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Free floating subsea robots are often subjected to complex hydrodynamic loads due to waves/currents and wakes from nearby structures. This makes control extremely difficult. Good hydrodynamics data might counteract this. This paper presents hydrodynamics data for two configurations undergoing various combinations of steady translation and approximately steady rotation. The two configurations are: a spherical body with a single fixed link arm and a two link arm without a body. For both configurations neural networks were found to provide a reasonable fit to the data. We believe that such fits could be used to improve control. 相似文献
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G. C. Capitani H. Leroux J. C. Doukhan S. Ríos M. Zhang E. K. H. Salje 《Physics and Chemistry of Minerals》2000,27(8):545-556
The nature of the amorphous regions and their recovery processes in two natural metamict zircon samples from Sri Lanka have
been studied by high resolution and analytical transmission electron microscopy. Samples untreated and annealed at different
temperatures were investigated. Nanoprobe analyses on untreated samples and samples annealed at 1000 K show that within experimental
uncertainties, no chemical segregation occurred. In samples annealed at higher temperatures (≥1100 K) recovery occurs in a
two-stage process and leads to different microstructures, which depended on the initial amount of metamictization. In highly
amorphized samples, recrystallization starts at 1200 K. Randomly oriented ZrO2 grains embedded in a silica-rich matrix are detected. At higher temperature (16 h at 1600 K), the assemblage transforms into
a polygonal texture of small zircon grains. Some untransformed zirconia grains and pockets of silica-rich glass are still
present, however. In partially metamict samples, recovery starts at 1100 K. The small surviving oriented zircon domains grow
at the expense of the surrounding amorphous material. At 1200 K, new zirconia grains nucleate with random orientations. After
1 h annealing at 1400 K, the zircon structure is restored and the microstructure coarse-grained. The proportion of crystalline
zirconia and silica-rich glass has dramatically decreased.
Received: 15 November 1999 / Accepted: 1 March 2000 相似文献
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