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  • 1
    Electronic Resource
    Electronic Resource
    The Kapitza Conductance of Metal Single Crystals by the Second Sound Technique (1975)
    Springer
    Journal of low temperature physics 20 (1975), S. 181-206 
    Details
    ISSN: 1573-7357
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: We have determined the Kapitza conductance h K of high-purity single crystals of gallium, copper, lead, and tin, between 1.2 and 2 K, by an improved version of the second sound method developed by Challis and Sherlock.1 By using a special mounting technique, we were able to avoid strains in the samples on cooling. A comparison of our results with those given in the literature shows that our values of h K are consistently higher than those obtained by using the steady-state method. By introducing different amounts of strain in a given sample we were able to reduce its h K by corresponding amounts. Thus we were able to cover, for a given metal, the entire range of reported steady-state values. We were also able to demonstrate that in the region of 1–2 K strain not only reduces h K but also increases the temperature dependence considerably. Although a reduction of h K with strain has been reported with the steady-state measurements, it is not accompanied by an increase in the temperature dependence. Possible reasons for this are discussed. Our study of the superconductors lead and tin shows that the temperature exponent is nearly the same in the superconducting and normal states. The absolute value of h K decreases in lead typically by 6 % and increases in tin by 5 %.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00115263
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    Paper (German National Licenses)
    Fulltext
  • 2
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    Unknown
    Measurement techniques and instruments suitable for life-prediction testing of photovoltaic arrays (1978)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Array failure modes, relevant materials property changes, and primary degradation mechanisms are discussed as a prerequisite to identifying suitable measurement techniques and instruments. Candidate techniques and instruments are identified on the basis of extensive reviews of published and unpublished information. These methods are organized in six measurement categories - chemical, electrical, optical, thermal, mechanical, and other physicals. Using specified evaluation criteria, the most promising techniques and instruments for use in life prediction tests of arrays were selected.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: NASA-CR-157084 , DOE/JPL-954328-78/1
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 3
    facet.materialart.
    Unknown
    Thermophysical properties of plasma sprayed coatings (1973)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Thermophysical properties of plasma sprayed materials were determined for the following plasma sprayed materials: CaO - stabilized ZrO2, Y2O3 - stabilized ZerO2, Al2O3, HfO2 Mo, nichrome, NiAl, Mo-ZrO2, and MoAl2O3 mixtures. In all cases the thermal conductivity of the as-sprayed materials was found to be considerably lower than that of the bulk material. The flash-laser thermal diffusivity technique was used both for diffusivity determination of single-layer materials and to determine the thermal contact resistance at the interface of two-layer specimens.
    Keywords: MATERIALS, NONMETALLIC
    Type: NASA-CR-121144
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 4
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    Performance degradation mechanisms and modes in terrestrial photovoltaic arrays and technology for their diagnosis (1978)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Accelerated life-prediction test methodologies have been developed for the validation of a 20-year service life for low-cost photovoltaic arrays. Array failure modes, relevant materials property changes, and primary degradation mechanisms are discussed as a prerequisite to identifying suitable measurement techniques and instruments. Measurements must provide sufficient confidence to permit selection among alternative designs and materials and to stimulate widespread deployment of such arrays. Furthermore, the diversity of candidate materials and designs, and the variety of potential environmental stress combinations, degradation mechanisms and failure modes require that combinations of measurement techniques be identified which are suitable for the characterization of various encapsulation system-cell structure-environment combinations.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: Photovoltaic Specialists Conference; Jun 05, 1978 - Jun 08, 1978; Washington, DC
    Format: text
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    NASA TECHNICAL REPORTS
  • 5
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    Measurement requirements and techniques for degradation studies and lifetime prediction testing of photovoltaic modules (1978)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Tests of weathering and aging behavior are being developed to characterize the degradation and predict the lifetimes of low-cost photovoltaic arrays. Environmental factors which affect array performance include UV radiation, thermal energy, water, oxygen (generally involved in synergistic effects with UV radiation or high temperatures), physical stress, pollutants (oxides of nitrogen, sulfur dioxide and ozone), abrasives and dirt. A survey of photovoltaic array testing has shown the need to establish quantitative correlations between certain measurable properties (carbonyl formation, glass transition temperature, and molecular weight change) and modes of degradation and failure.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: Seminar on Testing Solar Energy Materials and Systems; May 22, 1978 - May 24, 1978; Gaithersburg, MD
    Format: text
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    NASA TECHNICAL REPORTS
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