A Unified Approach to Model-Reference Adaptive Systems Part I: Theory

A unified approach to model-reference adaptive control systems is presented. A linearized error equation for each adaptive system is derived about some operating point and converted into the standard form for plotting root loci. The contribution made here is to convert the selection of an adaptive technique and the choosing of adaptive coefficients for some desired system performance from a "mystical art" to standard control techniquess.     

Responses of the upper middle atmosphere (60–110 km) to the stratwarms of the four pre-map winters (1978/9–1981/2)

The global developments of the four stratospheric events (～20–50 km) are described, using balloon, satellite and rocket data. Winds data for heights of 60–95 km, derived from L.F. drift (52°N, 15°E; Europe) and M.F. radar (52°N, 107°W; Canada), are then compared with the stratospheric data. There is clear evidence that the preliminary planetary waves often penetrate strongly to ～90 km, and that mean wind reversals also occur. However, there are dramatic differences between European and Canadian mesospheric responses.     

Thin-film Li-LiMn2O4 batteries

Thin-film rechargeable Li-LiMn₂O₄ batteries have been fabricated and characterized. Following deposition by electron beam evaporation of LiMn₂O₄, the amorphous as-deposited cathode films 1 cm² in area by 0.3to 4-μm thick were annealed at 700°C to 800°C in oxygen in order to form the crystalline spinet phase. The specific capacity of the cells between 4.5 V to 3.8 V ranged from 50 μAh/mg to 120 μAh/mg. When cycled over this range, the batteries exhibited excellent secondary performance with capacity losses as low as 0.001% per cycle. On charging to 5.3 V, a plateau with a median voltage of 5.1 V was observed. The total charge extracted between 3.8 V to 5.3 V corresponded to about 1 Li/Mn₂ O₄     

IUE and Einstein observations of supernovae

In this paper IUE observations of two type II and three type I Supernovae (see Table I and Table II) are reviewed. The type II events were also observed by Einstein and SN 1980k was detected in the soft X-ray energy band. Combining UV spectra available of the same events one has the elements to construct a physical picture which accounts for all observations. For the type II events it appears that the progenitor star was a massive supergiant which underwent a severe mass loss before becoming Supernova. For the type I events there is neither X-ray nor, for the time being, radio detection. The high similarity of the optical and UV spectra for the three events indicates that type I Supernovae are the end products of one and the same phenomenon.     

Preflare heating of filaments

Disappearances of preflare filaments have been observed on June 22, 1980 (S07,W13) (flare at 13.04 U.T.) and September 3, 1980 (flare at 7.52 U.T.). The analysis of MSDP data (MEUDON) leads to the followings conclusions : - Disappearances begin a few minutes before the Hα impulsive phase. - The filaments can be seen again after the flares. - Upwards motions occur in several points, without disturbing significantly preëxisting downflows.Velocity maps suggest shears or velocity loops.The filament disappearance seems to be due to a heating mechanism beginning before the flare maximum.     

The Magellan project

Magellan is one of the future space projects being studied by the European Space Agency. The aim is to provide high resolution (λ/Δλ ≥ 2.5 × 10⁴) spectra in the far and extreme UV (between 500 and 1550 Å) of faint galactic and extragalactic objects (V ≤ 16^m). The instrument consists of a mechanical collimator, a concave holographic grating and a bidimensional photon-counting detector. A low resolution mode (λ/Δλ ≥ 10³) will provide spectra of objects as faint as 18^m.5. Magellan is planned as an observatory, operated in real time, and allowing interaction with the observer.     

Structure of the Martian atmosphere from ε-Gem occultation observations

We have collected information about Martian atmospheric scale heights derived from observations of the occultation of ? Gem by Mars on April 8, 1976. The observations give data in the altitude range ～50 to 80 km. A rough, unweighted average of results so far available yields a temperature of ～165°K. Excursions of ～±40°K about this mean may be present as a function of both altitude and areographic coordinates.     

Impact linear polarization observed in a UV chromospheric line during a solar flare

Linear polarization was observed in the S I 1437Å line in bright flaring points during the soft X-ray emission. The degree of polarization is about 25% and is detected at a signal to noise ratio of 2.9. The polarized electric vector is directed towards disk center to within 3°.This polarization could be due to collisional excitationm of S I by energetic electrons beamed in the vertical direction. We suggest that the heat flux in the region interconnecting the transition zone to the high chromosphere during the gradual phase of a flare could lead to an anisotropic excitation. Then the observed polarization would be due to vertical motions of the transition zone sweeping the preexisting chromosphere.     

Comet nucleus sample return: Plans and capabilities

ROSETTA — the Comet Nucleus Sample Return mission — is one of the four Cornerstone missions to which ESA has committed itself in its approved Long-Term Programme Horizon 2000. The mission is currently being studied in collaboration with NASA. The comet-nucleus samples that ROSETTA is to provide will allow us to study some of the most primitive material in the solar system and the physical and chemical processes that marked the beginning of the system 4.6 billion years ago. For ESA, ROSETTA is a new type of mission: one which will return a sample at cryogenic temperature, and where as much effort has to be spent on preparing the laboratory analysis on-ground as has to be invested in preparing the space segment with the sample acquisition and in situ documentation. As part of the preparation for this mission, ESA is now starting to consider Planetary Protection issues.     

Applications of aluminum-air batteries

Advances in aluminum-air batteries are described. These include alloys that show higher efficiencies and therefore lower hydrogen evolution, low-cost air cathodes that can be fabricated in production quantities, and methods for handling the aluminum hydroxide reaction product. Emphasis is placed on the advances in air cathodes. The application of this technology to new products and the implications for electric vehicles are discussed