Browsing by Author "Fotheringham, Ulrich"

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    Active thermal conductivity of hot glass
    (Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 1994) Fotheringham, Ulrich; Lentes, Frank-Thomas
    For (semi)transparent glass, it is suggested to distinguish between an active and a passive thermal conductivity. Essentially, the latter is attached to the heat transfer through long-range photons most of which are both emitted and absorbed outside the glass volume, the former to the heat transfer through phonons and short-range photons which have an intense energy exchange with the glass. As the temperature distribution in the glass volume can be influenced only by the heat exchange in which the glass is actively involved, it is determined by the active thermal conductivity. The sum of the active and the passive thermal conductivity, which is identical to the so-called apparent thermal conductivity, indicates the overall heat flux through the glass. Like the apparent thermal conductivity, the active thermal conductivity can be obtained from the prototype of thermal conductivity measurements where the heat flux through a sample between two heat reservoirs of different temperatures is measured. The apparent thermal conductivity follows from the usual reduction o f the measurement data, the active thermal conductivity is derived via a differentation rule. Comparing the calculation and the measurement of the temperature inside a cooling block of glass, this differentiation rule is verified.
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    Atomistic simulation of glasses - Strategic considerations and review of selective results
    (Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 2005) Fotheringham, Ulrich; Binder, Kurt; Horbach, Jürgen; Kob, Walter
    Within the seope of a ten year cooperation between SCHOTT AG and Mainz University, important contributions to the atomistic simulation of multicomponent glasses have been developed. They have made the state of the art come closer to the visionary goal of determining the properties of unknown glasses a priori by theoretical means.
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    New generation of dispersion-flattened single-mode fibers
    (Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 1989) Fotheringham, Ulrich
    For the first time a dispersion-flattened single-mode fiber has been manufactured which has chromatic dispersion zeros both at wavelengths of 1.3 and 1.55 μm. Present standard-type single-mode fibers are designed for either of these wavelengths and the new fiber is compatible to both of them. In contrast to other fiber refractive index profile optimization routines a new theory for continuous profiles has been used for the fiber design. Thus, interesting and important modifications of the conventional structures of dispersion-flattened single-mode fibers have been developed. For the profile realization a method is required which allows for the continuous variation of the refractive index over the fiber cross section. With the plasma impulse chemical vapor deposition a satisfactory reproduction of the theoretical proposals is possible. Various fibers have been manufactured which showed exactly the intended chromatic dispersion. These fibers were called CP2 (compatible, continuous profile).