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  • 1
    Electronic Resource
    Electronic Resource
    Simultaneous two-line operation of a CW CO laser with arbitrary choice of laser transitions (1988)
    Springer
    Applied physics 45 (1988), S. 13-16 
    Details
    ISSN: 1432-0649
    Keywords: 42.60.Da ; 33.80.B
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract An experimental scheme is discussed, by which we can operate a CO laser at two individually selectable lines from the same gain tube. There are virtually no restrictions on the wavelength separation of the two lines within the manifold of the available lasing transitions. Experimental verifications of this scheme are described and the mutual influence of the simultaneous laser operation is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00692334
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    A new technique for state-to-state studies of unimolecular reactions (1988)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 89 (1988), S. 4448-4450 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: A double-resonance technique which combines infrared excitation of a fundamental vibration of a light atom oscillator with vibrational overtone excitation of that same oscillator selectively prepares molecules in individual quasibound vibrational–rotational states at energies above their dissociation threshold. A third laser probes individual states of the product fragments via laser induced fluorescence. We present our initial results applying this technique to study the 6νOH vibrational overtone spectroscopy and unimolecular dissociation dynamics of hydrogen peroxide (HOOH). The double-resonance approach simplifies the congested vibrational overtone spectrum of HOOH, and the linewidth of resolved features places a lower limit on the lifetime of approximately 7 ps.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.454782
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Arteether, a new antimalarial drug: synthesis and antimalarial properties (1988)
    s.l. : American Chemical Society
    Journal of medicinal chemistry 31 (1988), S. 645-650 
    Details
    ISSN: 1520-4804
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/jm00398a026
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    A pseudo-time integral method for non-isothermal viscoelastic flows and its application to extrusion simulation (1987)
    Springer
    Rheologica acta 26 (1987), S. 499-507 
    Details
    ISSN: 1435-1528
    Keywords: Time-temperature superposition ; extrusion swell ; Péclet number
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract A pseudo-time integral scheme based on a finite streamline element method is developed to combine variable temperature with viscoelasticity. A specific KBKZ integral model for isothermal flow is transformed to its non-isothermal version by introducing a pseudo-time and applying the Morland-Lee hypothesis. The coupling between momentum and energy equations is through the time-temperature shifting factor by which the pseudo-time is defined. The observer time and the pseudo-time are simultaneously calculated when tracing the strain history for the stress calculation in a non-homogeneous temperature field. Using this scheme, a full non-isothermal numerical simulation of some IUPAC extrusion experiments is carried out. Results show that while the temperature distribution near the die exit plane is an important factor controlling extrudate swell, either self-heating inside the die tube or external cooling on the free surface dominantly determines the temperature distribution near the die exit when the wall temperature is kept constant, depending on whether the Péclet number is large or small. The hot layer effect predicted by the inelastic swell mechanism is confirmed and well illustrated by the computation. Calculations with reasonable thermal boundary conditions further convince us that the isothermal assumption in our earlier numerical simulation is a good approximation in this particular case.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01333733
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  • 5
    Electronic Resource
    Electronic Resource
    Finite element simulation of long and short circular die extrusion experiments using integral models (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 25 (1988), S. 9-22 
    Details
    ISSN: 0029-5981
    Keywords: Streamline Elements ; KBKZ Model ; LDPE Extrusion ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: A finite streamline element method for use with integral type constitutive equations in viscoelastic flow simulation, including thermal effects, is presented and some new results using this method in modelling the IUPAC extrusion experiments for low-density polyethylene (LDPE), involving both long and short circular dies, are reported and discussed. It will be shown that the special streamline-based elements provide a convenient way of particle tracking and strain tensor calculation. The extrusion calculation when using a relatively realistic KBKZ type integral model with multiple relaxation times is stable, and practically important Weissenberg numbers and swelling ratios have been reached without difficulty. The agreement with experimental swelling ratios is on the whole satisfactory. In order to make the model a good fit to the Trouton viscosity experimental data of the LDPE sample, a spectrum of elongational parameters has been introduced. The second normal stress term has also been added to the integral model to examine its effect on extrusion swelling. The non-isothermal effects and the possibility of a wall slip near the die exit at high apparent shear rates are also discussed.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620250104
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  • 6
    Electronic Resource
    Electronic Resource
    A computer study of film blowing (1985)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 25 (1985), S. 620-629 
    Details
    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 extends Petrie's work on film-blowing to cover viscoelastic non-isothermal flow for both the convected Maxwell and the Leonov models. Good agreement with experimental data is shown for the former. The calculations are highly unstable, however, and it is difficult to obtain convergence with arbitrary values of the film-blowing parameters. The general effect of viscoelasticity is to stiffen the film and restrain the increase in bubble diameter. There is some difference between bubble shapes generated using the Maxwell and Leonov constitutive models but the temperature variation of properties is seen as the dominant effect, The Leonov model tends not to be stiff enough in its response to the present flow, which is purely extensional and good agreement with experiment was not obtained. For the Maxwell model the relevant mean relaxation time must be used for good agreement between experiment and calculation.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760251008
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