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  • Polymer and Materials Science  (3)
  • SPACE RADIATION  (3)
  • FEM  (1)
  • 1985-1989  (7)
  • 1
    Electronic Resource
    Electronic Resource
    A constitutive equation for creep in polymer concretes and their resin binders (1988)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 36 (1988), S. 353-364 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: We present here a method for superposing creep measurements on polymer concrete (PC), taken at different temperatures, imposed stresses, and resin contents, onto master curves, which describe the respective responses of various PC systems and their resin binders, to compressive, tensile, and flexural loads. This treatment is extended to systems reinforced with chopped glass fiber and montmorillonite (MMT). The general applicability of this superposition is tested with creep measurements by other investigators under tensile, compressive, and flexural loads. The results make it possible to predict the long-term creep behavior of unfilled as well as reinforced glassy polymer systems at different temperatures and load conditions from limited, short-term data. Success of the multiple superposition suggests a generalized constitutive equation, which describes the creep compliance of these systems as a product of separable functions of each parameter in the form of shift factors for temperature (αT), stress (ασ), resin content (αυ), fiber reinforcement (αF), and MMT reinforcement (αM): J(PC) = JrαTασαυαFαMtm, where Jr is an appropriately chosen reference creep compliance. The time exponent m does not depend on the chemical nature of the polymer matrix.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1988.070360208
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Rheological behavior of thermotropic flexible main-chain polyesters based on 4,4′-dioxy-2,2′-dimethyl azoxybenzene mesogens. I. Oscillatory shear behavior (1986)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 24 (1986), S. 27-38 
    Details
    ISSN: 0887-6266
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The rheological properties of fractionated thermotropic nematic polyesters 4,4′-dioxy-2,2′-dimethyl azoxybenzenenonanediyl (n = 7) (AZA-9) and dodecanediyl (n = 10) (DDA-9) have been determined under oscillatory shear in the nematic and isotropic phase. A markedly more pronounced shear thinning characterizes the polydisperse DDA-9 polymer as compared to the fractionated polymer in the nematic state. This difference becomes less pronounced in the isotropic phase. In all cases, the elastic compliance J′ in the isotropic state is much lower than in the nematic state. The values of relaxation time λ, although lower in the isotropic state, are not very different in the nematic state. The loss tangent tan δ is significantly higher in the isotropic phase for lower molecular weights. For molecular weights of 13,000 and above, this difference becomes smaller and shifts to lower angular frequencies. For AZA-9 and DDA-9, ηω*→0 the limit of the dynamic viscosity can be represented by η* = Mna with a value of α similar for both phases and approximately equal to 4.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1986.180240104
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  • 3
    Electronic Resource
    Electronic Resource
    Enthalpy relaxation of filled copolymers (1985)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 30 (1985), S. 2315-2320 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Excess enthalpy following annealing at various periods of time at Tg -10°C was measured by differential scanning calorimetry of electrophotographic toners, copolymers of styrene and butyl methacrylate containing carbon black. An approximate equilibrium enthalpy relaxation after annealing the pure copolymers for one month was 3.30 kJ/kg for a copolymer with 66.5% styrene and 2.72 kJ/kg for a copolymer containing 49.8% styrene. The rate of enthalpy relaxation was reduced by increasing the styrene content of the pure copolymer. The incorporation of a carbon black with high surface area reduces the rate of enthalpy relaxation, increasing in effectiveness with butyl methacrylate concentration.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1985.070300604
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  • 4
    Electronic Resource
    Electronic Resource
    Laminar flow and heat transfer over a two-dimensional triangular step (1989)
    Chichester : Wiley-Blackwell
    International Journal for Numerical Methods in Fluids 9 (1989), S. 1165-1177 
    Details
    ISSN: 0271-2091
    Keywords: Laminar flow ; Triangular step ; FEM ; Velocity correction ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: The velocity correction algorithm is used in the finite element method to solve forced convection problems between parallel plates with a triangular step, for Reynolds numbers up to 1000. Equal-order interpolation functions for velocity, pressure and temperature are used. The solutions show a smooth variation of pressure. The streamfunction, isotherms, isobars and velocity profiles are presented for a typical Reynolds number of 500. The skin friction and heat transfer results are presented for Reynolds numbers up to 1000.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/fld.1650090909
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  • 5
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    Diurnal variation of galactic cosmic ray intensity on quiet days (1985)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A detailed study of the diurnal variation on long term basis was performed on geomagnetically quiet days using the experimental data of the cosmic ray intensity from the worldwide neutron monitoring stations. During the period when the polarity of the solar magnetic field in the Northern Hemisphere of the sun is negative the phase and amplitude of the diurnal anisotropy on quiet days was observed to remain almost constant. When the polarity of solar magnetic field in the Northern Hemisphere changes from negative to positive, a shift in the phase of the diurnal anisotropy on quiet days towards earlier hours is observed and the shift is found to be maximum during minimum solar activity periods 1953-54 and 1975-76. When the polarity of solar magnetic field changes from positive to negative in the Northern Hemisphere of the Sun the phase of the diurnal anisotropy on quiet days recovers to its usual direction of corotational anisotropy and is observed to remain almost constant till the polarity of the solar magnetic field does not change.
    Keywords: SPACE RADIATION
    Type: SH-4.5-11 , 19th Intern. Cosmic Ray Conf - Vol. 5; p 126-129; NASA-CP-2376-VOL-5
    Format: application/pdf
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  • 6
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    Study of spectral exponent on quiet and disturbed days (1985)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The spectral exponents of the diurnal and semidiurnal anisotropies are studied on quiet and disturbed days for a period from 1964 to 75. It has been observed for the diurnal anisotropy that the spectral exponent for quiet days is 0.0 from 1964 to 70, however during 1971 and onwards its value is found different from zero and is -0.4; for disturbed days the spectral exponent is observed to be 0.0 from 1964 to 75 with an exception of the year 1966. Further, it has been observed for the semi-diurnal anisotropy that the best value for the spectral exponent on quiet days being + 0.6 from 1964 to 74; however on disturbed days the value of spectral exponent is sometimes negative or positive but different from zero. It was derived from the present investigation that superimposed on the corotational anisotropy, expected from a balance between outward radial convection and inward field aligned diffusion, there is an additional component operating during the period under consideration.
    Keywords: SPACE RADIATION
    Type: SH-4.5-10 , NASA. Goddard Space Flight Center 19th Intern. Cosmic Ray Conf., Vol. 5; p 125
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  • 7
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    Comparative study of the phase of diurnal anisotropy on quiet and disturbed days on a long term basis up to recent period (1985)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The data from the world wide grid of neutron monitoring stations was analyzed for a comparative study of the phase of diurnal anisotropy on quiet and disturbed days on a long term basis up to recent period. It has been observed that the phase of the diurnal anisotropy on disturbed days where the value of the Ap-index is higher, is found to shift towards earlier hours in comparison to the phase of the diurnal anisotropy on quiet days where the value of Ap-index is lower on all the stations from 1965 to 71. Such a trend is not observable for the later period. This affect is found to be more pronounced on equatorial stations, in particular, in comparison to high latitude stations. It was derived from these observational facts that the relationship between Ap-index and the phase of the diurnal anisotropy is not invariant throughout the period of consideration. Furthermore, the exact cause of such a drastic change is not known, but it demonstrates very clearly that the interplanetary conditions which are responsible for both, diurnal anisotropy of cosmic ray intensity and the geomagnetic Ap-index variation, have drastically changed during the period 1971 and onwards.
    Keywords: SPACE RADIATION
    Type: SH-4.5-9 , NASA. Goddard Space Flight Center 19th Intern. Cosmic Ray Conf., Vol. 5; p 124
    Format: application/pdf
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