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  • 1
    ISSN: 0992-7689
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract A discussion is given of plasma flows in the dawn and nightside high-latitude ionospheric regions during substorms occurring on a contracted auroral oval, as observed using the EISCAT CP-4-A experiment. Supporting data from the PACE radar, Greenland magnetometer chain, SAMNET magnetometers and geostationary satellites are compared to the EISCAT observations. On 4 October 1989 a weak substorm with initial expansion phase onset signatures at 0030 UT, resulted in the convection reversal boundary observed by EISCAT (at \sim0415 MLT) contracting rapidly poleward, causing a band of elevated ionospheric ion temperatures and a localised plasma density depletion. This polar cap contraction event is shown to be associated with various substorm signatures; Pi2 pulsations at mid-latitudes, magnetic bays in the midnight sector and particle injections at geosynchronous orbit. A similar event was observed on the following day around 0230 UT (\sim0515 MLT) with the unusual and significant difference that two convection reversals were observed, both contracting poleward. We show that this feature is not an ionospheric signature of two active reconnection neutral lines as predicted by the near-Earth neutral model before the plasmoid is “pinched off”, and present two alternative explanations in terms of (1) viscous and lobe circulation cells and (2) polar cap contraction during northward IMF. The voltage associated with the anti-sunward flow between the reversals reaches a maximum of 13 kV during the substorm expansion phase. This suggests it to be associated with the polar cap contraction and caused by the reconnection of open flux in the geomagnetic tail which has mimicked “viscous-like” momentum transfer across the magnetopause.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 61 (1990), S. 1658-1663 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A simple, endoscopic automatic vision system, using white-light illumination has been designed and is discussed. Results of an application to the monitoring of the laying of an adhesive strip in a robotically operated product assembly are illustrated.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1573-4846
    Keywords: II–VI semiconductor ; ultrasounds ; quantum dots ; nanoparticles ; DCCA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract SiO2 gels obtained by sonocatalytic method combined with DCCA were used as host-matrices for extremely fine dispersions of CdS semiconductor particles. Small crystallites were produced “in situ” by H2S gas diffusion method. The particles were characterized by TEM and HRTEM, EXAFS, UV-Vis and Raman spectroscopies. The size of crystallites ranged from 5 to 10 nm. The optical transmission spectra showed the characteristic blue shift as a function of the particles size, as predicted by the theory. The optical and mechanical qualities of the samples were substantially improved by an infiltration method using a sono-sol which sealed the superficial pores thus ensuring greater longevity and the possibility of obtaining transparent gels by polishing.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Journal of sol gel science and technology 2 (1994), S. 347-352 
    ISSN: 1573-4846
    Keywords: zirconia ; sintering ; densification ; heat treatment ; yttria stabilized zirconia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Amorphous zirconia ceramics powders containing 3 and 6 mol% yttria were prepared by controlled hydrolysis of alkoxides. Characterization of these powders was carried away by Thermal Analysis, X-ray Diffraction, Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Analysis (EDAX™). The calcination temperature was optimized for compaction at a temperature ranging from 500–800°C. 3% molar YSZ powders from alkoxide, that attained 98% of the theoretical bulk density, showed the best behaviour.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Zeitschrift für angewandte Mathematik und Physik 28 (1977), S. 1017-1026 
    ISSN: 1420-9039
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Description / Table of Contents: Zusammenfassung Es werden einige Einschränkungen für die Randbedingungen in der Kontinuumsmechanik behandelt, die von der Forderung herrühren, dass für die Materie ausserhalb der Grenzfläche die fundamentalen Bilanzgleichungen, die Invarianzbedingungen und die Entropieungleichung gelten sollen. Diese Behauptungen werden für polare Materialien erläutert, jedoch sind die hier eingeführten Begriffe auf Kontinuumstheorien aller Art anwendbar.
    Notes: Summary We discuss some restrictions on boundary conditions in continuum mechanics arising from the requirement that the basic balance laws, invariance conditions and entropy inequality must hold for the material outside of the bounding surface. We illustrate our assertions for polar materials, but the ideas we use are applicable to all continuum theories.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Rheologica acta 16 (1977), S. 213-222 
    ISSN: 1435-1528
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Zusammenfassung Das Isotop Helium 4 unter 2,2°K, bekannt als Helium II, zeigt einige merkwürdige mechanische und thermische makroskopische Effekte. In dieser Arbeit wird eine mögliche Alternative zu der Zweiflüssigkeitentheorie für Helium II besprochen. Standardmethoden der Kontinuumsmechanik werden benutzt, um den Fluß gewisser mikroskopischer Anregungszustände zu beschreiben, die als Ursache der beobachteten Effekte angesehen werden. Passende Bilanzgleichungen werden aufgestellt und Stoffgleichungen vorgeschlagen. Einige einfache Lösungen der sich ergebenden Theorie werden diskutiert, die qualitative Übereinstimmung mit den beobachteten Effekten liefern. Diese Effekte betreffen das Experiment der hängenden Platte von Hall, den Springbrunneneffekt und Schall-Wellen zweiter Art bei kleinen Amplituden.
    Notes: Summary The isotope helium 4 below 2.2°K, known as helium II, exhibits a number of curious mechanical and thermal macroscopic effects. In this paper a possible alternative to the two-fluid theory for helium II is reviewed. Standard techniques of continuum mechanics are used to describe the flow of certain microscopic excitations which are believed to give rise to the observed effects. Appropriate balance laws are formulated and constitutive equations are proposed. Some simple solutions of the resulting theory are discussed which give qualitative agreement with observed effects. These effects include Hall's hanging plate experiment, the fountain effect and smallamplitude second-sound waves.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Solar physics 152 (1994), S. 1-8 
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The Cryogenic Solar Absolute Radiometer (CSAR) is a new primary radiometric standard for use in space traceable to the International. System of Units (SI). CSAR will have the potential to measure the total irradiance of the Sun with an uncertainty of 0.01% and a resolution of 0.001%, more than a factor ten improvement over existing instruments. Since CSAR will be cooled by a mechanical cooler based upon the Stirling cycle its working lifetime is projected to be in excess of 10 years.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Journal of elasticity 5 (1975), S. 237-248 
    ISSN: 1573-2681
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Standard techniques of continuum mechanics are used to describe the flow of certain microscopic excitations which are believed to give rise to the second-sound phenomena in some materials at low temperatures. Appropriate balance laws are formulated, and constitutive equations for an elastic solid are postulated. The propagation of small-amplitude second-sound waves is discussed and the results compared with those predicted by the theory of Lord and Shulman [1].
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Acta mechanica 21 (1975), S. 221-239 
    ISSN: 1619-6937
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Description / Table of Contents: Zusammenfassung Unter Verwendung der vonGreen andRivlin [1] angegebenen allgemeinen Theorie multipolarer Werkstoffe wird eine mögliche Alternative zu den Zweiphasentheorien von flüssigem Helium II diskutiert. Im speziellen wird die Existenz von Wellen mit zweiter Schallgeschwindigkeit, die in der, in stationärer wie auch in rotierender Flüssigkeit beobachteten Art abgemindert werden. Weiters wird eine mögliche Analogie des Konzepts einer gequantelten Wirbellinie vorgeschlagen.
    Notes: Summary Using the general framework of multipolar continuum mechanics as developed byGreen andRivlin [1], we discuss a possible alternative to the two-fluid theories of liquid helium II. We show in particular that our theory predicts the existence of second-sound waves which are attenuated in the manner obseved both in the stationary fluid and also in the rotating fluid. Moreover we suggest a possible continuum analogue of the concept of quantised vortex lines.
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Journal of materials science 10 (1991), S. 1237-1242 
    ISSN: 1573-4811
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
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