of the lunar figure errors so long as there is proper consideration of the distribution of the observations. These results are regarded as strong evidence in support of the occurrence of solar radius changes on shorter than evolutionary time scales.
    Schlagwort(e): SOLAR PHYSICS
    Materialart: Nature (ISSN 0028-0836); 304; Aug. 11
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  • 61
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    Solar oscillations with 13-day period (1983)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: Reference is made to the solar observations made by Claverie et al. (1982) over a three-month period in the summer of 1981 which show oscillatory velocity with a period of 13.1 days and amplitude of 6.6 m/s. These investigators reject the possibility that they see the Doppler shift from a radial oscillation, because the amplitude is implausibly large. They also do not believe that their signal was induced by solar magnetic fields, since typical mean solar fields are too small. Photo-electric drift-scan measurements of the solar diameter and full-disk magnetograms taken at Kitt Peak National Observatory are examined here for evidence of variations corresponding to the velocity oscillations of the 13.1-day period. An upper limit on radius variations is reported which is a factor of six below the amplitude needed to explain the velocity observations as a radial oscillation. Attention is also given to the possible role of the rotation of large-scale surface magnetic features.
    Schlagwort(e): SOLAR PHYSICS
    Materialart: Nature (ISSN 0028-0836); 304; Aug. 11
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  • 62
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    Formation of the Cl I line at 1351 A in the solar chromosphere (1983)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: The formation of the multiplet containing the Cl I 1351 A line is investigated due to the unusual brightness of this line. It is determined that this line is formed via a fluorescence effect driven by the 1335 A line of C II. Non-LTE calculations including this effect are found to agree with the observed line intensity. It is shown that the 1347 and 1363 A lines of Cl I do not benefit from this effect and they are predicted to be approximately 100 times weaker.
    Schlagwort(e): SOLAR PHYSICS
    Materialart: Astrophysical Journal; vol. 266
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  • 63
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    Observations of solar oscillations of low and intermediate degree (1983)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: Measurements are presented of solar velocity oscillations with spherical harmonic degree 1-139 and angular order approximately 0. With an amplitude sensitivity of approximately 2 cm/s, trapped acoustic wave modes of radial orders 2-26 are observed at frequencies between 1.7 and 5.5 mHz. The radial order identifications of low-degree modes previously inferred from theory are confirmed. Only marginal evidence of long-period, gravity-mode oscillations is found.
    Schlagwort(e): SOLAR PHYSICS
    Materialart: Nature; 302; Mar. 3
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  • 64
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    Magnetic canopies in unipolar regions (1983)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: Base-height statistics are presented for magnetic canopies in six unipolar magnetic regions which were observed near the limb with the Kitt Peak Vacuum Telescope and Diode Array Magnetograph during the period 25 April-3 July, 1980. As in earlier studies, extensive areas are found to be covered by low-lying canopies.
    Schlagwort(e): SOLAR PHYSICS
    Materialart: Solar Physics (ISSN 0038-0938); 87; Aug. 198
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  • 65
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    Corotating pressure waves without fast streams in the solar wind (1983)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: Voyager 1 and 2 magnetic field and plasma data are presented which demonstrate the existence of large scale, corotating, non-linear pressure waves between 2 AU and 4 AU that are not accompanied by fast streams. The pressure waves are presumed to be generated by corotating streams near the sun. For two of the three pressure waves that are discussed, the absence of a stream is probably a real, physical effect, viz., a consequence of deceleration of the stream by the associated compression wave. For the third pressure wave, the apparent absence of a stream may be a geometrical effect; it is likely that the stream was at latitudes just above those of the spacecraft, while the associated shocks and compression wave extended over a broader range of latitudes so that they could be observed by the spacecraft. It is suggested that the development of large-scale non-linear pressure waves at the expense of the kinetic energy of streams produces a qualitative change in the solar wind in the outer heliosphere. Within a few AU the quasi-stationary solar wind structure is determined by corotating streams whose structure is determined by the boundary conditions near the sun. Previously announced in STAR as N83-19694
    Schlagwort(e): SOLAR PHYSICS
    Materialart: Journal of Geophysical Research (ISSN 0148-0227); 88; Aug. 1
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  • 66
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    A surge observed in H alpha and C IV (1982)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: Results are presented of simultaneous measurements of H-alpha (MSDP at Meudon) and C IV (UVSP onboard SMM) of Active Region 2701 made on October 2, 1980. Isodensity and velocity maps were obtained for both lines and these maps were superimposed. Results show a good correlation between the H-alpha and C IV velocities with a surge being observed for 10 minutes. The base of the surge was determined to be located in a bright point in C IV and H-alpha, while the escaping matter followed the same channel ('absorbing' in H-alpha, 'emitting' in C IV). It was found that the velocity along the surge was about 80 km/s in H-alpha and 100 km/s in C IV. In addition, a loop appeared in C IV during the surge. It is concluded that the vertical pressure gradient was capable of driving the surge.
    Schlagwort(e): SOLAR PHYSICS
    Materialart: (ISSN 0273-1177)
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  • 67
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    About the onsets of closely-consecutive homologous flares (1982)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: The onsets of closely consecutive homologous flares (CCHF), which are separated by less than 6 hours and most often by about 1 hour, are compared with that of isolated flares (no flare in the region half a day before). Isolated flares appear to be formed of two components, a surging arch and a flaring arch, while a set of CCHF may be composed of consecutive elementary flares or of a series of complex ones. It is shown that the onset of eruptive flare phenomena is not the same for an isolated event and for a member of CCHF (excluding the first) as found in H-alpha and EUV observations, and probably in X-ray observations also. It is suggested that a CCHF set would become a single flare with episodic enhancement of brightness by taking account of the common H-alpha behavior of surging and flaring arches as well as the EUV emission.
    Schlagwort(e): SOLAR PHYSICS
    Materialart: (ISSN 0273-1177)
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  • 68
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    Microwave and hard X-ray observations of a solar flare with a time resolution better than 100 ms (1983)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: Simultaneous microwave and X-ray observations are presented for a solar flare detected on 1980 May 8 starting at 1937 UT. The X-ray observations were made with the Hard X-ray Burst Spectrometer on the Solar Maximum Mission and covered the energy range from 28-490 keV with a time resolution of 10 ms. The microwave observations were made with the 5 and 45 foot antennas at the Itapetinga Radio Obervatory at frequencies of 7 and 22 GHz, with time resolutions of 100 ms and 1 ms respectively. Detailed correlation analysis of the different time profiles of the event show that the major impulsive in the X-ray flux preceded the corresponding microwave peaks at 22 GHz by about 240 ms. For this particular burst the 22 GHz peaks preceded the 7 GHz by about 1.5s. Observed delays of the microwave peaks are too large for a simple electron beam model but they can be reconciled with the speeds of shock waves in a thermal model. Previously announced in STAR as N82-30215
    Schlagwort(e): SOLAR PHYSICS
    Materialart: Solar Physics (ISSN 0038-0938); 84; April 19
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  • 69
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    The isotopic composition of solar flare noble gases (1983)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: The relative elemental and isotopic abundances of noble gases provide insights into a number of topics related to the solar system. Neon is in many ways the most diagnostic of the noble gases. The diagnostic character is mainly related to the variation in the relative abundance of the two most abundant neon isotopes, Ne-20 and Ne-22. The available evidence suggests that trapped neon found in meteorites and in lunar samples consists of as many as five isotopically distinct components, including neon A, B, C, D, and E. Neon B has been shown to be due to solar wind neon which has been directly implanted into the material found in a meteorite. It appears that neon E is extrasolar in origin. There exist ambiguities regarding the origins of the remaining three components. The present investigation is concerned with a reexamination of the existing data in an effort to eliminate or at least clarify these ambiguities. It is found that neon C is apparently due to directly implanted, low-energy solar flare neon nuclei.
    Schlagwort(e): SOLAR PHYSICS
    Materialart: Astrophysical Journal; vol. 266
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  • 70
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    Unified Analysis for Antenna Pointing and Structural Errors. Part 1. Review (1983)
    In:  CASI
    Details
    Publikationsdatum: 2014-09-10
    Beschreibung: A necessary step in the design of a high accuracy microwave antenna system is to establish the signal error budget due to structural, pointing, and environmental parameters. A unified approach in performing error budget analysis as applicable to ground-based microwave antennas of different size and operating frequency is discussed. Major error sources contributing to the resultant deviation in antenna boresighting in pointing and tracking modes and the derivation of the governing equations are presented. Two computer programs (SAMCON and EBAP) were developed in-house, including the antenna servo-control program, as valuable tools in the error budget determination. A list of possible errors giving their relative contributions and levels is presented.
    Schlagwort(e): MECHANICAL ENGINEERING
    Materialart: The Telecommun. and Data Acquisition Rept.; p 40-59
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  • 71
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    Observations of the longitudinal magnetic field in the transition region and photosphere of a sunspot (1982)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: The Ultraviolet Spectrometer and Polarimeter on the Solar Maximum Mission spacraft has observed for the first time the longitudinal component of the magnetic field by means of the Zeeman effect in the transition region above a sunspot. The data presented here were obtained on three days in one sunspot, have spatial resolutions of 10 arcsec and 3 arcsec, and yield maximum field strengths greater than 1000 G above the umbrae in the spot. The method of analysis, including a line-width calibration feature used during some of the observations, is described in some detail in an appendix; the line width is required for the determination of the longitudinal magnetic field from the observed circular polarization. The transition region data for one day are compared with photospheric magnetograms from the Marshall Space Flight Center. Vertical gradients of the magnetic field are compared from the two sets of data; the maximum gradients of 0.41 to 0.62 G/km occur above the umbra and agree with or are smaller than values observed previously in the photosphere and low chromosphere.
    Schlagwort(e): SOLAR PHYSICS
    Materialart: Solar Physics; 81; Dec. 198
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  • 72
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    Stationarity of magnetohydrodynamic fluctuations in the solar wind (1982)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: (Previously announced in STAR as N83-11007)
    Schlagwort(e): SOLAR PHYSICS
    Materialart: Journal of Geophysical Research; 87; Dec. 1
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  • 73
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    A three-component model of the variability of the solar ultraviolet flux 145-200 nM (1982)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: The variability of the ultraviolet flux between 145 and 200 nm over both the eleven-year cycle and the 27-day solar rotation period is examined in terms of chromospheric activity, as determined from ground-based observations of the CaII K chromosphere. A three-component model of the solar UV flux is developed which includes the contributions to the full disk flux from both plage and active network emission. Solar cycle and solar rotation variations derived from the model are compared with the results of satellite and rocket experiments and with the two-component model of Cook et al (1980). Finally, possible ways of improving the model are discussed.
    Schlagwort(e): SOLAR PHYSICS
    Materialart: Journal of Geophysical Research; 87; Dec. 1
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  • 74
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    Active-region evolution and solar rotation variations in solar UV irradiance, total solar irradiance, and soft X rays (1982)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: Variations in the total solar irradiance, solar UV spectral irradiance, and solar soft X-ray emission caused by active region evolution and solar rotation are analyzed by using concurrent measurements from the NIMBUS 7 and GOES satellites. The observations are interpreted by using simple empirical models that relate ground-based observations of the size and location of sunspots and plages to the full-disk temporal variations. It is found that the major dips in the photospheric total solar irradiance S, which are evident in both satellite measurements and model predictions, are usually not accompanied by outstanding enhancements in the chromospheric and upper photospheric UV spectral irradiance or coronal X rays. The main cause of this difference between the variability of S and of the UV flux is that the total chromospheric plage enhancements are not outstanding at those times when the total sunspot are outstanding. X rays are even more variable because of a much wider CMD sensitivity.
    Schlagwort(e): SOLAR PHYSICS
    Materialart: Journal of Geophysical Research; 87; Dec. 1
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  • 75
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    Magnetic clouds - Voyager observations between 2 and 4 AU (1982)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: (Previously announced in STAR as N82-13593)
    Schlagwort(e): SOLAR PHYSICS
    Materialart: Solar Physics; 81; Nov. 198
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  • 76
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    Proposed Mg V, Fe XIV and forbidden Fe XVII line identifications in the EUV solar spectrum (1982)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Schlagwort(e): SOLAR PHYSICS
    Materialart: Solar Physics; 81; Nov. 198
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  • 77
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    Dynamics of the eruptive prominence of 6 May 1980 and its relationship to the coronal transient (1982)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: The active prominence of the 6 May 1980 has been observed between 5.23 and 10.22 UT with the Ultraviolet Spectrometer and Polarimeter (UVSP) on board the Solar Maximum Mission (SMM) satellite. Intensities of 1548 A line of CIV and dopplershifts have been derived. A motion of the magnetic tube maintaining the prominence material is noted. This motion is followed by a coronal transient observed with the Coronagraph and Polarimeter (C/P) between 11 and 13 UT. It is suggested that the event is related to a MHD wave induced by a flare occurring behind the solar disk, and a MHD modeling of the perturbation is proposed.
    Schlagwort(e): SOLAR PHYSICS
    Materialart: Astronomy and Astrophysics; 114; 1, Oc; Oct. 198
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  • 78
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    Welding Research (1982)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: Welding fabrication and welding processes were studied. The following research projects are reported: (1) welding fabrication; (2) residual stresses and distortion in structural weldments in high strength steels; (3) improvement of reliability of welding by in process sensing and control (development of smart welding machines for girth welding of pipes); (4) development of fully automated and integrated welding systems for marine applications; (5) advancement of welding technology; (6) research on metal working by high power laser (7) flux development; (8) heat and fluid flow; (9) mechanical properties developments.
    Schlagwort(e): MECHANICAL ENGINEERING
    Materialart: The Mater. Process. Res. Base of the Mater. Process Center; p 217-277
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  • 79
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    Adaptive materials processing (1982)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: New sensors for both arc welding and resistance spot welding processes were studied. For arc welding, the arc itself is used as the sensor. Minor changes in both composition and geometry of the plasma result in fluctuations in the arc voltage. While the process as currently employed is an off-line system, development of an on-line process controller would be possible once the optimum analysis technique is developed. It has been shown that for resistance spot welding, the dynamic resistance of the weld joint can be correlated to growth of the fusion zone. It is indicated that this technique is not as useful for projection welds as for spot welds.
    Schlagwort(e): MECHANICAL ENGINEERING
    Materialart: The Mater. Process. Res. Base of the Mater. Process. Center; p 155-158
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  • 80
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    The structure, stability and flaring of solar coronal loops (1982)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: A review is given of recent progress in the theory of the magnetohydrodynamic behavior of coronal loops, beginning with a brief characterization of thy observations. The equilibrium magnetic field is described, along with the consequences of the empirical requirement for short-term, or infinite-conductivity, stability which is shown to be dominated by the end-effect influence of thy quasi-rigid photosphere. A new loop-flare model is then developed, which takes account of the finite loop length. The primary resistive-sausage-mode instability exhibits the necessary threshold behavior, and produces a number of spatially and energetically distinct flare-release manifestations.
    Schlagwort(e): SOLAR PHYSICS
    Materialart: Societa Astronomica Italiana; vol. 53
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  • 81
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    Quadrupole distortions of the heliospheric current sheet in 1976 and 1977 (1982)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: Latitudinal variations in the position of the heliospheric current sheet were investigated using interplanetary measurements from Helios A, Helios B, IMP 8, and white light corona measurements in the period May 1976 to May 1977. The latitude of the heliospheric current sheet between 0.3 AU and I AU is consistent with that of the maximum brightness curve of white light polarization brightness at 1.75 solar radii within approximately + or - 7 deg. The combined data sets show that the four-sector magnetic sector pattern observed in the ecliptic plane for most of this epoch could be attributed to a warped current sheet whose shape near the sun resembles a saddle surface that is nearly symmetrical about the equatorial plane. The latitudinal extent of the current sheet is on the average 8 deg and the maximum extent is 15 deg (except on one rotation, when it is 20 deg). These results can be interpreted as a consequence of the solar magnetic field, the dominant components of the field being due to a dipole nearly aligned with the sun's spin axis and a quadrupole component whose strength is about 17 percent of the dipole.
    Schlagwort(e): SOLAR PHYSICS
    Materialart: Journal of Geophysical Research; 87; Dec. 1
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  • 82
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    The rotational spectrum of g-modes in the sun (1983)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: Observations and calculations are presented which strongly suggest that the unique sequence of rotation rates due to g-modes is active in the sun. It is found that all angular harmonics from 1 = 2-11 appear to be resolved, while higher harmonics up to at least 1 = 20 also seem to be active. The extreme narrowness of many of the spectral lines indicates that the g-modes are locked in sets of constant 1 by a local mechanism which excites the modes and possibly regulates the long-term precision of their rotation. These sets act as a system of resonant, or nearly resonant, clocks which impose a degree of periodicity upon solar activity and measure the mean solar interior rotation
    Schlagwort(e): SOLAR PHYSICS
    Materialart: Astrophysical Journal; vol. 264
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  • 83
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    Measurements of solar transition zone velocities and line broadening using the ultraviolet spectrometer and polarimeter on the Solar Maximum Mission (1982)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: The UVSP instrument on SMM is able to observe solar regions at two wavelengths in the same line with a band-pass of 0.3 A. Intensity and Doppler velocity maps are derived. It is shown that the numerical values are sensitive to the adopted Doppler width and the range of velocities is limited to within 30 km/sec. A method called Double Dopplergram Determination (DDD) is described for deriving both the Doppler width and the velocity (up to 80 km/sec), and the main sources of uncertainties are discussed. To illustrate the method, a set of C IV 1548 A observations is analyzed according to this procedure. The mean C IV Doppler width measured (0.15 A) is comparable to previous determinations. A relation is found between bright regions and down-flows. Large Doppler widths correspond to strong velocity gradients.
    Schlagwort(e): SOLAR PHYSICS
    Materialart: Astronomy and Astrophysics; 115; 2, No; Nov. 198
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  • 84
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    A dispersion law for solar oscillations (1982)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: The simple model of p-mode solar oscillations of Liebacher and Stein (1981), in which the acoustic vibrations are trapped in a resonant cavity taking the form of a spherical shell below the solar surface, is compared with Doppler shift observations of vertical velocities. The model is shown to predict a modified dispersion law in which the sound travel time across the cavity is a function of the ratio of the temporal frequency to the horizontal wavenumber, resulting in a single curve when the temporal frequency is plotted against the wavenumber. Frequencies derived from a two-dimensional power spectrum of velocity observations are found to conform to a modified version of the dispersion relation, and that only when the fundamental mode is excluded. Results thus suggest that all modes with the same frequency/wavenumber ratio are trapped in an identical cavity, or, more plausibly, that the difference in upper boundary conditions for different modes has minimal effect on the resulting frequencies.
    Schlagwort(e): SOLAR PHYSICS
    Materialart: Nature; 300; Nov. 18
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  • 85
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    Observation of chromospheric evaporation during the Solar Maximum Mission (1983)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: A study is presented of the upward motions of part of the soft X-ray emitting plasma using data for flares collected in 1980 by the Bent Crystal Spectrometer and the Hard X-ray Burst Spectrometer on the Solar Maximum Mission satellite. Results show that upward motions of the soft X-ray plasma are temporally associated with the build up of the thermal phase of flares and with the period of energy deposition as indicated by the hard X-ray emission. In addition, it is found that the hardness of the hard X-ray spectrum, the evaporation velocity, and the rate of increase of the gradual phase are correlated. It is also possible that the total electron energy deposited in the chromosphere, the peak emission measure of the evaporating plasma, and the peak emission measure of the thermal coronal plasma may also be correlated.
    Schlagwort(e): SOLAR PHYSICS
    Materialart: (ISSN 0038-0938)
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    Standort Signatur Erwartet Verfügbarkeit
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  • 86
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    Conductive flux in the chromosphere derived from line linear polarization observation (1983)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: It is shown that quantitative information on the mechanisms of energy transport which take place in solar flares can be obtained by measurement of impact line polarization. Linear polarization in two chromospheric lines (H-alpha and SI 1437 A) observed in the gradual phase of solar flares was investigated. The polarized electric vector is shown to be directed towards the center of the disk. The relationship between conductive heat flux and linear line polarization is determined using a function which represents the velocity distribution of electrons carrying heat flux. The relationship between linear polarization and heat flux is applied to the observed degree of polarization, which yields the conductive heat flux in the high chromosphere. It is determined that this conductive flux is of the order of magnitude of the total radiation loss in the chromosphere and below, which is also of the order of magnitude of the conductive flux in the transition zone.
    Schlagwort(e): SOLAR PHYSICS
    Materialart: (ISSN 0038-0938)
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  • 87
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    Radio blips and hard X-rays in solar flares (1983)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: The properties of short, narrow-band spikes occurring in groups at decimetric wavelengths have been extensively analyzed. The bursts, termed blips in the literature, have been found to appear in the impulsive phase of flares. They are associated with hard X-ray emission in 40 percent of all cases with simultaneous coverage. The correspondence between blips and X-ray spikes is generally not one-to-one, blips being more numerous than X-ray spikes. In some cases, however, close correlations between single events have been found. Blips have been discovered to drift in frequency and to decay in time similarly to type III bursts at lower frequency. They also resemble type III bursts in polarization. An analysis of starting frequencies, however, clearly shows that blips and type III bursts belong to different statistical populations. The narrow bandwidth of blips, the major qualitative difference with respect to type III bursts, suggests that blips are the signature of electron beams which either decay rapidly or have a locally enhanced emission due to the presence of some low-frequency wave. Blips have been shown to be an impulsive phase phenomenon occurring at densities of one to three billion per cu cm in the low corona.
    Schlagwort(e): SOLAR PHYSICS
    Materialart: Astrophysical Journal, Part 1 (ISSN 0004-637X); 271; Aug. 1
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  • 88
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    Flare buildup in X-rays, UV, microwaves and white light (1982)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: Coordinated observations using space and ground-based instruments were made of active region complex numbers 2522/2530, 24-30 June, 1980. The 10 largest flares from these regions were of importance M1-M6 in X-rays, and all were observed from satellites, except for one observed from a balloon. Several kinds of buildup signature have been found in the tens of minutes before these flares. Among these signatures are the following: (1) relative faintness in X-ray lines of the pre-flare pixels, (2) X-ray (5-15 keV) 'flashes' at points displaced by 1-2 arcmin from the flare site, (3) rising filaments seen in H-alpha and ultraviolet, (4) microwave intensification, polarization increase, and polarization flip, and (5) coronal disturbances above limb flares at or before the impulsive phase.
    Schlagwort(e): SOLAR PHYSICS
    Materialart: (ISSN 0273-1177)
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  • 89
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    Flare build-up study: Homologous flares group - Interim report (1982)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: When homologous flares are broadly defined as having footpoint structures in common, it is found that a majority of flares fall into homologous sets. Filament eruptions and mass ejection in members of an homologous flare set show that maintainance of the magnetic structure is not a necessary condition for homology.
    Schlagwort(e): SOLAR PHYSICS
    Materialart: (ISSN 0273-1177)
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  • 90
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    Particle acceleration by coronal and interplanetary shock waves (1982)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: Utilizing many years of observation from deep space and near-earth spacecraft a theoretical understanding has evolved on how ions and electrons are accelerated in interplanetary shock waves. This understanding is now being applied to solar flare-induced shock waves propagating through the solar atmosphere. Such solar flare phenomena as gamma-ray line and neutron emissions, interplanetary energetic electron and ion events, and Type II and moving Type IV radio bursts appear understandable in terms of particle acceleration in shock waves.
    Schlagwort(e): SOLAR PHYSICS
    Materialart: (ISSN 0273-1177)
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  • 91
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    Physical conditions in a quiescent prominence derived from UV spectra obtained with the UVSP instrument on the SMM (1983)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: A quiescent prominence observed above the north-west limb on November 20, 1980, is analyzed using data obtained with the UV spectrometer and polarimeter (UVSP) on the Solar Maximum Mission (SMM). The spectral data include the lines 1215 A of H1, 1401 A of OIV, 1402 A of SIIV, 1548 A of CIV, 1640 A of HeI, and 1655 A of CI. From an analysis of these lines and their emission patterns, the physical characteristics of the prominence plasma are deduced, and it is suggested that the prominence consisted of flux tubes at various temperatures. In the hotter parts of the plasma the number density reached values of about 3 x 10 to the 11th/cu cm.
    Schlagwort(e): SOLAR PHYSICS
    Materialart: Solar Physics (ISSN 0038-0938); 84; April 19
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  • 92
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    Vertical gradients of sunspot magnetic fields (1983)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: The results of a Solar Maximum Mission (SMM) guest investigation to determine the vertical gradients of sunspot magnetic fields for the first time from coordinated observations of photospheric and transition-region fields are described. Descriptions are given of both the photospheric vector field of a sunspot, derived from observations using the NASA Marshall Space Flight Center vector magnetograph, and of the line-of-sight component in the transition region, obtained from the SMM Ultraviolet Spectrometer and Polarimeter instrument. On the basis of these data, vertical gradients of the line-of-sight magnetic field component are calculated using three methods. It is found that the vertical gradient of Bz is lower than values from previous studies and that the transition-region field occurs at a height of approximately 4000-6000 km above the photosphere.
    Schlagwort(e): SOLAR PHYSICS
    Materialart: Solar Physics (ISSN 0038-0938); 84; April 19
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  • 93
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    Dynamics and spectroscopy of asymmetrically heated coronal loops (1983)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: Numerical models of steady flows along coronal magnetic flux tubes of varying cross sectional areas are investigated. The flows are induced by altering the spatial symmetry of the heating. In two cases the flux tube geometry is symmetric about the top of the loop, but the spatial dependence of the heating rate is changed from a symmetric deposition which supports a stationary equilibrium to a time-independent asymmetric deposition. In a third case the volumetric heating rate is uniform, but one half of the loop is larger in volume than the other. The resulting velocity structure varies significantly with changes in the flux tube geometry. Calculations of the ionization balance and line emission for a number of ionization stages of oxygen suggest that heating induced flows may be responsible for the redshifts seen in spectral lines formed in the network at transition region temperatures.
    Schlagwort(e): SOLAR PHYSICS
    Materialart: Astrophysical Journal; vol. 267
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  • 94
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    A magnetic cloud and a coronal mass ejection (1982)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: An interplanetary magnetic cloud observed by the Helios 1 spacecraft was found to be associated with a coronal mass ejection observed by the NRL Solwind coronagraph on the spacecraft P78-1. The magnetic cloud was observed on June 20, 1980, when Helios 1 was at 0.54 AU and nearly 90 deg west of the earth-sun line. This was associated with a large loop-like coronal mass ejection observed over the west limb on June 18, 1980, moving toward Helios 1. The speed of the front of the event at Helios 1 was (470 + or - 10) km/s, which is close to the mean transit speed (approximately 500 km/s). The magnetic cloud was similar to others described in the literature: The magnetic field strength was higher than average; the density was relatively low; the magnetic pressure greatly exceeded the ion thermal pressure; and the magnetic field direction changed through the cloud by rotating parallel to a plane which was highly inclined with respect to the ecliptic.
    Schlagwort(e): SOLAR PHYSICS
    Materialart: Geophysical Research Letters; 9; Dec. 198
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  • 95
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    Ferrographic and spectrometer oil analysis from a failed gas turbine engine (1983)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: An experimental gas turbine engine was destroyed as a result of the combustion of its titanium components. It was concluded that a severe surge may have caused interference between rotating and stationary compressor parts that either directly or indirectly ignited the titanium components. Several engine oil samples (before and after the failure) were analyzed with a Ferrograph, and with plasma, atomic absorption, and emission spectrometers to see if this information would aid in the engine failure diagnosis. The analyses indicated that a lubrication system failure was not a causative factor in the engine failure. Neither an abnormal wear mechanism nor a high level of wear debris was detected in the engine oil sample taken just prior to the test in which the failure occurred. However, low concentrations (0.2 to 0.5 ppm) of titanium were evident in this sample and samples taken earlier. After the failure, higher titanium concentrations (2 ppm) were detected in oil samples taken from different engine locations. Ferrographic analysis indicated that most of the titanium was contained in spherical metallic debris after the failure. The oil analyses eliminated a lubrication system bearing or shaft seal failure as the cause of the engine failure. Previously announced in STAR as N83-12433
    Schlagwort(e): MECHANICAL ENGINEERING
    Materialart: Wear (ISSN 0043-1648); 90; 239-249
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  • 96
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    Microwave signatures from a reconnecting plasma pinch, with application to loop flares (1983)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: A calculation is made of microwave signature of a cylindrical plasma pinch undergoing magnetic reconnection, a process which occurs in many astrophysical situations, such as solar flares. Depending on the viewing angle and the average energy of the accelerated electrons, the microwaves from this betatron-like source show various amounts of circular polarization. The degree of polarization is shown to be frequency dependent, and the sense of polarization is sometimes reversed. The power spectrum is predicted to have several interesting properties, which can be compared with high-resolution measurements.
    Schlagwort(e): SOLAR PHYSICS
    Materialart: Astrophysical Journal, Part 1 (ISSN 0004-637X); 275; 901-915
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  • 97
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    Effects of core perturbations on the structure of the sun (1983)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: The effects of perturbing the inner part of the solar core where the hydrogen abundance has been partially depleted by nuclear burning are investigated. Small regions are mixed within the core and the evolution of the resulting luminosity and radius perturbations is followed. The sensitivity of the solar luminosity and radius to mixing events of different sizes and at different locations in the core is determined and several relationships between the luminosity and radius perturbations are examined to see if the value of one of these perturbations can be inferred from a measurement of the other. It is found that any core perturbation which alters the hydrostatic structures will immediately affect the solar luminosity and radius. The behavior of these perturbations depends on the location of the mixing event within the core. Mixing events cannot produce the decrease in the solar radius without leading to a homogeneous evolution of the solar core and/or to a prohibitively large change in the solar luminosity.
    Schlagwort(e): SOLAR PHYSICS
    Materialart: Astrophysical Journal, Part 1 (ISSN 0004-637X); 273; 795-804
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  • 98
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    Si III line ratios in the sun (1983)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: New atomic data for Si III have been used to predict level populations and emission-line intensity ratios for electron densities and temperatures appropriate to the solar transition region. The electron impact collision rates used here are substantially larger than those previously published owing to delineation of the complex resonance structures in the low-energy collision strengths. This together with small changes in the spontaneous radiative rates produces significant changes in the calculated intensity ratios. Generally good agreement is found with observations obtained using the Naval Research Laboratory slit spectrograph aboard Skylab, electron densities from three Si III ratios and from other methods normally agreeing to 0.2 dex or better for a wide variety of solar features. For a fourth ratio, incorporating lines with a wide wavelength separation, the agreement is less satisfactory, possibly owing to uncertainties in the observational data.
    Schlagwort(e): SOLAR PHYSICS
    Materialart: Astrophysical Journal, Part 1 (ISSN 0004-637X); 274; 420-428
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  • 99
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    Lines of Fe XII sensitive to coronal electron density (1983)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: Lines of Fe XII sensitive to coronal electron density are discussed. The lines appear in solar spectra obtained by the Naval Research Laboratory (NRL) slit spectograph flown on Skylab. These lines are due to transitions between levels of the 3s 2 3p 3 configuration and fall at the wavelengths 1242.03 A, 1349.38 A, 2169.03 A, 2405.71 A, and 2565.99 A. It is shown that the line at 2169.03 A is severely blended by a line of Ni II at heights less than 12 arcsec outside the solar limb. Above 12 arcsec the lines at 2169.03 and 2405.71 A are apparently unblended and can be used to derive electron densities. An average coronal electron pressure of 6 x 10 to the 14th/cu cm K is obtained. However, the emitting path lengths of the Fe XII lines, deduced using the electron densities and absolute intensities, are unrealistically large. The reason for this difficulty is unclear.
    Schlagwort(e): SOLAR PHYSICS
    Materialart: Astrophysical Journal, Part 1 (ISSN 0004-637X); 273; 822-828
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  • 100
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    Metal shell technology (1983)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: Metallic shells are fabricated for a size range from several millimeters down to less than 500 microns in diameter. The technology, developed at JPL, is based on the hollow-jet instability for the large-shell formation, and in addition, on the Bernoulli's force for the microbubble generation. Various materials were processed into hollow spheres, such as AL1100, tin, lead, and a metallic glass-forming alloy, AuPbSb. They exhibited a range of contrasting solidification behaviors and surface characteristics. Some of their potential applications will be explored in this paper.
    Schlagwort(e): MECHANICAL ENGINEERING
    Materialart: SAMPE Journal (ISSN 0091-1062); 19; 7-11
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