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  • 1
    Electronic Resource
    Electronic Resource
    Ein alternativer Weg zur Darstellung von Bi2Sr2CaCu2Ox, YBa2Cu3O7-δ, und YBa2Cu3-xMxO7-δ (M = Ni, Ag und x ≤ 33 Mol%)Professor Rudolf Hoppe zum 70. Geburtstage gewidmet (1992)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 616 (1992), S. 186-190 
    Details
    ISSN: 0044-2313
    Keywords: Preparation of quaternary copper oxides ; high Tc superconductors ; characterization by X-ray powder methods ; AC- and DC-susceptibility ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: An Alternative Method for Preparation of Bi2Sr2CaCu3Ox, YBa2Cu3O7-δ, and YBa2Cu3-xMxO7-δ (M = Ni, Ag and x ≤ 33 Mol%)Oxidation of quenched melts of metals in a well defined argon/oxygen atmosphere has been found as an alternative method to prepare hight purity samples of Bi2Sr2CaCu2Ox without Pb-stabilization. A special equipment for the oxidation of powder samples will be described. By our new method it is also possible to prepare YBa2Cu3O7-δ and derivatives of this compound, where Cu is substituted by high amounts of Ni or Ag.
    Notes: Es wird eine alternative Präparationsmethode beschrieben, die es ermöglicht, durch Oxidation abgeschreckter Metallschmelzen in einer Sauerstoff-Argon-Strömungsapparatur sehr saubere, nicht Pb-stabilisierte Bi2Sr2CaCu2Ox-Präparate herzustellen. Dieser Weg ist auch für die Darstellung von YBa2Cu3O7-δ und Substitutionsderivaten dieser Verbindung mit hohen Konzentrationen an Ni oder Ag geeignet.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19926161030
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    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Spherulite boundary strengthening concept for toughening polypropylene (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 2047-2056 
    Details
    ISSN: 0887-6266
    Keywords: polypropylene ; spherulite ; cocrystallization ; lamellae ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: During spherulitic crystallization of polymers, there is a tendency for low molecular weight and other less crystallizable entities to be rejected from the body of the spherulites. This rejection process causes a segregation of these species to those areas where spherulites impinge. As a result of this segregation, lamellar and spherulite boundaries have a tendency to become weak, often resulting in premature mechanical failure. The objective of this work, anthropomorphically speaking, is to develop a melt miscible blend system in which a propylene copolymer “fools” a polypropylene homopolymer into rejecting the copolymer to the spherulite boundaries as an impurity. However, once the copolymer arrives at these boundaries, the copolymer subsequently connects adjacent spherulites through cocrystallization of the propylene copolymer segments. It was found that addition of either a random ethylene-propylene copolymer or an isotactic-atactic block copolymer was able to yield the desired effect. Cocrystallization was confirmed by calorimetry, and segregation of copolymer and subsequent reinforcement at the spherulite boundaries was directly observed microscopically. Using this approach, toughness was increased with little loss in stiffness. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 2047-2056, 1998
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 3
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    Design and analysis of a low-loss linear analog phase modulator for deep space spacecraft X-band transponder applications (1991)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: This article summarizes the design concepts, analyses, and development of an X-band (8145 MHz) transponder low-loss linear phase modulator for deep space spacecraft applications. A single-section breadboard circulator-coupled reflection phase modulator has been analyzed, fabricated, and evaluated. A linear phase deviation of 92 deg with a linearity tolerance of +/- 8 percent was measured for this modulator from 8257 MHz to 8634 MHz over the temperature range -20 to 75 C. The measured insertion loss and the static delay variation with temperature were 2 +/- 0.3 dB and 0.16 psec/ C, respectively. Based on this design, cascaded sections have been modeled, and simulations were performed to provide an X-band deep space transponder (DST) phase modulator with +/- 2.5 radians (+/- 143 deg) of peak phase deviation to accommodate downlink signal modulation with composite telemetry data and ranging, with a deviation linearity tolerance of +/- 8 percent and insertion loss of less than 10 +/- 0.5 dB. A two-section phase modulator using constant gamma hyperabrupt varactors and an efficient modulator driver circuit was breadboarded. The measured results satisfy the DST phase-modulator requirements and show excellent agreement with the predicted results.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Telecommunications and Data Acquisition Report; p 136-145
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 4
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    Performance results of a 300-degree linear phase modulator for spaceborne communications applications (1993)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A phase modulator capable of large linear phase deviation, low loss, and wide band operation with good thermal stability was developed for deep space spacecraft transponder (DST) applications at X-band (8.415 GHz) and Ka-band (32 GHz) downlinks. The design uses a two-stage circulator-coupled reflection phase shifter with constant gamma hyperabrupt varactors and an efficient modulator driver circuit to obtain a phase deviation of +/-2.5 rad with better than 8 percent linearity. The measured insertion loss is 6.6 dB +/- 0.35 dB at 8415 MHz. Measured carrier and relative sideband amplitudes resulting from phase modulation by sine wave and square modulating functions agree well with the predicted results.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Telecommunications and Data Acquisition Report; p 107-116
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 5
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    Propagation along azimuthally magnetized ferrite-loaded circular waveguides (1977)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: The paper describes the modal dispersion characteristics of electromagnetic waves traveling along the azimuthally magnetized ferrite-loaded coaxial transmission line and the ferrite-loaded wire. The modal dispersion curves are used to determine the pass and stop bands of normal propagation. Boundary-value problems were solved with Bolle-Heller functions. The dispersion characteristics of transverse electric modes are presented as plots of the normalized propagation constant vs the normalized frequency.
    Keywords: COMMUNICATIONS AND RADAR
    Type: Journal of Applied Physics; 48; June 197
    Format: text
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  • 6
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    VHF downline communication system for SLAR data (1979)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: A real time VHF downlink communication system is described for transmitting side-looking airborne radar (SLAR) data directly from an aircraft to a portable ground/shipboard receiving station. Use of this receiving station aboard the U.S. Coast Guard icebreaker Mackinaw for generating real-time photographic quality radar images is discussed. The system was developed and demonstrated in conjunction with the U.S Coast Guard and NOAA National Weather Service as part of the Project Icewarn all weather ice information system for the Great Lakes Winter Navigation Program.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NASA-TM-79164 , E-025 , Intern. Symp. on Remote Sensing of Environment; Apr 23, 1979 - Apr 27, 1979; Ann Arbor, MI; United States
    Format: application/pdf
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