Titlebook: Materials and Fluids Under Low Gravity; Proceedings of the I Lorenz Ratke,Hannes Walter,Berndt Feuerbacher Conference proceedings 1996 Spri

NORM

,A study of morphological stability during directional solidification of a Sn?Bi alloy in microgravistages. Wavelengths and segregation patterns of microstructures corresponding to well-defined distances to threshold are characterized by post mortem analyses. The experimental results are discussed within the frame of the Mullins and Sekerka‘s theory and 3D non linear calculations.

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New critical phenomena observed under weightlessness,new mechanism of heat transport, the “Piston effect”, has been discovered. This mechanism is due to the expansion of a conductive thermal boundary layer and leads to a “critical speeding up” instead of the usual “critical slowing-down”. In the presence of an external force (e.g. gravity) the boundar

jet-lag

Numerical solutions of thermoacoustic and buoyancy-driven transport in a near critical fluid,avier-Stokes equations of a van der Waals gas (CO.). The results have been focused on some striking behaviours compared to those obtained for normally compressible gases: i) heat equilibration is still achieved very fast under normal gravity conditions, as under zero-g conditions, by the Piston Effe

theta-waves

勤勉

領(lǐng)帶

VOC

,A study of morphological stability during directional solidification of a Sn?Bi alloy in micrograviition from a planar front to a destabilized front, is investigated through the in-situ measurement of the Seebeck voltage between the ends of a directionally solidified sample. This technique allows to precisely detect the instability threshold in steady state conditions as well as during transient

coagulation

Response of crystal growth experiments to time-dependent residual accelerations,be correlated with thrusted firings. The Seebeck voltage measurement is related to the response of the instantaneous average melt composition at the melt-solid interface. This allows a direct comparison of numerical simulations with the Seebeck signals obtained on USMP-1. The effects of such acceler

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Growth of 20 mm diameter GaAs crystals by the floating zone technique during the D-2 Spacelab Missicond German Spacelab Mission D2. The GaAs rods were sealed in silica ampoules which contained and integrated As-source to provide controlled stoichiometry conditions. The heating system consisted of a specially designed mirror furnace. The results show that stoichiometric material was achieved withi