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  • ASTROPHYSICS  (119)
  • Chemical Engineering  (90)
  • STRUCTURAL MECHANICS
  • 1980-1984  (203)
  • 1970-1974
  • 1965-1969
  • 1960-1964  (24)
  • 1981  (203)
  • 1961  (24)
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  • 1980-1984  (203)
  • 1970-1974
  • 1965-1969
  • 1960-1964  (24)
Year
  • 1
    Publication Date: 2019-06-28
    Description: On five occasions in 1977 and 1978, Cygnus X-1 was observed using the low-energy detectors of the UCSD/MIT Hard X-ray and Low-Energy Gamma Ray experiment on the HEAO 1 satellite. Rapid (times between 0.08 and 1000 sec) variability was found in the 10-140 keV band. The power spectrum was white for frequencies between 0.001 and 0.05 Hz and was proportional to the inverse of the frequency for frequencies between 0.05 and 3 Hz, indicating correlations on all time scales less than approximately 20 s. The shape of the energy spectrum was correlated with intensity; it was harder at higher intensity. If the emission is produced by Comptonization of a soft photon flux in a hot cloud, the heating of the cloud cannot be constant; it must vary on time scales up to approximately 20 s. A variable accretion rate could cause the observed effects.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 246
    Format: text
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  • 2
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 21 (1981), S. 39-46 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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: Thermoplastic interpenetrating polymer networks, IPN's, are defined as combinations of two physically crosslinked polymers. A styrene-b-ethylene-co-butylene-b-styrene (SEBS) triblock elastomer was combined with an ionomer prepared from a random copolymer of styrene, methacrylic acid, and isoprene (90/10/1 by volume), and subsequently neutralized. Two subclasses of the thermoplastic IPN's were identified. A sequential polymerization method yielded the chemically blended thermoplastic IPN's (CBT IPN's). Melt blending of the separately synthesized polymers produced the mechanically blended thermoplastic IPN's (MBT IPN's). Stress-strain and Rheovibron characterization revealed that the CBT IPN's exhibited greater tensile strength and higher elongation at break, but lower moduli than the MBT IPN materials of the same overall composition. Analysis of moduli data with the theories of Takayanagi, Davies, Budiansky, and Kerner disclosed more equal dual phase continuity for the MBT IPN's than the CBT IPN's at each composition. The low modulus of the more rubbery CBT IPN compositions was attributed to a decrease in the effective chain end-to-end distance between crosslinks in the elastomeric (EB) center block, brought about by the synthetic method.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 21 (1981), S. 151-154 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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: Recovery experiments above Tg have been performed on glass bead and short glass fiber polystyrene composite sheets obtained from extrusion and subsequent hot drawing. A shift procedure has been applied to recoil data using the Williams-Landel-Ferry (WLF) equation with the same values of C1 and C2 used for unfilled polystyrene. The data reported show that an improvement of the dimensional stability of a drawn thermoplastic material can be obtained by adding very low volume percentage of fibers. Moreover, all the recoil data have been reduced to a unique generalized master curve which takes into account the draw ratio, the filler content, and geometry, using a fractional distance from equilibrium as a measure of the recovery. These results indicate that the presence of the filler does not affect the recoil kinetics of the polymeric matrix.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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: A spectrum of newly synthesized polyamides have been characterized with the intent of elucidating crystalline and possible liquid crystalline behavior. The different polymers contained various rotatable linkages in the main chain as well as substituent methyl groups in some cases. These were deemed as important variables for controlling the propensity to form ordered morphologies in these polymers. Methods of characterization included: X-ray diffraction analysis, differential scanning calorimetry, and optical birefringence.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 21 (1981), S. 755-767 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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: This paper describes the results of a theoretical and experimental study on the rheology of thermoplastics subjected to mechanical effects at extrusion conditions. The spiral flow of non-Newtonian systems has been studied and quantitative relationships obtained for its description, which are suitable for engineering. The effect of rotational low-frequency large-amplitude vibrations on the flow of melts in the extruder's head of simple (circular) and complex cross sections has been studied and an analysis provided for flow with small-amplitude high-frequency (ultrasonic) superimposed vibrations. The energy efficiency of cyclic deformation upon extrusion has been estimated. The investigation has provided recommendations for the application of complex shear as a method of directed action on the relaxation and, hence, rheological characteristics of polymers. This opens up new possibilities for the intensification of the extrusion processes and compositions based on thermoplastics.
    Additional Material: 19 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 27 (1981), S. 877-878 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 7 (1961), S. 551-558 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The effect of design and operational variables on the performance of one type of hydrogen-oxygen ion exchange membrane fuel cell has been studied. Only the results of cells based on a phenolsulfonic acid formaldehyde type of ion exchange membrane containing one type of reinforcement are described. Platinum, palladium, iridium, and rhodium are adequate electrode materials for room-temperature operation. Performance of cells with platinum gauze current collectors bonded to the cell surfaces was only slightly better than that with external contacts about 1 cm. apart.Open circuit voltages range from 0.9 to 1.1 v. (theoretical 1.23) depending on the catalyst. The typical current at 0.5 v. is 30 ma./sq. cm. Better cells have delivered 80 ma./sq. cm. at 0.5 v. Life tests indicate that these cells can be expected to deliver a minimum of about 40 amp.-hr./sq. cm., when operated in the load range 8.5 to 230 ohm sq. cm., before failure of the electrolyte owing to pinhole formation. Current efficiency is very nearly 100%. Cell performance vs. temperature in the range 0° to 85°C. shows a maximum at about 55°C.
    Additional Material: 24 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 7 (1961), S. 663-665 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In predicting interfacial area in liquid-liquid systems there are several published reports which give different results. Differences in methods of measurement of interfacial area and impeller design and location account for some of these discrepancies.For one pair of liquids, 40 parts by volume of ethylhexanol and 60 parts water, it was found that over wide ranges of impeller size to tank size ratio (0.27 to 0.67) that equal power per unit volume gave equal interfacial area per unit volume.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Brookfield, Conn. : Wiley-Blackwell
    Polymer Composites 2 (1981), S. 29-35 
    ISSN: 0272-8397
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: The mechanical behavior of epoxy, hydroxyethymetherylate and polystyrene composites containing various percentages of glass microspheres was investigated over a wide range of temperature. The effect of filler concentration of the ductile-brittle transition and on the glass-transition temperature of the composites is reported. The utility of various predictive models for the effect of filler concentration on mechanical properties is assessed.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Brookfield, Conn. : Wiley-Blackwell
    Polymer Composites 2 (1981), S. 116-120 
    ISSN: 0272-8397
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: The viscoelastic behavior of epoxy composites containing various percentage of glass microspheres and random short glass fibers was investigated over a wide range of temperatures. The effect of the second phase is to increase the relaxation moduli of the system and to shift the time dependency to higher times. All the data were shifted to a single master curve at a reference temperature by using independent shift factors that were a function of either temperature or filler content.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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