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  • Data
  • Other Sources  (522)
  • SOLAR PHYSICS  (278)
  • CYBERNETICS  (244)
  • 1985-1989  (522)
  • 1960-1964
  • 1950-1954
  • 1987  (522)
  • 1
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    Dynamical modelling of coordinated multiple robot systems (1987)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Description: The state of the art in the modeling of the dynamics of coordinated multiple robot manipulators is summarized and various problems related to this subject are discussed. It is recognized that dynamics modeling is a component used in the design of controllers for multiple cooperating robots. As such, the discussion addresses some problems related to the control of multiple robots. The techniques used to date in the modeling of closed kinematic chains are summarized. Various efforts made to date for the control of coordinated multiple manipulators is summarized.
    Keywords: CYBERNETICS
    Type: Purdue Univ. and Univ. of Southern California, Report of Workshop on Coordinated Multiple Robot Manipulators: Planning, Control, and Applications; 14 p
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  • 2
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    Active region influences upon the solar constant (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The influence that active regions have upon the solar constant is discussed. Sunspots appear to lower the solar constant for the few days in which they are located near central meridian. This raises the possibility that an 11-year, solar-cycle-related depression in the solar constant may occur. Recent findings concerning the physics of active regions suggest that sunspots and faculae are largely surface features. Within that surface faculae reradiate, within a few weeks, the 'missing energy' associated with sunspots. This is consistent with the observations showing that the solar constant does not have an 11-year cycle-related depression that some authors predicted. However, there is a secular variation in the solar constant, whose explanation is not completely understood.
    Keywords: SOLAR PHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 92; 818-822
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  • 3
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    Raising the AIQ of the Space Station (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Expert systems and robotics technologies are to be significantly advanced during the Space Station program. Artificial intelligence systems (AI) on the Station will include 'scars', which will permit upgrading the AI capabilities as the Station evolves to autonomy. NASA-Ames is managing the development of the AI systems through a series of demonstrations, the first, controlling a single subsystem, to be performed in 1988. The capabilities being integrated into the first demonstration are described; however, machine learning and goal-driven natural language understanding will not reach a prototype stage until the mid-1990s. Steps which will be taken to endow the computer systems with the ability to move from heuristic reasoning to factual knowledge, i.e., learning from experience, are explored. It is noted that the development of Space Station expert systems depends on the development of experts in Station operations, which will not happen until the Station has been used extensively by crew members.
    Keywords: CYBERNETICS
    Type: Aerospace America (ISSN 0740-722X); 25; 16
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  • 4
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    Flare research with the NASA/MSFC vector magnetograph - Observed characteristics of sheared magnetic fields that produce flares (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The present MSFC Vector Magnetograph has sufficient spatial resolution (2.7 arcsec pixels) and sensitivity to the transverse field (the noise level is about 100 gauss) to map the transverse field in active regions accurately enough to reveal key aspects of the sheared magnetic fields commonly found at flare sites. From the measured shear angle along the polarity inversion line in sites that flared and in other shear sites that didn't flare, evidence is found that a sufficient condition for a flare to occur in 1000 gauss fields in and near sunspots is that both: (1) the maximum shear angle exceed 85 degrees; and (2) the extent of strong shear (shear angle of greater than 80 degrees) exceed 10,000 km.
    Keywords: SOLAR PHYSICS
    Type: Solar Physics (ISSN 0038-0938); 113; 1-2,; 347-352
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  • 5
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    Robustness of active modal damping of large flexible structures (1987)
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    Publication Date: 2011-08-19
    Description: The method of active modal damping (AMD) is reviewed, and the pinhole/occulter facility (P/OF) is presented as a design example. This system is a large space system composed of a flexible beam, a gimbal-pointing system, and an optical alignment system mounted in the Shuttle cargo bay and excited by typical Shuttle disturbances. The AMD system performance is compared with that of a series-compensated control system.
    Keywords: CYBERNETICS
    Type: International Journal of Control (ISSN 0020-7179); 46; 1009-101
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  • 6
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    Nonlocal thermal transport in solar flares (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A flaring solar atmosphere is modeled assuming classical thermal transport, locally limited thermal transport, and nonlocal thermal transport. The classical, local, and nonlocal expressions for the heat flux yield significantly different temperature, density, and velocity profiles throughout the rise phase of the flare. Evaporation of chromospheric material begins earlier in the nonlocal case than in the classical or local calculations, but reaches much lower upward velocities. Much higher coronal temperatures are achieved in the nonlocal calculations owing to the combined effects of delocalization and flux limiting. The peak velocity and momentum are roughly the same in all three cases. A more impulsive energy release influences the evolution of the nonlocal model more than the classical and locally limited cases.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 320; 904-912
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  • 7
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    Explorations of electric current system in solar active regions. I - Empirical inferences of the current flows (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Techniques to identify sources of electric current systems and their channels of flow in solar active regions are explored. Measured photospheric vector magnetic fields together with high-resolution white-light and H-alpha filtergrams provide the data base to derive the current systems in the photosphere and chromosphere. As an example, the techniques are then applied to infer current systems in AR 2372 in early April 1980.
    Keywords: SOLAR PHYSICS
    Type: Solar Physics (ISSN 0038-0938); 109; 2, 19; 307-320
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  • 8
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    Time-scale synthesis of a closed-loop discrete optimal control system (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Keywords: CYBERNETICS
    Type: Journal of Guidance, Control, and Dynamics (ISSN 0731-5090); 10; 417-421
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  • 9
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    The capacity of the Hopfield associative memory (1987)
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    Publication Date: 2011-08-19
    Description: Techniques from coding theory are applied to study rigorously the capacity of the Hopfield associative memory. Such a memory stores n-tuple of + or - 1s. The components change depending on a hard-limited version of linear functions of all other components. With symmetric connections between components, a stable state is ultimately reached. By building up the connection matrix as a sum-of-outer products of m fundamental memories, it may be possible to recover a certain one of the m memories by using an initial n-tuple probe vector less than a Hamming distance n/2 away from the fundamental memory. If m fundamental memories are chosen at random, the maximum asymptotic value of m in order that most of the m original memories are exactly recoverable is n/(2 log n). With the added restriction that every one of the m fundamental memories be recoverable exactly, m can be no more than n/(4 log n) asymptotically as n approaches infinity. Extensions are also considered, in particular to capacity under quantization of the outer-product connection matrix. This quantized memory-capacity problem is closely related to the capacity of the quantized Gaussian channel.
    Keywords: CYBERNETICS
    Type: IEEE Transactions on Information Theory (ISSN 0018-9448); IT-33; 461-482
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  • 10
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    Comparisons of interplanetary type III storm footpoints with solar features (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The trajectories of 38 type III storms in the interplanetary medium have been deduced from ISEE-3 radio observations and extrapolated back to the sun to determine the Carrington coordinates of their footpoints. The analysis assumes radial motion of the solar wind, and the trajectories are projected radially back toward the surface for the last few solar radii. To identify the storm sources, the footpoints were compared to a variety of solar features: to the large-scale neutral line at the base of the current sheet, to active regions, to the small-scale neutral lines and H-alpha filaments which trace out active regions, and to coronal holes. Most of the footpoints were found to lie near active regions, in agreement with metric storm locations. There is a weak correlation with H-alpha filaments, no apparent association with the current sheet, and an anticorrelation with coronal holes. There is a small excess of storms in the leading half of magnetic sectors.
    Keywords: SOLAR PHYSICS
    Type: Solar Physics (ISSN 0038-0938); 109; 1, 19
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  • 11
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    Multiperiodic irradiance changes caused by r-modes and g-modes (1987)
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    Publication Date: 2011-08-19
    Description: More than 20 real periodicities ranging from 20 days to 2 years modulate the solar irradiance data accumulated since November 1978 by Nimbus 7. Many are quite strong during the first three years (solar maximum) and weak after that. There is a high correspondence between periods in irradiance and 28 periods predicted from the rotation and beating of global solar oscillations (r-modes and g-modes). Angular states l = 1, 2, and 3 are detected as well as some unresolved r-mode power at higher l. The prominence of beat periods implies a nonlinear system whose effective nonlinear power was measured to be about 2. This analysis constitutes a detection of r-modes in the sun, and determines from them a mean sidereal rotation rate for the convective envelope of 459 + or - 4 nHz which converts to a period of 25.2 days (27.1d, synodic).
    Keywords: SOLAR PHYSICS
    Type: Solar Physics (ISSN 0038-0938); 109; 1, 19
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  • 12
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    Meridional transport of magnetic flux in the solar wind between 1 and 10 AU - A theoretical analysis (1987)
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    Publication Date: 2011-08-19
    Description: Observations suggesting that the mean solar wind azimuthal field strength B(theta) near the ecliptic plane falls off more rapidly with heliocentric distance than would be expected in a classic Parker expansion is reexamined from a theoretical perspective using a three-dimensional MHD nonlinear numerical model for steady, corotating flow. For realistic solar wind parameters, it is found that a purely axisymmetric expansion can produce sizable magnetic flux deficits only when there are substantial meridional gradients in mean flow conditions localized about the ecliptic plane near the sun. Calculations on three-dimensional cororating flows are presented which demonstrate that latitudinal transport of magnetic flux by stream interactions may be an important consideration in generating the deficits in mean B(theta).
    Keywords: SOLAR PHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 92; 7241-725
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  • 13
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    Diagnosis and sensor validation through knowledge of structure and function (1987)
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    Publication Date: 2011-08-19
    Description: The liquid oxygen expert system 'LES' is proposed as the first capable of diagnostic reasoning from sensor data, using model-based knowledge of structure and function to find the expected state of all system objects, including sensors. The approach is generally algorithmic rather than heuristic, and represents uncertainties as sets of possibilities. Functional relationships are inverted to determine hypothetical values for potentially faulty objects, and may include conditional functions not normally considered to have inverses.
    Keywords: CYBERNETICS
    Type: IEEE Transactions on Systems, Man, and Cybernetics (ISSN 0018-9472); SMC-17; 360-368
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  • 14
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    The thermal stability of coronal loops by nonlinear diffusion asymptotics (1987)
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    Publication Date: 2011-08-19
    Description: A nonlinear reaction-diffusion equation and some additional constraints are derived which describe the time-dependent behavior of the temperature structure of the plasma in coronal loops. The equation is analyzed using nonlinear diffusion asymptotics, in particular singular perturbation techniques, and the results are interpreted in the context of the physical problem of the thermal stability and temporal behavior of the plasma. The results are consistent with the possibility of cyclic thermal behavior of the plasma, as suggested by Kuin and Martens (1982).
    Keywords: SOLAR PHYSICS
    Type: Astronomy and Astrophysics (ISSN 0004-6361); 179; 1-2,
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  • 15
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    Use of voice recognition for control of a robotic welding workcell (1987)
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    Publication Date: 2011-08-19
    Description: This paper describes work underway to evaluate the effectiveness of voice recognition systems as an element in the control of a robotic welding workcell. Factors being considered for control include program editor access security, preoperation checklist requirements, welding process variable control, and robot manipulator motion overrides. In the latter two categories, manual vocal control is being compared against manual tactile control and fully automatic control in terms of speed of response, accuracy, stability, reliability, and safety.
    Keywords: CYBERNETICS
    Type: IEEE Control Systems Magazine (ISSN 0272-1708); 7; 16-18
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  • 16
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    Nonlinear radiative condensation in a sheared magnetic field (1987)
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    Publication Date: 2011-08-19
    Description: A well-resolved two-dimensional nonlinear numerical simulation of the radiative/thermal instability in a sheared magnetic field is described which leads to filament formation. The condensation is initiated by a linearly unstable mode and widens until it is slowed by thermal conduction parallel to B. During the nonlinear evolution, the minimum temperature falls from 10 to the 6th K to 10 to the 4th K and eventually reaches a state of local thermal equilibrium in about five e-folding times.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal, Part 2 - Letters to the Editor (ISSN 0004-637X); 317; L91-L94
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  • 17
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    Kalman filtering, smoothing, and recursive robot arm forward and inverse dynamics (1987)
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    Publication Date: 2011-08-19
    Description: The recursive difference equations of Kalman filtering and Bryson-Frazier fixed time-interval smoothing, arising in the state estimation theory for linear state space systems, are used here to solve problems of serial manipulator inverse and forward dynamics. The configuration analyzed is that of a joint connected N-link serial manipulator attached to an immobile base. The equivalence between the filtering and smoothing techniques from state estimation theory and recursive robot dynamics methods is demonstrated. Several areas for future research are suggested.
    Keywords: CYBERNETICS
    Type: IEEE Journal of Robotics and Automation (ISSN 0882-4967); RA-3; 624-639
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  • 18
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    Nuclear processes and accelerated particles in solar flares (1987)
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    Publication Date: 2011-08-19
    Description: Nuclear processes and particle acceleration in solar flares are reviewed. The theory of gamma-ray and neutron production is discussed and results of calculations are compared to gamma-ray, neutron, and charged-particle observations from solar flares. The implications of these comparisons on particle energy spectra, total numbers, anisotropies, electron-to-proton ratios, as well as on acceleration mechanisms and the interaction site, are presented. The information on elemental and isotopic abundances derived from gamma-ray observations is compared to abundances obtained from escaping accelerated particles and other sources.
    Keywords: SOLAR PHYSICS
    Type: Space Science Reviews (ISSN 0038-6308); 45; 3-4,
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  • 19
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    Design of feedforward controllers for multivariable plants (1987)
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    Publication Date: 2011-08-19
    Description: Simple methods for the design of feedforward controllers to achieve steady-state disturbance rejection and command tracking in stable multivariable plants are developed in this paper. The controllers are represented by simple and low-order transfer functions and are not based on reconstruction of the states of the commands and disturbances. For unstable plants, it is shown that the present method can be applied directly when an additional feedback controller is employed to stabilize the plant. The feedback and feedforward controllers do not affect each other and can be designed independently based on the open-loop plant to achieve stability, disturbance rejection and command tracking, respectivley. Numerical examples are given for illustration.
    Keywords: CYBERNETICS
    Type: International Journal of Control (ISSN 0020-7179); 46; 1633-165
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  • 20
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    On the prospect of using butterfly diagrams to predict cycle minimum (1987)
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    Publication Date: 2011-08-19
    Description: Features enabling the prediction of the beginning and the length of a solar cycle, in addition to the turning points in the period-growth dichotomy, have been identified based on butterfly diagrams for the period from 1874 to the present. The present results indicate that cycle 21 will be a long-period cycle ending after July 1987. On the assumption that April 1985 was the first occurrence of high latitude new cycle (cycle 22) spots during the decline of cycle 21 (the old cycle), it is suggested that the last occurrence of high latitude old cycle spots was September 1983 and that the minimum for cycle 22 will be about 1986.7 + or - 1.1 yr.
    Keywords: SOLAR PHYSICS
    Type: Solar Physics (ISSN 0038-0938); 111; 2, 19; 255-265
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  • 21
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    10.7-cm solar radio flux and the magnetic complexity of active regions (1987)
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    Publication Date: 2011-08-19
    Description: During sunspot cycles 20 and 21, the maximum in smoothed 10.7-cm solar radio flux occurred about 1.5 yr after the maximum smoothed sunspot number, whereas during cycles 18 and 19 no lag was observed. Thus, although 10.7-cm radio flux and Zurich sunspot number are highly correlated, they are not interchangeable, especially near solar maximum. The 10.7-cm flux more closely follows the number of sunspots visible on the solar disk, while the Zurich sunspot number more closely follows the number of sunspot groups. The number of sunspots in an active region is one measure of the complexity of the magnetic structure of the region, and the coincidence in the maxima of radio flux and number of sunspots apparently reflects higher radio emission from active regions of greater magnetic complexity. The presence of a lag between sunspot-number maximum and radio-flux maximum in some cycles but not in others argues that some aspect of the average magnetic complexity near solar maximum must vary from cycle to cycle. A speculative possibility is that the radio-flux lag discriminates between long-period and short-period cycles, being another indicator that the solar cycle switches between long-period and short-period modes.
    Keywords: SOLAR PHYSICS
    Type: Solar Physics (ISSN 0038-0938); 111; 2, 19; 279-285
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  • 22
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    On the proposed associations of solar neutrino flux with solar particles, cosmic rays, and the solar activity cycle (1987)
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    Publication Date: 2011-08-19
    Keywords: SOLAR PHYSICS
    Type: Solar Physics (ISSN 0038-0938); 112; 1, 19; 1-15
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  • 23
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    Microwave emission above steady and moving sunspots (1987)
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    Publication Date: 2011-08-19
    Description: Two-dimensional maps of radio brightness temperature and polarization, computed assuming thermal emission with free-free and gyroresonance absorption, are compared with observations of active region 2502, performed at Westerbork at lambda = 6.16 cm during a period of 3 days in June 1980. The computation is done assuming a homogeneous model in the whole field of view and a force-free extrapolation of the photospheric magnetic field observed at MSFC with a resolution of 2.34 arcsec. The mean results are the following: (1) a very good agreement is found above the large leading sunspot of the group, assuming a potential extrapolation of the magnetic field and a constant conductive flux in the transition region ranging from .2 x 10 to the 6th to 10 to the 7th erg/sq cm 5; (2) a strong radio source, associated with a new-born moving sunspot, cannot be ascribed to thermal emission. It is suggested that this source may be due to synchrotron radiation by mildly relativistic electrons accelerated by resistive instabilities occurring in the evolving magnetic configuration. An order-of-magnitude computation of the expected number of accelerated particles seems to confirm this hypothesis.
    Keywords: SOLAR PHYSICS
    Type: Solar Physics (ISSN 0038-0938); 112; 1, 19
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  • 24
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    Radio range measurements of coronal electron densities at 13 and 3.6 centimeter wavelengths during the 1985 solar conjunction of Voyager 2 (1987)
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    Publication Date: 2011-08-19
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal, Part 2 - Letters to the Editor (ISSN 0004-637X); 323; L141-L14
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  • 25
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    Transient ionization and solar flare X-ray spectra (1987)
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    Publication Date: 2011-08-19
    Description: In this paper the effects of a transiently ionizing solar flare plasma on the X-ray spectrum of iron between 1.85 and 1.92 A are considered. The atomic physics of the nonequilibrium spectrum is discussed, and reasons for differences in appearance from ionization equilibrium spectra are explained. The effect of spectral resolution on the ability to detect transient ionization in the iron X-ray spectrum is illustrated by synthetic spectra. A synthetic transiently ionizing spectrum is applied to the interpretation of spectra obtained from the SOX 1 spectrometer on the Japanese Hinotori spacecraft. Some indications of transient ionization are found, although counting statistics negate a strong conclusion. A hypothetical spectrometer with about one order of magnitude more sensitivity than the SOX 1 Hinotori or the bent crystal spectrometer flown on the Solar Maximum Mission (SMM) is also considered. The ranges of plasma parameters such as plasma emission measure and density that are necessary for transient ionization to be detected by such an instrument are discussed.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 323; 799-809
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  • 26
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    Electronic hardware implementations of neutral networks (1987)
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    Publication Date: 2011-08-19
    Description: This paper examines some of the present work on the development of electronic neural network hardware. In particular, the investigations currently under way at JPL on neural network hardware implementations based on custom VLSI technology, novel thin film materials, and an analog-digital hybrid architecture are reviewed. The availability of such hardware will greatly benefit and enhance the present intense research effort on the potential computational capabilities of highly parallel systems based on neural network models.
    Keywords: CYBERNETICS
    Type: Applied Optics (ISSN 0003-6935); 26; 5085-509
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  • 27
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    Optoelectronic analogs of self-programming neural nets - Architecture and methodologies for implementing fast stochastic learning by simulated annealing (1987)
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    Publication Date: 2011-08-19
    Description: Self-organization and learning is a distinctive feature of neural nets and processors that sets them apart from conventional approaches to signal processing. It leads to self-programmability which alleviates the problem of programming complexity in artificial neural nets. In this paper architectures for partitioning an optoelectronic analog of a neural net into distinct layers with prescribed interconnectivity pattern to enable stochastic learning by simulated annealing in the context of a Boltzmann machine are presented. Stochastic learning is of interest because of its relevance to the role of noise in biological neural nets. Practical considerations and methodologies for appreciably accelerating stochastic learning in such a multilayered net are described. These include the use of parallel optical computing of the global energy of the net, the use of fast nonvolatile programmable spatial light modulators to realize fast plasticity, optical generation of random number arrays, and an adaptive noisy thresholding scheme that also makes stochastic learning more biologically plausible. The findings reported predict optoelectronic chips that can be used in the realization of optical learning machines.
    Keywords: CYBERNETICS
    Type: Applied Optics (ISSN 0003-6935); 26; 5093-510
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  • 28
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    Microflares in the solar magnetic network (1987)
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    Publication Date: 2011-08-19
    Description: Localized brightenings are found throughout the magnetic network in quiet sun image sequences obtained in the C IV 1548 A line by the SMM satellite's UV spectrometer and polarimeter. Some bright sites are short-lived, while others persist. Plots of the intensity fluctuations show that the enhancements at both short- and long-lived sites are the result of localized impulsive heating events that occur intermittently at the short-lived sites and in more rapid succession at the long-lived ones. The number of these events and their visibility in the wings of the C IV line are consistent with their identification as the explosive events seen in UV spectra.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 323; 380-390
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  • 29
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    The detection of global convection on the sun by an analysis of line shift data of the John M. Wilcox Solar Observatory at Stanford University (1987)
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    Publication Date: 2011-08-19
    Description: An analysis of the absorption line shift data of the John M. Wilcox Solar Observatory at Stanford University has yielded signatures of the existence of global convection on the sun. These include persistent periodic time variations in the east-west component of the velocity fields defined by fitting a slope to the line shift data in a certain longitude window at a specified latitude and longitude by the least squares method. The amplitude of the velocity fields estimated from these variations is of the order of 100 m/s. The results of the analysis also suggest that several modes of global convection coexist in the solar convection zone. Details of the analysis are given.
    Keywords: SOLAR PHYSICS
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  • 30
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    Order reduction in linear state estimation under performance constraints (1987)
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    Publication Date: 2011-08-19
    Description: The design and analysis of minimal-order state estimators for possibly time-varying linear systems, under constraints on the maximal allowable mean-square error, are considered. A global lower bound on the optimal error is derived, along with a lower bound on the minimal estimator order, needed for meeting the performance constraint. The ideal reduced-order estimator which satisfies the lower bound is derived, along with conditions for its realizability. When the ideal estimator is not realizable, its structure forms a suboptimal estimator, which maintains, in some sense, a local optimality property and is called the pseudoideal estimator. The mean-square error of the pseudoideal estimator defines upper bounds on the optimal error and on the estimator order needed for meeting the performance constraint. The lower and the upper bounds on the order define a reduced search set for the design problem. When the distance between the ideal and the pseudoideal estimators is sufficiently small in a certain numerical sense, the pseudoideal estimator may be considered optimal for practical purposes.
    Keywords: CYBERNETICS
    Type: IEEE Transactions on Automatic Control (ISSN 0018-9286); AC-32; 983-989
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    Hard X-ray and radio emission at the onset of great solar flares (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A study of the onset phase of ten great hard X-ray bursts is presented. It is shown from hard X-ray and radio observations in different wavelength ranges that the energization of the electrons proceeds on a global time-scale for some tens of seconds. In nine of the bursts, two phases of emission can be distinguished during the onset phase: the preflash phase (during which emission up to an energy limit ranging from some tens of keV to 200 keV is observed) followed ten to some tens of seconds later by the flash phase (where the count rate in all detector channels rises simultaneously to within some seconds). For two of the events, strong gamma-ray line emission is observed and is shown to start close to the onset of the flash phase.
    Keywords: SOLAR PHYSICS
    Type: Solar Physics (ISSN 0038-0938); 111; 1, 19
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    Varying self-inductance and energy storage in a sheared force-free arcade (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: An electric circuit analogy is used to model the build-up and storage of magnetic energy in the coronal loops known to exist in the atmosphere of the sun. The present parameterization of magnetic energy storage in an electric circuit analog uses a bulk current I flowing in the circuit and a self-inductance L. Because the self-inductance is determined by the geometry of the magnetic configuration any change in its dimensions will change L. If L is increased, the amount of magnetic energy stored and the rate at which magnetic energy is stored are both increased. One way of increasing L is to shear the magnetic field lines and increase their effective geometrical length. Using the force-free field approximation for a magnetic arcade whose field lines are sheared by photospheric motions, it is demonstrated that the increase of magnetic energy is initially due to the increase of the current intensity I and later mainly due to the increase of the self-inductance.
    Keywords: SOLAR PHYSICS
    Type: Astronomy and Astrophysics (ISSN 0004-6361); 180; 1-2,; 218-222
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    Simplified solution for a class of fading memory filters (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A fading memory filter is a least squares estimator (LSE) that applies an exponentially decaying weight to past measurements. When compared with a standard Kalman filter, its key advantages are asymptotic stability and reduced sensitivity to modeling errors. This paper derives a simple solution for a class of fading memory filters, resulting in a reduction in computational complexity. Steady state filter solutions are obtained for second- and third-order filters used in a global positioning system (GPS) receiver for high dynamic vehicles.
    Keywords: CYBERNETICS
    Type: IEEE Transactions on Aerospace and Electronic Systems (ISSN 0018-9251); AES-23; 355-360
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    Spherical harmonic analysis of steady photospheric flows (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A technique is presented in which full disk Doppler velocity measurements are analyzed using spherical harmonic functions to determine the characteristics of the spectrum of spherical harmonic modes and the nature of steady photospheric flows. Synthetic data are constructed in order to test the technique. In spite of the mode mixing due to the lack of information about the motions on the backside of the sun, solar rotation and differential rotation can be accurately measured and monitored for secular changes, and meridional circulations with small amplitudes can be measured. Furthermore, limb shift measurements can be accurately obtained, and supergranules can be fully resolved and separated from giant cells by their spatial characteristics.
    Keywords: SOLAR PHYSICS
    Type: Solar Physics (ISSN 0038-0938); 108; 1, 19
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    Robustness of extended-Kalman-type observers (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Robustness properties of extended-Kalman-type observers are investigated for linear plants when actuators and sensors have non-linearities or linear dynamics. Sufficient conditions for the stability of the estimation error are obtained for time-varying extended Kalman filters (EKF) for time-varying plants, and for constant-gain, exponentially weighted EKF for time-invariant plants. When the non-linearities are known only within bands of uncertainty, it is proved that the observer is non-divergent.
    Keywords: CYBERNETICS
    Type: International Journal of Control (ISSN 0020-7179); 45; 1857-186
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    Heating of the solar corona by the resonant absorption of Alfven waves (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: An improved method for calculating the resonance absorption heating rate is discussed and the results are compared with observations in the solar corona. To accomplish this, the wave equation for a dissipative, compressible plasma is derived from the linearized magnetohydrodynamic equations for a plasma with transverse Alfven speed gradients. For parameters representative of the solar corona, it is found that a two-scale description of the wave motion is appropriate. The large-scale motion, which can be approximated as nearly ideal, has a scale which is on the order of the width of the loop. The small-scale wave, however, has a transverse scale much smaller than the width of the loop, with a width of about 0.3-250 km, and is highly dissipative. These two wave motions are coupled in a narrow resonance region in the loop where the global wave frequency equals the local Alfven wave frequency. Formally, this coupling comes about from using the method of matched asymptotic expansions to match the inner and outer (small and large scale) solutions. The resultant heating rate can be calculated from either of these solutions. A formula derived using the outer (ideal) solution is presented, and shown to be consistent with observations of heating and line broadening in the solar corona.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 317; 514-521
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    On the apparent velocity of integrated sunlight. I - 1983-1985 (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Frequency measurements for the Delta V = 2 transitions of CO in the integrated light spectrum of the sun are presented. The nature and magnitude of systematic errors which typically arise in absolute velocity measurements of integrated sunlight are explored in some detail, and measurements believed accurate at the level of about 5 m/s or less are presented. It is found that the integrated light velocity varies by about 3 m/s or less over a one-day period. Over the long term, the data indicate an increasing blue-shift in these weak infrared lines amounting to 30 m/s from 1983 to 1985. The sense of the drift is consistent with a lessening in the magnetic inhibition of granular convection at solar minimum. Such an effect has implications for the spectroscopic detectability of planetary-mass companions to solar-type stars.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 316; 771-787
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    Changes in measured vector magnetic fields when transformed into heliographic coordinates (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The changes that occur in measured magnetic fields when they are transformed into a heliographic coordinate system are investigated. To carry out this investigation, measurements of the vector magnetic field of an active region that was observed at 1/3 the solar radius from disk center are taken, and the observed field is transformed into heliographic coordinates. Differences in the calculated potential field that occur when the heliographic normal component of the field is used as the boundary condition rather than the observed line-of-sight component are also examined. The results of this analysis show: (1) that the observed fields of sunspots more closely resemble the generally accepted picture of the distribution of umbral fields if they are displayed in heliographic coordinates; (2) that the differences in the potential calculations are less than 200 G in field strength and 20 deg in field azimuth outside sunspots; and (3) that differences in the two potential calculations in the sunspot areas are no more than 400 G in field strength but range from 60 to 80 deg in field azimuth in localized umbral areas.
    Keywords: SOLAR PHYSICS
    Type: Solar Physics (ISSN 0038-0938); 107; 2, 19; 239-246
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    Nonlinear evolution of radiation-driven thermally unstable fluids (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The nonlinear evolution of a radiation-driven thermally unstable planar fluid is simulated numerically using a semiimplicit finite-difference algorithm. When the equilibrium state of the fluid is perturbed by random initial excitation of the velocity field, dense, cool, two-dimensional structures are found to form in a rarer, warmer surrounding medium. The nonlinear phase of evolution is characterized by the turbulent contraction of the condensed region, accompanied by a significant increase in the amount of energy radiated. It is found that, if the random velocity perturbation has a sufficiently large amplitude, the fluid will not form condensed structures. Finally, the relationship of these results to observations of the solar chromosphere, transition region, and corona is discussed.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 315; 385-407
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    Solar irradiance change and special longitudes due to r-modes (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Sluggish global oscillations, having a periodicity of months and trapped in the sun's convection zone, modulate the amount of energy reaching earth and seem to impose some large-scale order on the distribution of solar surface features. These recently recognized oscillations (r-modes) increase the predictability of solar changes and may improve understanding of rotation and variability in other stars. Most of the 13 periodicities ranging from 13 to 85 days that are caused by r-modes can be detected in Nimbus 7 observations of solar irradiance during 3 years at solar maximum. These modes may also bear on the classical question of persistent longitudes of high solar activity.
    Keywords: SOLAR PHYSICS
    Type: Science (ISSN 0036-8075); 235; 1631-163
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    Nonpotential features observed in the magnetic field of an active region (1987)
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    Publication Date: 2011-08-19
    Description: A unique coordinated data set consisting of vector magnetograms, H-alpha photographs, and high-resolution ultraviolet images of a solar active region is used, together with mathematical models, to calculate potential and force-free magnetic field lines and to examine the nonpotential nature of the active region structure. It is found that the overall bipolar magnetic field of the active region had a net twist corresponding to net current of order 3 x 10 to the 12th A and average density of order 4 x 10 to the -4th A/sq m flowing antiparallel to the field. There were three regions of enhanced nonpotentiality in the interior of the active region; in one the field had a marked nonpotential twist or shear with height above the photosphere. The measured total nonpotential magnetic energy stored in the entire active region was of order 10 to the 32nd ergs, about 3 sigma above the noise level.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 314; 782-794
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    Solar wind stream structure at large heliocentric distances Pioneer observations (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Time profiles and histograms of plasma data from Pioneers 10 and 11 are examined for the period between 1975 and 1983. During this time, Pioneer 10 traveled between a heliocentric distance of 8.7 and 30.4 AU. The velocity structure of the solar wind at these heliocentric distances is found to have one of two distinct forms: approximately 70 percent of the time the solar wind has a nearly flat velocity profile. Occasionally, this flat velocity profile is accompanied by quasi-periodic variations in density and in thermal speed consistent with the concept that the 'corotating interaction regions' which are produced by the interaction of high- and low-speed streams at intermediate heliocentric distances are replaced by 'pressure regions' in the outer heliosphere. The remaining 30 percent of the time the solar wind is marked by large (50-200 km/s) long-term (30-120 days) shifts in the average solar wind velocity.
    Keywords: SOLAR PHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 92; 2231-224
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    Predictions for the total solar eclipse of 1988 (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A total eclipse of the sun will be widely visible from the East Indies on March 18, 1988. Detailed predictions for this event are presented which include tables of geographic coordinates for the northern limit, center line and southern limit of the path of totality, local circumstances for 40 cities within the total and partial eclipse paths, the lunar-limb profile, and maps depicting the path of totality. The author discusses the general characteristics of the eclipse, local circumstances from various points along the central path and the Saros-series history.
    Keywords: SOLAR PHYSICS
    Type: Royal Astronomical Society of Canada, Journal (ISSN 0035-872X); 81; 44-60
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    Proof of quasi-adaptivity for the m-measurement feedback class of stochastic control policies (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Bounds on expected performance are established which show that the m-measurement feedback (mM) policy for nonlinear stochastic control performs as well or better than the open-loop optimal control policy, and thus is quasi-adaptive in the sense of Witenhausen (1966). The chain of performance inequalities indicate a tendency for the mM policy performance to improve with increasing m. It is suggested that the present analytical method, based on the construction of artificial control sequences denoted as utility controls, can be used to establish performance bounds on other well-known policies, avoiding the extensive Monte Carlo simulations necessary in comparing stochastic control policies.
    Keywords: CYBERNETICS
    Type: IEEE Transactions on Automatic Control (ISSN 0018-9286); AC-32; 447-451
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    Using hybrid expert system approaches for engineering applications (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: In this paper, the use of hybrid expert system shells and hybrid (i.e., algorithmic and heuristic) approaches for solving engineering problems is reported. Aspects of various engineering problem domains are reviewed for a number of examples with specific applications made to recently developed prototype expert systems. Based on this prototyping experience, critical evaluations of and comparisons between commercially available tools, and some research tools, in the United States and Australia, and their underlying problem-solving paradigms are made. Characteristics of the implementation tool and the engineering domain are compared and practical software engineering issues are discussed with respect to hybrid tools and approaches. Finally, guidelines are offered with the hope that expert system development will be less time consuming, more effective, and more cost-effective than it has been in the past.
    Keywords: CYBERNETICS
    Type: Engineering with Computers (ISSN 0177-0667); 2; 2, 19; 95-110
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    Preflare energy build-up in a filament circuit (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The May 16, 1981 flare observed at Debrecen is studied by extending to a fully three-dimensional model the two-dimensional Van Tend and Kuperus (1978) scenario for preflare energy build-up. It is shown that there are 10 to the 33rd ergs of free energy available to explain the subsequent large two-ribbon flare. As a result of the three-dimensional character of the present model, this estimate is an order of magnitude larger than that made by Van Tend. It is confirmed that the global form of the preflare circuit is highly important in determining the amount of energy stored in the preflare configuration. The present model gives correct predictions for the independently observed photospheric flow velocity and current strength in filaments.
    Keywords: SOLAR PHYSICS
    Type: Solar Physics (ISSN 0038-0938); 107; 1, 19; 95-108
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    Large-scale fluctuations in the interplanetary medium (1987)
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    Publication Date: 2011-08-19
    Description: Power spectra of measurements of the magnetic field strength in the heliosphere obtained by Voyager 1 between 1 AU and 9 AU have the form of a power law f exp -a from periods of several hours to at least 6 days. The exponent was a = 2.0 + or - 0.05 for all of the spectra considered, which is the exponent for a series of steps and for Burgers' (1971) turbulence. Spectra of large-scale speed fluctuations also have the form f exp - b from a period of a few hours to periods greater than 13 days in the region from 1 AU to 8.9 AU. The exponent b is generally somewhat larger than b = 2, implying some 'persistence' of the speed fluctuations. The low-frequency cutoff (outer cutoff) of the power law increases from a period of 6.5 days at 1 AU to 26 days at (6.1-8.9) AU, which can be attributed to: (1) the coalescence of interaction regions and (2) a transfer of energy from the spectrum of large-scale speed fluctuations. The outer cutoff of the spectrum of speed fluctuations increases from a period of 13 days at 1 AU to 26 days between a few AU and 8.9 AU. Both the magnetic field strength fluctuations and the speed fluctuations have fractal behavior, suggesting that they are self affine rather than dominated by a few large discontinuities.
    Keywords: SOLAR PHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 92; 1261-126
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    Highlights of the study of energy release in flares (1987)
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    Publication Date: 2011-08-19
    Description: From February 26 to March 1, 1979, 32 solar flare investigators attended a workshop at Cambridge, MA to define objectives and devise a scientific program for the study of energy release in flares (SERF) during the coming solar maximum. Herein, some major results of the ensuing five-year effort to observe and understand the flare energy release process and its effects (energetic particle production, coronal and chromospheric heating, electromagnetic radiations, and mass motions and ejections) are reviewed. The central issue - what processes store and release the energy liberated in flares - remains unresolved except in the most general terms (e.g., it is generally agreed that the energy is stored in sheared or stressed magnetic fields and released by field annihilation during some MHD instability). Resolving that issue is still one of the most important goals in solar physics, but the advances during the SERF program have brought it closer.
    Keywords: SOLAR PHYSICS
    Type: Solar Physics (ISSN 0038-0938); 114; 2, 19
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    On the distribution of sunspot cycle periods (1987)
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    Publication Date: 2011-08-19
    Description: A comparison is made between the observed distribution of sunspot cycle periods and distributions based on uniform, normal, and bimodal distributions. The bimodal distribution, composed of short-period and long-period cycles, is found to best describe the observed distribution. Compared to the normal distribution for the most reliably determined cycles (cycles 8-20), the bimodal distribution has a residual (sum of squares of differences) that is about 86 percent smaller. Means for short-period and long-period cycles are estimated to be 122 + or - 4 months and 140 + or - 5 months, respectively.
    Keywords: SOLAR PHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 92; 10
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    Sunspot umbral oscillations in Mg II k (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Time series observations of the profile of the Mg II k line 2795.52 A have been obtained in five sunspots with the Ultraviolet Spectrometer and Polarimeter on the Solar Maximum Mission. The three sunspots with umbrae larger than the 3 x 3 arcsec pixel size show significant oscillations in integrated line intensity and line centroid, with frequencies in the range 5.29-7.55 mHz (periods of 132-190 s). The frequencies of significant peaks in average umbral power spectra agree well with the frequencies of the three lowest-frequency transmission peaks predicted by a model of resonant transmission of acoustic waves. If radiative delays are unimportant, and the line centroid can be interpreted straightforwardly as a Doppler shift, the measured velocity-intensity phase differences indicate the superposition of upward-propagating and downward-propagating waves in the umbral chromosphere; this is further evidence for the resonant transmission model. A single, quiet sun time series of k core profiles yields power spectra and a phase difference consistent with the existence of a chromospheric p-mode.
    Keywords: SOLAR PHYSICS
    Type: Solar Physics (ISSN 0038-0938); 108; 1, 19
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    Performance improvement of robots using a learning control scheme (1987)
    In:  CASI
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    Publication Date: 2013-08-31
    Description: Many applications of robots require that the same task be repeated a number of times. In such applications, the errors associated with one cycle are also repeated every cycle of the operation. An off-line learning control scheme is used here to modify the command function which would result in smaller errors in the next operation. The learning scheme is based on a knowledge of the errors and error rates associated with each cycle. Necessary conditions for the iterative scheme to converge to zero errors are derived analytically considering a second order servosystem model. Computer simulations show that the errors are reduced at a faster rate if the error rate is included in the iteration scheme. The results also indicate that the scheme may increase the magnitude of errors if the rate information is not included in the iteration scheme. Modification of the command input using a phase and gain adjustment is also proposed to reduce the errors with one attempt. The scheme is then applied to a computer model of a robot system similar to PUMA 560. Improved performance of the robot is shown by considering various cases of trajectory tracing. The scheme can be successfully used to improve the performance of actual robots within the limitations of the repeatability and noise characteristics of the robot.
    Keywords: CYBERNETICS
    Type: NASA, Goddard Space Flight Center, Proceedings of 1987 Goddard Conference on Space Applications of Artificial Intelligence (AI) and Robotics; 20 p
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    Kinetics of mineral condensation in the solar nebula (1987)
    In:  CASI
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    Publication Date: 2013-08-31
    Description: A natural extension of the type of gas-mineral-melt condensation experiments is to study the gas-mineral-melt reaction process by controlling the reaction times of appropriate gas compositions with silicate materials. In a condensing and vaporizing gas-solid system, important processes that could influence the composition of and speciation in the gas phase are the kinetics of vaporization of components from silicate crystals and melts. The high vacuum attainable in the space station would provide an environment for studying these processes at gas pressures much lower than those obtainable in experimental devices operated at terrestrial conditions in which the gas phase and mineral or melt would be allowed to come to exchange equilibrium. Further experiments would be performed at variable gas flow rates to simulate disequilibrium vapor fractionation. In this type of experiment it is desirable to analyze directly the species in the gas phase in equilibrium with the condensed silicate material. This analytical method would provide a direct determination of the species present in the gas phase. Currently, the notion of gas speciation is based on calculations from thermodynamic data. The proposed experiments require similar furnace designs and use similar experimental starting compositions, pressures, and temperatures as those described by Mysen.
    Keywords: SOLAR PHYSICS
    Type: NASA, Lyndon B. Johnson Space Center, Experiments in Planetary and Related Sciences and the Space Station; 2 p
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    A general architecture for intelligent training systems (1987)
    In:  CASI
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    Publication Date: 2013-08-31
    Description: A preliminary design of a general architecture for autonomous intelligent training systems was developed. The architecture integrates expert system technology with teaching/training methodologies to permit the production of systems suitable for use by NASA, other government agencies, industry, and academia in the training of personnel for the performance of complex, mission-critical tasks. The proposed architecture consists of five elements: a user interface, a domain expert, a training session manager, a trainee model, and a training scenario generator. The design of this architecture was guided and its efficacy tested through the development of a system for use by Mission Control Center Flight Dynamics Officers in training to perform Payload-Assist Module Deploys from the orbiter.
    Keywords: CYBERNETICS
    Type: NASA. Johnson Space Center, NASA(ASEE Summer Faculty Fellowship Program, 1987, Volume 2; 15 p
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    Large-scale horizontal flows from SOUP observations of solar granulation (1987)
    In:  CASI
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    Publication Date: 2013-08-31
    Description: Using high resolution time sequence photographs of solar granulation from the SOUP experiment on Spacelab 2, large scale horizontal flows were observed in the solar surface. The measurement method is based upon a local spatial cross correlation analysis. The horizontal motions have amplitudes in the range 300 to 1000 m/s. Radial outflow of granulation from a sunspot penumbra into surrounding photosphere is a striking new discovery. Both the supergranulation pattern and cellular structures having the scale of mesogranulation are seen. The vertical flows that are inferred by continuity of mass from these observed horizontal flows have larger upflow amplitudes in cell centers than downflow amplitudes at cell boundaries.
    Keywords: SOLAR PHYSICS
    Type: NASA-Goddard Space Flight Center, Theoretical Problems in High Resolution Solar Physics, 2; p 121-127
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    Loop interaction in the visible emission corona: Morphological details (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: Coronagraph observations of two post flare loop systems, recorded photographically in the emissions of Fe 14 (5303 A) and Fe 10 (6374 A), show occasional enhancements at the intersections of some loops. The brightness of such enhancements in the green line gradually increases to a maximum value several times greater than that of the legs of the loops and then declines with a typical lifetime approx. 30 to 60 min. In red line emission the loop systems are usually very faint, but show the same overall type of enhancement, with a lag in maximum brightness relative to that of the green line approx. 10 min. The electron density, derived from the cooling time, is approx. 10 to the 12th power/cu cm.
    Keywords: SOLAR PHYSICS
    Type: NASA-Goddard Space Flight Center, Theoretical Problems in High Resolution Solar Physics, 2; p 129-132
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    Solar transition region and coronal response to heating rate perturbations (1987)
    In:  CASI
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    Publication Date: 2013-08-31
    Description: The solar transition region is in a dynamic state characterized by impulsively upflowing plasma and continually downflowing plasma. Using numerical simulations, the conjecture that the areas of downflowing plasma are simply the base regions of coronal loops in which the heating rate is gradually decreasing and the areas of upflowing plasma are the base regions of coronal loops in which the heating rate is gradually increasing is examined. The calculations suggest that gradually reducing or increasing the heating in a magnetic flux tube will not result in plasma motions that are similar to those that are observed at high spatial resolution in the UV.
    Keywords: SOLAR PHYSICS
    Type: NASA-Goddard Space Flight Center, Theoretical Problems in High Resolution Solar Physics, 2; p 117-119
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    Pressure structure of solar coronal loops (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: The steady state pressure structure of a coronal loop is discussed in terms of the MHD global invariants of an incompressible plasma. The steady state is represented by the superposition of two Chandrasekhar-Kendall functions corresponding to (n=m=0) and (n=m=1) modes. The relative contribution of the two modes (epsilon) is found to depend on the surface pressure of the coronal loop which is also the pressure of the external medium. The mixed mode state does not exist for high values of the external pressure because epsilon becomes complex.
    Keywords: SOLAR PHYSICS
    Type: NASA-Goddard Space Flight Center, Theoretical Problems in High Resolution Solar Physics, 2; p 107-111
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    A numerical study of the thermal stability of solar loops (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: An important property of all loops is their thermal stability. If low lying hot loops were thermally unstable, for example, a great majority of the low loops on the Sun might be expected to be cool. How small perturbations evolve in low lying, linearly unstable hot loops was determined and how high lying, linearly stable hot loops respond to large amplitude disturbances such as might be expected on the Sun were examined. Only general descriptions and results are given.
    Keywords: SOLAR PHYSICS
    Type: NASA-Goddard Space Flight Center, Theoretical Problems in High Resolution Solar Physics, 2; p 113-116
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  • 59
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    Theoretical modelling of the fine structures in sunspots (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: Until a decade ago most solar physicists thought of a sunspot as the upper end of a giant flux tube floating vertically. The existence of umbral dots and penumbral grains has been known for several decades. On the basis of available observations, they seem to be regions of photospheric intensity with upflowing gas motion and magnetic fields much weaker than in the surrounding sunspot surface. It has also been suggested that the differences in the appearances of umbral dots and granular cells are caused by the highly nonlinear nature of the convection problem in the presense of strong magnetic fields. The main ideas are presented here without any equations. It can be shown that a pocket of field free gas surrounded by a vertical magnetic field in the presence of gravity takes up the shape of a tapering column ending at a vertex at the top. Some convection is expected to take place in the trapped field free gas, whereas the magnetic field around it makes those regions stable against convection. Eventually the apex of the tapering column reaches the photospheric surface where the bulging of the magnetic field makes the field no longer able to close on the field free gas and trap it underneath.
    Keywords: SOLAR PHYSICS
    Type: NASA-Goddard Space Flight Center, Theoretical Problems in High Resolution Solar Physics, 2; p 105-106
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  • 60
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    High-resolution continuum observations of the Sun (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: The aim of the PFI or photometric filtergraph instrument is to observe the Sun in the continuum with as high resolution as possible and utilizing the widest range of wavelengths. Because of financial and political problems the CCD was eliminated so that the highest photometric accuracy is only obtainable by comparison with the CFS images. Presently there is a limitation to wavelengths above 2200 A due to the lack of sensitivity of untreated film below 2200 A. Therefore the experiment at present consists of a film camera with 1000 feet of film and 12 filters. The PFI experiments are outlined using only two cameras. Some further problems of the experiment are addressed.
    Keywords: SOLAR PHYSICS
    Type: NASA-Goddard Space Flight Center, Theoretical Problems in High Resolution Solar Physics, 2; p 79-88
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  • 61
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    What's needed in the UV and EUV (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: High spectral and spatial resolution UV and EUV spectroscopy is discussed with emphasis on the spectroscopic observations that are required in order to increase the understanding of the physics of the lower transition region. The properties of the lower transition region are reviewed, and the available lower transition region plasma diagnostics are reviewed for the wavelength range between about 1150 and 2000 A. One important conclusion is that comprehensive spectroscopic coverage over a rather broad temperature range is necessary in order to observe satisfactorily small transition region structures. This is illustrated by two examples from the recent NRL Spacelab 2 HRTS experiment.
    Keywords: SOLAR PHYSICS
    Type: NASA-Goddard Space Flight Center, Theoretical Problems in High Resolution Solar Physics, 2; p 37-54
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  • 62
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    Magnetic field morphology in the upper layers (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: Some basic properties of emerged magnetic flux concentrations are examined with emphasis on the interplay between the magnetic and thermodynamic structure in the region between the photosphere and the transition zone. The discussion is limited to the gross behavior of those phenomena that may be reasonably regarded as quasi-static, such as the longer-lived sunspots, pores, and some smaller magnetic flux tubes. Substructure and dynamic phenomena are not considered.
    Keywords: SOLAR PHYSICS
    Type: NASA-Goddard Space Flight Center, Theoretical Problems in High Resolution Solar Physics, 2; p 1-13
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  • 63
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    An account of a flare related shock event recorded by the energetic particle detector EPONA of the Giotto spacecraft during September 1985 (STIP interval 18) (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: The Energetic Particle Detector EPONA flown on the Giotto Mission to Halley's Comet was designed to measure electrons, protons, and heavier ions (E greater that 20 keV) in the Comet Halley environment and during the Cruise Phase of the mission (EPONA switch on: 22 August 1985 - Halley encounter: 13 March 1986). In September 1985 (STIP Interval XVIII) a well defined shock event was recorded at EPONA in association with a sequence of solar flares and a preliminary account of this event is presented.
    Keywords: SOLAR PHYSICS
    Type: Alabama Univ., Huntsville. STIP Symposium on Physical Interpretation of Solar(Interplanetary and Cometary Intervals; p 56
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  • 64
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    Solar prediction and intelligent machines (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: The solar prediction program is aimed at reducing or eliminating the need to throughly understand the process previously developed and to still be able to produce a prediction. Substantial progress was made in identifying the procedures to be coded as well as testing some of the presently coded work. Another project involves work on developing ideas and software that should result in a machine capable of learning as well as carrying on an intelligent conversation over a wide range of topics. The underlying idea is to use primitive ideas and construct higher order ideas from these, which can then be easily related one to another.
    Keywords: SOLAR PHYSICS
    Type: NASA. Lyndon B.; NASA. Lyndon B. John
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  • 65
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    The temperature of solar flares determined from X-ray spectral line ratios (1987)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: The effect on derived solar flare plasma temperatures of (1) a power-law distribution of emission measure as a function of temperature, (2) a high-temperature isothermal source coupled to a low-temperature power-law distribution of emission measure, and (3) two isothermal sources is calculated for line ratios involving the ions S XV, Ca XIX, Ca XX, Fe XXV, Ni XXVII, and Fe XXVI. It is shown that if the Fe XXV temperature is less than about 25 million K, as is true for the majority of flares, then about 75 percent or more of the emission measure is produced by plasma at temperatures equal to or less than the Fe XXV temperature plus about 3 million K. If the Fe XXV temperature is 20 million K or higher, this percentage can be larger. This result is obtained even if a superhot component exists that extends up to several hundred million degrees. Temperatures determined from Fe XXVI demonstrate the presence of a superhot component.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 313; 883-892
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  • 66
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    Ultraviolet Al III emission lines and the physics of the solar transition region (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Two lines of the solar UV spectrum were identified as due to 3p-3d Al III transitions near 1612 A; the ratios of these lines to the 3s-3p Al III doublet near 1855 A were found to be very sensitive to temperature. Thus, the temperatures of formation of the Al III lines could be determined by using one of the line ratios in two quiet sun regions, a coronal hole, and an active region. The results were found to be consistent with expectations based on the assumption of ionization equilibrium for Al III. It is suggested that S III lines near 1350 A and 1200 A may also serve as a temperature diagnostic.
    Keywords: SOLAR PHYSICS
    Type: Astrophysical Journal, Part 2 - Letters to the Editor (ISSN 0004-637X); 315; L67-L70
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  • 67
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    Viscous damping of Alfven normal modes in non-uniform plasmas (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The Alfven normal mode in a nonuniform, viscous plasma is investigated. Because the ideal hydromagnetic equation is singular in a nonuniform magnetic field, viscosity is included in order to regularize the equation, analogous to the removal of the singular point by resistivity (Mok and Einaudi, 1985). The eigenvalue equation is then solved numerically for a particular magnetic configuration. The real part of the frequency of this viscous normal mode is found to be similar to the one in the resistive case, while the damping is shown to be comparable, and sometimes to exceed, the resistive effect under certain conditions in which the Lundquist number is sufficiently large. The damping rate is evaluated for various plasma conditions corresponding to different parts of the solar atmosphere. The effects of viscosity are found to dominate resistivity in the quiet sun corona and solar wind.
    Keywords: SOLAR PHYSICS
    Type: Astronomy and Astrophysics (ISSN 0004-6361); 172; 1-2,; 327-331
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  • 68
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    Dynamics of solar filaments. V - Oscillations in the H-alpha and 1548 A C IV lines (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The Multichannel Subtractive Double Pass (MSDP) Spectrograph operating in the Meudon solar tower and the Ultraviolet Spectrometer and Polarimeter (UVSP) aboard the Solar Maximum Mission (SMM) satellite are used to analyze, by Fourier transform technique, time sequence observations of filaments in both the H-alpha line and in the 1548 A C IV line. The H-alpha data confirm previous findings that there are no oscillations at the location of the filament in the observed range 1-10 mHz. In the C IV line, power is observed in some parts of the filament where a steady velocity gradient is present, e.g. in the footpoints. The energy is probably due to convection motions rather than pressure oscillations.
    Keywords: SOLAR PHYSICS
    Type: Astronomy and Astrophysics (ISSN 0004-6361); 172; 1-2,
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  • 69
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    Effects of non-Maxwellian electron velocity distribution functions and nonspherical geometry on minor ions in the solar wind (1987)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A previous model has shown that in order to account for the charge state distribution in the low-speed solar wind, a high coronal temperature is necessary and that this temperature peak goes together with a peak of nx/np in the corona. In the present paper, one of the assumptions made previously, i.e., that coronal electrons are Maxwellian, is relaxed, and a much cooler model is presented, which could account for the same oxygen charge states in the solar wind due to the inclusion of non-Maxwellian electrons. Also, due to a different choice of the coronal magnetic field geometry, this model would show no enhancement of the coronal nx/np. Results of the two models are then compared, and observational tests to distinguish between the two scenarios are proposed: comparison of directly measured coronal Te to charge state measurements in the solar wind, determination of the coronal nx/np measurement of ion speeds in the acceleration region of the solar wind, and measurement of the frozen-in silicon charge state distribution.
    Keywords: SOLAR PHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 92; 1057-106
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  • 70
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    A numerical study of transient, thermally-conductive solar wind (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: A numerical analysis of transient solar wind starting at the solar surface and arriving at 1 AU is performed by an implicit numerical method. The model hydrodynamic equations include thermal conduction terms for both steady and unsteady simulations. Simulation results show significant influence of thermal conduction on both steady and time-dependent solar wind. Higher thermal conduction results in higher solar wind speed, higher temperature, but lower plasma density at 1 AU. Higher base temperature at the solar surface gives lower plasma speed, lower temperature, but higher density at 1 AU. Higher base density, on the other hand, gives lower velocity, lower temperature, but higher density at 1 AU.
    Keywords: SOLAR PHYSICS
    Type: Alabama Univ., Huntsville. STIP Symposium on Physical Interpretation of Solar(Interplanetary and Cometary Intervals; p 33
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  • 71
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    Solar activity, magnetic clouds, and geomagnetic storms (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: Associational aspects of magnetic clouds and solar activity, and of magnetic clouds and geomagentic storms are described. For example, recent research has shown associations to exist between the launch of magnetic clouds directed Earthward from the Sun and, in particular, two forms of solar activity: flare-related, type II metric radio bursts and disappearing filaments (prominences). Furthermore, recent research has shown an association to exist between the onset of magnetic clouds on Earth and the initiation of geomagnetic storms. Based on these findings, STIP Intervals XV-XIX are examined for possible occurrences of Earthward-directed magnetic clouds.
    Keywords: SOLAR PHYSICS
    Type: Alabama Univ., Huntsville. STIP Symposium on Physical Interpretation of Solar(Interplanetary and Cometary Intervals; p 30
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  • 72
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    Was the eclipse comet of 1893 a disconnected coronal transient? (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: The comet-like feature obsereved in the solar corona by the Lick Observatory eclipse expedition to Chile in 1893 bears an interesting resemblance to the disconnection coronal transient reported by Illing and Hundhausen. Reports of possibly-related limb activity are reviewed to see whether a pre-discovery observation of a relatively rare type of coronal mass ejection was mis-interpreted. The goal of this study is to learn more about the morphology of mass ejections by examining observations that extend down to the low corona of a disconnection event.
    Keywords: SOLAR PHYSICS
    Type: Alabama Univ., Huntsville. STIP Symposium on Physical Interpretation of Solar(Interplanetary and Cometary Intervals; p 27
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  • 73
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    Solar events and their influence on the interplanetary medium (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: Aspects of a workshop on Solar events and their influence on the interplanetary medium, held in September 1986, are reviewed, the goal of which was to foster interactions among colleagues, leading to an improved understanding of the unified relationship between solar events and interplanetary disturbances. The workshop consisted of three working groups: (1) flares, eruptives, and other near-Sun activity; (2) coronal mass ejections; and (3) interplanetary events. Each group discussed topics distributed in advance. The flares-eruptives group members agreed that pre-event energy is stored in stressed/sheared magnetic fields, but could not agree that flares and other eruptive events (e.g., eruptive solar prominences) are aspects of the same physical phenomenon. In the coronal mass ejection group, general agreement was reached on the presence of prominences in CMEs, and that they have a significant three-dimensional structure. Some topics identified for further research were the aftermath of CMEs (streamer deflections, transient coronal holes, possible disconnections), identification of the leading edge of CMEs, and studies of the range and prevalence of CME mass sizes and energies.
    Keywords: SOLAR PHYSICS
    Type: Alabama Univ., Huntsville. STIP Symposium on Physical Interpretation of Solar(Interplanetary and Cometary Intervals; p 29
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  • 74
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    Coronal and interplanetary Type 2 radio emission (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: Several observations suggest that the disturbances which generate coronal (meter wavelength) type II radio bursts are not driven by coronal mass ejections (CMEs). A new analysis using a large sample of metric radio bursts and associated soft X-ray events provides further support for the original hypothesis that type II-producing disturbances are blast waves generated at the time of impulsive energy release in flares. Interplanetary (IP) shocks, however, are closely associated with CMEs. The shocks responsible for IP type II events (observed at kilometer wavelengths) are associated with the most energetic CMEs.
    Keywords: SOLAR PHYSICS
    Type: Alabama Univ., Huntsville. STIP Symposium on Physical Interpretation of Solar(Interplanetary and Cometary Intervals; p 25
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  • 75
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    Coronal mass ejections: The long-term variation of their occurrence rate and the solar wind mass flux (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: Solar Coronal Mass Ejections (CMEs) from the Sun are an important aspect of coronal physics, and a potentially important contributor to the solar wind mass flux. However, despite significant progress in studies of CMEs since their discovery in the early 70's, questions remain about their effects on the interplanetary medium. A study is done of the long-term variations of the occurrence rates of CMEs, of activity tracers related to CMEs, and of the solar wind particle flux. CMEs are most directly detected by scattered electron radiation in white light. To estimate their long-term occurrence frequency and their contributions to the in-ecliptic solar wind mass flux, observed CME rates must be corrected for instrumental duty cycles, detection efficiency out of the plane of the sky, mass detection thresholds, and geometrical considerations. These corrections are evaluated using data on solar CMEs from the spaceborne Skylab, SMM, and SOLWIND coronagraphs and on interplanetary plasma clouds from the HELIOS white light photometers. Variations in the CME rate and the contribution of CMEs to the solar wind mass flux are traced over nearly a complete solar activity cycle.
    Keywords: SOLAR PHYSICS
    Type: Alabama Univ., Huntsville. STIP Symposium on Physical Interpretation of Solar(Interplanetary and Cometary Intervals; p 26
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  • 76
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    Observations of the brightness temperature distribution of the quiet solar corona at decametric wavelengths (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: The brightness temperature distribution of the quiet solar corona at a wavelength of 8.9 meters is measured by two types of radio telescope: (1) a 'T' type array with a resolution of 26'X38', and (2) a fan beam interferometer with an E-W resolution of 3'. It is found that the persistent bright regions do not have any angular structure on scales of 6' or less. The daily variations of the brightness temperature of different regions are studied and the possible interpretation discussed.
    Keywords: SOLAR PHYSICS
    Type: Alabama Univ., Huntsville. STIP Symposium on Physical Interpretation of Solar(Interplanetary and Cometary Intervals; p 23
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  • 77
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    Meterwave observations of a coronal hole (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: Meter-wave maps are presented showing a coronal hole at 30.9, 50.0, and 73.8 MHz using the Clark Lake Radioheliograph in October 1984. The coronal hole seen against the disk at all three frequencies shows interesting similarities to, and significant differences from its optical signatures in HeI lambda10830 spectroheliograms. The 73.8 MHz coronal hole, when seen near disk center, appears to coincide with the HeI footprint of the hole. At the lower frequencies, the emission comes from higher levels of the corona, and the hole appears to be displaced, probably due to the non-radial structure of the coronal hole. The contrast of the hole relative to the quiet Sun is much greater than reported previously for a coronal hole observed at 80 MHz. The higher contrast is certainly real, due to the superior dynamic range, sensitivity, and calibration of the Clark Lake instrument. Using a coronal hole model, the electron density is derived from radio observations of the brightness temperature. A very large discrepancy is found between the derived density and that determined from Skylab EUV observations of coronal holes. This discrepancy suggests that much of the physics of coronal holes has yet to be elucidated.
    Keywords: SOLAR PHYSICS
    Type: Alabama Univ., Huntsville. STIP Symposium on Physical Interpretation of Solar(Interplanetary and Cometary Intervals; p 24
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  • 78
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    Radio studies of large scale structures of the Sun's corona and transient activity (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: The use of meter-decimeter wavelength imaging observations for four different kinds of studies of solar coronal activity is discussed. (1) Large scale structure of the upper corona; daily imaging observations permit comparison of radio images with white light images from space and ground observation, generation of synoptic charts similar to white light coronagraph synoptic charts, and comparison of radio brightness enhancements and deficiencies with bright coronal streamers and coronal holes. (2) Relative positions of type III burst sources and coronal streamers as observed by Solwind experiment on the P-78-1 satellite and by the HAO C/P experiment aboard the SMM; infer the paths of type III emitting electrons in dense coronal streamers, and from multifrequency observations derive electron density distributions above active regions near the limb. (3) Non-flare associated type II/type IV bursts associated with coronal streamer disruption events; such type IV sources have a rather slow velocity (approx = to or less than 100 km/s) CMEs. (4) Meter-decimeter microbursts; these are short duration (2-10 sec) weak-type III-like bursts, produced at the fundamental plasma frequency by plasma radiation processes which have important differences from the standard mechanisms used to explain the strong type III bursts.
    Keywords: SOLAR PHYSICS
    Type: Alabama Univ., Huntsville. STIP Symposium on Physical Interpretation of Solar(Interplanetary and Cometary Intervals; p 22
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  • 79
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    On the association of erupting magnetic fields with eruptive prominences and coronal mass ejections (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: A number of space and ground-based observations give evidence that the eruptive prominences, coronal mass ejections (CMEs) and associated shocks are generated by a common cause, i.e., the eruption of the magnetic field on the Sun. Some 60% of the observed CMEs are associated with the eruptive prominences. It is believed that in reality a much better correlation should be between these events because of observational limitations and of the effect of partial eruption. Some recent results on the formation and evolution of the quiescent and the active region prominences give an idea on the early phase of eruption of the magnetic field with the prominence plasma frozen in. In the latter phase of eruption the magnetic field lifted high into the corona and is seen (as manifested by the cold plasma frozen in) as a system of huge loops - evidently the result of some reconnections at lower heights. The legs of these erupting loops interact sometimes with the local magnetic field, i.e., it often appears to be an active region. In consequence of this interaction the activation of prominences and generation of flares can take place on some occasions as well as ejection of surges and sprays.
    Keywords: SOLAR PHYSICS
    Type: Alabama Univ., Huntsville. STIP Symposium on Physical Interpretation of Solar(Interplanetary and Cometary Intervals; p 21
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  • 80
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    Solar origins of coronal mass ejections (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: The large scale properties of coronal mass ejections (CMEs), such as morphology, leading edge speed, and angular width and position, have been cataloged for many events observed with coronagraphs on the Skylab, P-78, and SMM spacecraft. While considerable study has been devoted to the characteristics of the SMEs, their solar origins are still only poorly understood. Recent observational work has involved statistical associations of CMEs with flares and filament eruptions, and some evidence exists that the flare and eruptive-filament associated CMEs define two classes of events, with the former being generally more energetic. Nevertheless, it is found that eruptive-filament CMEs can at times be very energetic, giving rise to interplanetary shocks and energetic particle events. The size of the impulsive phase in a flare-associated CME seems to play no significant role in the size or speed of the CME, but the angular sizes of CMEs may correlate with the scale sizes of the 1-8 angstrom x-ray flares. At the present time, He 10830 angstrom observations should be useful in studying the late development of double-ribbon flares and transient coronal holes to yield insights into the CME aftermath. The recently available white-light synoptic maps may also prove fruitful in defining the coronal conditions giving rise to CMEs.
    Keywords: SOLAR PHYSICS
    Type: Alabama Univ., Huntsville. STIP Symposium on Physical Interpretation of Solar(Interplanetary and Cometary Intervals; p 20
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  • 81
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    Study of pickup of cometary ions in turbulent solar winds (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: The influence of moderately strong magnetic disturbances on the ion pickup process near a comet is studied by a test-particle method. The research is motivated by recent observations with ICE and Giotto at Giacobini-Zinner and Halley. In this numerical study, the intrinsic hydromagnetic turbulence is modelled based on the Giotto and ICE data. The time evolution of the distribution function of the newborn ions is investigated. It is found that, when the level of the intrinsic turbulence is sufficiently high, the pickup ions can form a shell distribution function rapidly. The typical time scale for such a process is of the order of a couple of ion gyroperiods. On the other hand, if the turbulence is not strong, the pickup ions usually form an incomplete shell in the initial stage. The results seem to be consistent with available observations.
    Keywords: SOLAR PHYSICS
    Type: Alabama Univ., Huntsville. STIP Symposium on Physical Interpretation of Solar(Interplanetary and Cometary Intervals; p 18
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    Magnetic field twist driven by remote convective motions: Characteristics and twist rates (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: It is generally believed that convective motions below the solar photosphere induce a twist in the coronal magnetic field as a result of frozen-in physics. A question of interest is how much twist can one expect from a persistent convective motion, given the fact that dissipative effects will eventually figure. This question is examined by considering a model problem: two conducting plates, with finite resistivity, are set in sheared motion and forced at constant relative speed. A resistive plasma is between the plates and an initially vertical magnetic field connects the plates. The time rate of tilt experienced by the field is obtained as a function of Hartmann number and the resistivity ratio. Both analytical and numerical approaches are considered.
    Keywords: SOLAR PHYSICS
    Type: Alabama Univ., Huntsville. STIP Symposium on Physical Interpretation of Solar(Interplanetary and Cometary Intervals; p 17
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    Comparison of MHD simulation for the February 1986 events with interplanetary observations by the spacecraft Sakigake (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: During the period 3-10 February 1986 a series of major solar flares occurred on the Sun and several intense geomagnetic storms took place on the Earth. To examine the causality between the solar activity and the geomagnetic activity in this period, a magnetohydrodynamic (MHD) numerical simulation was performed using a 2 1/2 -D numerical code. In that period of February 1986, the Japanese spacecraft Sakigake was at 0.84 AU, 57 deg west of the Earth. Besides the in-situ measurements of the interplanetary plasma, Sakigake also provided Doppler scintillation observations. Comparisons between the results of the MHD simulation and the measurements made by the spacecraft Sakigake are presented.
    Keywords: SOLAR PHYSICS
    Type: Alabama Univ., Huntsville. STIP Symposium on Physical Interpretation of Solar(Interplanetary and Cometary Intervals; p 15
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  • 84
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    Two dimensional imaging observations of meter-decameter bursts associated with the February 1986 flare activity (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: An analysis is presented of the two dimensional imaging observations of a flare observed on 3 Feb. l986 using the Clark Lake Multifrequency Radioheliograph. The flare produced almost all types of Meter-decimeter radio emission: enhanced storm radiation, type III/V bursts, II and IV and flare continuum. The flare continuum had early (FCE) and late (FC II) components and the type II occurred during the period between these two components. Comparing the source positions of type III/V and FCE it was found that these bursts must have occurred along adjacent open and closed field lines, respectively. The positional analysis of type II and FC II implies that the nonthermal electrons responsible for FC II need not be accelerated by type II shock and this conclusion is further supported by the close association of FC II with a microwave peak. Using the positional and temporal analysis of all these bursts and the associated hard X-ray and microwave emissions, a schematic model is developed for the magnetic field configuration in the flaring region in which the nonthermal particles responsible for these bursts are confined or along which they propagate.
    Keywords: SOLAR PHYSICS
    Type: Alabama Univ., Huntsville. STIP Symposium on Physical Interpretation of Solar(Interplanetary and Cometary Intervals; p 16
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  • 85
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    Evolution of the solar wind structure in the outer heliosphere (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: Shocks and interaction regions play very important roles in the evolution of large-scale solar wind structure in the outer heliosphere. This study is based on (1) plasma and magnetic field data observed from Voyager and Pioneer spacecraft, and (2) a quantitative magnetohydrodynamic simulation model. Interaction regions bounded by a forward and a reverse shock begin to form near 1 AU at the leading edges of a large-scale stream. The total pressure in the region is greater than the ambient pressure by a factor of ten or more. Large jumps in pressure remain as a prominant feature of the interplanetary structure even as the jumps in flow speed become less visible in the outer heliosphere. The propagation of the forward and reverse shocks widens the dimension of an interaction region. As a result, two interaction regions belonging to neighboring streams coalesce to form a merged interaction region (MIR). Collision and merging of shocks take place during the coalescence process. Two MIRs can themselves merge again at greater heliocentric distances. Simulation results agree well with spacecraft observations, and they explain major restructuring of the solar wind in the outer heliosphere.
    Keywords: SOLAR PHYSICS
    Type: Alabama Univ., Huntsville. STIP Symposium on Physical Interpretation of Solar(Interplanetary and Cometary Intervals; p 14
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  • 86
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    Solar modulation of the cosmic radiation in the heliosphere (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: Changes in the solar modulation of galactic and anomalous component cosmic rays reflect changes in the structure and magnetic topology of the interplanetary medium. Therefore, to the extent that the modulation process is understood, the cosmic rays can be used as a probe of the medium to infer the extent and structure of the heliosphere in regions not directly sampled by spacecraft. The challenge to modulation theory and observation has been to determine which properties of the solar wind are most important for producing the observed modulation. Significant progress has been made in answering this question during the last solar cycle using observations from spacecraft at radii to 40 AU from the Sun and at latitudes up to 30 degrees with respect to the ecliptic. A brief summary of new results and observations (with specific attention to the STIP intervals XV-XIX) will be presented to illustrate the present state of our understanding of the relation between the solar wind and interplanetary magnetic field and the modulations of the cosmic radiation.
    Keywords: SOLAR PHYSICS
    Type: Alabama Univ., Huntsville. STIP Symposium on Physical Interpretation of Solar(Interplanetary and Cometary Intervals; p 13
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  • 87
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    Change in interplanetary shock acceleration preceding STIP Interval 17 (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: The intensity and frequency of shock acceleration events in the interplanetary medium decreased dramatically in early 1985. Low energy ions were observed by IMP 8 at 1 AU and Voyagers 1 and 2 at 22 and 16 AU, respectively. Voyager 1 was at 25 deg heliographic latitude while IMP 8 and Voyager 2 were near the solar equatorial plane. The decrease in low energy shock events led to a drop in the average ion flux by a factor of 20 to 50. It started about day 10 of 1985 in the approximately .5 MeV channel on IMP8 and took approximately 75 days to reach the new, lower, background level. The decrease at the Voyagers started approximately 50 days later. The time delay between the start of the decrease at IMP and at Voyager 2 implies that decrease was convected outward with a velocity of approximately 535 km/sec. The intensity and frequency of interplanetary shock events remained at the lower level for at least 1.5 years.
    Keywords: SOLAR PHYSICS
    Type: Alabama Univ., Huntsville. STIP Symposium on Physical Interpretation of Solar(Interplanetary and Cometary Intervals; p 12
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  • 88
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    Propagating shocks in the corona (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: High resolution observations performed with the Decimeter spectrograph and the multichannel receiver at Nancay were analyzed in the range of 25-75 MHz. Sixty Type II bursts were selected. In this frequency range, type II events are generally associated with other radio emissions (such as storms of type III-U-I bursts); they are preceeded or followed by groups of U-bursts. One third of type II events show a nonuniform frequency drift, usually a steep decrease followed by an abrupt increase. This phenomenon can be explained by the propagation of an extended disturbance through the ambient corona when the density gradient is enhanced. An empirical coronal model is proposed to interpret these observations. The observations at fixed frequency of Type II bursts including fundamental and harmonic components are analyzed. It is shown that the spectrum of the intensity fluctuations differs with the fundamental and the harmonic components. The origin of these differences is discussed.
    Keywords: SOLAR PHYSICS
    Type: Alabama Univ., Huntsville. STIP Symposium on Physical Interpretation of Solar(Interplanetary and Cometary Intervals; p 11
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  • 89
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    Protostellar disks and the primitive solar nebula (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: The objective is to obtain quantitative information on the turbulent transport of mass, angular momentum, and energy under the conditions that characterize the solar nebula, by direct numerical calculations. These calculations were made possible by research conducted on supercomputers (Cray XMP and Cray 2) by the Ames Computational Fluid Dynamics Branch. Techniques were developed that permitted the accurate representation of turbulent flows over the full range of important eddy sizes. So far, these techniques were applied (and verified) primarily in mundane laboratory situations, but they have a strong potential for astrophysical applications. A sequence of numerical experiments were conducted to evaluate the Reynold's stress tensor, turbulent heat transfer rate, turbulent dissipation rate, and turbulent kinetic energy spectrum, as functions of position, for conditions relevant to the solar nebula. Emphasis is placed on the variation of these properties with appropriate nondimensional quantities, so that relations can be derived that will be useful for disk modeling under a variety of hypotheses and initial conditions.
    Keywords: SOLAR PHYSICS
    Type: NASA, Washington, Reports of Planetary Geology and Geophysics Program, 1986; p 97-99
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  • 90
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    Intelligent fault-tolerant controllers (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: A system with fault tolerant controls is one that can detect, isolate, and estimate failures and perform necessary control reconfiguration based on this new information. Artificial intelligence (AI) is concerned with semantic processing, and it has evolved to include the topics of expert systems and machine learning. This research represents an attempt to apply AI to fault tolerant controls, hence, the name intelligent fault tolerant control (IFTC). A generic solution to the problem is sought, providing a system based on logic in addition to analytical tools, and offering machine learning capabilities. The advantages are that redundant system specific algorithms are no longer needed, that reasonableness is used to quickly choose the correct control strategy, and that the system can adapt to new situations by learning about its effects on system dynamics.
    Keywords: CYBERNETICS
    Type: NASA. Langley Research Center Joint University Program for Air Transportation Research, 1984; p 149-160
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  • 91
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    Task-level robot programming: Integral part of evolution from teleoperation to autonomy (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: An explanation is presented of task-level robot programming and of how it differs from the usual interpretation of task planning for robotics. Most importantly, it is argued that the physical and mathematical basis of task-level robot programming provides inherently greater reliability than efforts to apply better known concepts from artificial intelligence (AI) to autonomous robotics. Finally, an architecture is presented that allows the integration of task-level robot programming within an evolutionary, redundant, and multi-modal framework that spans teleoperation to autonomy.
    Keywords: CYBERNETICS
    Type: NASA. Lyndon B. Johnson Space Center, Houston, Texas, First Annual Workshop on Space Operations Automation and Robotics (SOAR 87); p 533-540
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  • 92
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    An efficient representation of spatial information for expert reasoning in robotic vehicles (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: The previous generation of robotic vehicles and drones was designed for a specific task, with limited flexibility in executing their mission. This limited flexibility arises because the robotic vehicles do not possess the intelligence and knowledge upon which to make significant tactical decisions. Current development of robotic vehicles is toward increased intelligence and capabilities, adapting to a changing environment and altering mission objectives. The latest techniques in artificial intelligence (AI) are being employed to increase the robotic vehicle's intelligent decision-making capabilities. This document describes the design of the SARA spatial database tool, which is composed of request parser, reasoning, computations, and database modules that collectively manage and derive information useful for robotic vehicles.
    Keywords: CYBERNETICS
    Type: NASA. Lyndon B. Johnson Space Center, Houston, Texas, First Annual Workshop on Space Operations Automation and Robotics (SOAR 87); p 527-531
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  • 93
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    Real-time artificial intelligence issues in the development of the adaptive tactical navigator (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: Adaptive Tactical Navigation (ATN) is a laboratory prototype of a knowledge based system to provide navigation system management and decision aiding in the next generation of tactical aircraft. ATN's purpose is to manage a set of multimode navigation equipment, dynamically selecting the best equipment to use in accordance with mission goals and phase, threat environment, equipment malfunction status, and battle damage. ATN encompasses functions as diverse as sensor data interpretation, diagnosis, and planning. Real time issues that were identified in ATN and the approaches used to address them are addressed. Functional requirements and a global architecture for the ATN system are described. Decision making with time constraints are discussed. Two subproblems are identified; making decisions with incomplete information and with limited resources. Approaches used in ATN to address real time performance are described and simulation results are discussed.
    Keywords: CYBERNETICS
    Type: NASA. Lyndon B. Johnson Space Center, Houston, Texas, First Annual Workshop on Space Operations Automation and Robotics (SOAR 87); p 389-396
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  • 94
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    TDAS: The Thermal Expert System (TEXSYS) data acquisition system (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: As part of the NASA Systems Autonomy Demonstration Project, a thermal expert system (TEXSYS) is being developed. TEXSYS combines a fast real time control system, a sophisticated human interface for the user and several distinct artificial intelligence techniques in one system. TEXSYS is to provide real time control, operations advice and fault detection, isolation and recovery capabilities for the space station Thermal Test Bed (TTB). TEXSYS will be integrated with the TTB and act as an intelligent assistant to thermal engineers conducting TTB tests and experiments. The results are presented from connecting the real time controller to the knowledge based system thereby creating an integrated system. Special attention will be paid to the problem of filtering and interpreting the raw, real time data and placing the important values into the knowledge base of the expert system.
    Keywords: CYBERNETICS
    Type: First Annual Workshop on Space Operations Automation and Robotics (SOAR 87); p 375-382
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  • 95
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    A conceptual framework for intelligent real-time information processing (1987)
    In:  CASI
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    Publication Date: 2013-08-31
    Description: By combining artificial intelligence concepts with the human information processing model of Rasmussen, a conceptual framework was developed for real time artificial intelligence systems which provides a foundation for system organization, control and validation. The approach is based on the description of system processing terms of an abstraction hierarchy of states of knowledge. The states of knowledge are organized along one dimension which corresponds to the extent to which the concepts are expressed in terms of the system inouts or in terms of the system response. Thus organized, the useful states form a generally triangular shape with the sensors and effectors forming the lower two vertices and the full evaluated set of courses of action the apex. Within the triangle boundaries are numerous processing paths which shortcut the detailed processing, by connecting incomplete levels of analysis to partially defined responses. Shortcuts at different levels of abstraction include reflexes, sensory motor control, rule based behavior, and satisficing. This approach was used in the design of a real time tactical decision aiding system, and in defining an intelligent aiding system for transport pilots.
    Keywords: CYBERNETICS
    Type: NASA. Lyndon B. Johnson Space Center, Houston, Texas, First Annual Workshop on Space Operations Automation and Robotics (SOAR 87); p 371-374
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  • 96
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    Beyond rules: The next generation of expert systems (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: The PARAGON Representation, Management, and Manipulation system is introduced. The concepts of knowledge representation, knowledge management, and knowledge manipulation are combined in a comprehensive system for solving real world problems requiring high levels of expertise in a real time environment. In most applications the complexity of the problem and the representation used to describe the domain knowledge tend to obscure the information from which solutions are derived. This inhibits the acquisition of domain knowledge verification/validation, places severe constraints on the ability to extend and maintain a knowledge base while making generic problem solving strategies difficult to develop. A unique hybrid system was developed to overcome these traditional limitations.
    Keywords: CYBERNETICS
    Type: NASA. Lyndon B. Johnson Space Center, Houston, Texas, First Annual Workshop on Space Operations Automation and Robotics (SOAR 87); p 363-369
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  • 97
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    Automatic routing module (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: Automatic Routing Module (ARM) is a tool to partially automate Air Launched Cruise Missile (ALCM) routing. For any accessible launch point or target pair, ARM creates flyable routes that, within the fidelity of the models, are optimal in terms of threat avoidance, clobber avoidance, and adherence to vehicle and planning constraints. Although highly algorithmic, ARM is an expert system. Because of the heuristics applied, ARM generated routes closely resemble manually generated routes in routine cases. In more complex cases, ARM's ability to accumulate and assess threat danger in three dimensions and trade that danger off with the probability of ground clobber results in the safest path around or through difficult areas. The tools available prior to ARM did not provide the planner with enough information or present it in such a way that ensured he would select the safest path.
    Keywords: CYBERNETICS
    Type: NASA. Lyndon B. Johnson Space Center, Houston, Texas, First Annual Workshop on Space Operations Automation and Robotics (SOAR 87); p 327-334
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  • 98
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    Advanced decision aiding techniques applicable to space (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: RADC has had an intensive program to show the feasibility of applying advanced technology to Air Force decision aiding situations. Some aspects of the program, such as Satellite Autonomy, are directly applicable to space systems. For example, RADC has shown the feasibility of decision aids that combine the advantages of laser disks and computer generated graphics; decision aids that interface object-oriented programs with expert systems; decision aids that solve path optimization problems; etc. Some of the key techniques that could be used in space applications are reviewed. Current applications are reviewed along with their advantages and disadvantages, and examples are given of possible space applications. The emphasis is to share RADC experience in decision aiding techniques.
    Keywords: CYBERNETICS
    Type: NASA. Lyndon B. Johnson Space Center, Houston, Texas, First Annual Workshop on Space Operations Automation and Robotics (SOAR 87); p 321-326
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  • 99
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    Robotic planner expert system (RPLANES) (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: The Artificial Intelligence Section of the Mission Planning and Analysis of the Johnson Space Center has developed a prototype of an expert system for robotic planning. A robot is given a high level goal to perform an action (i.e., swap, adjust, or stow) on a component unit of an object such as a satellite and the Robotic Planner Expert System (RPLANES) generates the necessary goals for arm actions. RPLANES is designed using the Inference Corp. Automated Reasoning Tool (ART) development tool. It resides on a SYMBOLICS 3670. RPLANES and its evolution are described.
    Keywords: CYBERNETICS
    Type: First Annual Workshop on Space Operations Automation and Robotics (SOAR 87); p 293-297
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  • 100
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    Artificial Intelligence (AI), Operations Research (OR), and Decision Support Systems (DSS): A conceptual framework (1987)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: In recent years there has been increasing interest in applying the computer based problem solving techniques of Artificial Intelligence (AI), Operations Research (OR), and Decision Support Systems (DSS) to analyze extremely complex problems. A conceptual framework is developed for successfully integrating these three techniques. First, the fields of AI, OR, and DSS are defined and the relationships among the three fields are explored. Next, a comprehensive adaptive design methodology for AI and OR modeling within the context of a DSS is described. These observations are made: (1) the solution of extremely complex knowledge problems with ill-defined, changing requirements can benefit greatly from the use of the adaptive design process, (2) the field of DSS provides the focus on the decision making process essential for tailoring solutions to these complex problems, (3) the characteristics of AI, OR, and DSS tools appears to be converging rapidly, and (4) there is a growing need for an interdisciplinary AI/OR/DSS education.
    Keywords: CYBERNETICS
    Type: NASA. Lyndon B. Johnson Space Center, Houston, Texas, First Annual Workshop on Space Operations Automation and Robotics (SOAR 87); p 287-292
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