24 research outputs found
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THE EFFECT OF TRANSIENTS AND LONGER TIME ANNEALS ON IRRADIATED URANIUM- ZIRCONIUM ALLOYS
Small pieces of Zircaloy-clad 7 and 8 wt. % uranium-zirconium alloys irradiated from 0.4 to 1.5 at. % burnup of the total core atoms in the MTR were heat-treated at temperatures between 510 and 980 C for periods of time from 1 sec to 500 hr. The resulting changes in density, electrical resistiviiy, and microstructure were observed. Tbe core volume changes were found to be a function both of temperature and time at temperature for a given burnup. A decrease in the swelling rate with time was observed. Thus, at 620 C about 40% of the core volume change after 300 hr (37%) occurred in the first 6 hr. At lower temperatures, more time was required for an equivalent fractional volume change. Metallographic changes and gas bubble formation at phase boundaries were observed optically at temperatures as low as 510 C in high burnup material. Bubbles were also observed in the electron microscope. The changes observed appear to be due to the growth of inert gas bubbles formed in the epsilon phase of uranium-zirconium alloy and to a transformation occurring in the delta phase. The effect of irradiation temperature and flux on the nucleation and growth of the gas bubbles is discussed. (auth
Enhanced osmotic tolerance of Koala spermatozoa following treatment with the cytoskeletal disrupting agent, cytochalasin D
The morphology and life-cycle of Trichobilharzia parocellata (Johnston & Simpson, 1939) Islam & Copeman, 1980 from the visceral blood vessels of Australian anatids
Gradient Art: Creation and Vectorization
There are two different categories of methods for producing vector gradients. One is mainly interested in converting existing photographs into dense vector representations. By vector it is meant that one can zoom infinitely inside images, and that control values do not have to lie onto a grid but must represent subtle color gradients found in input images. The other category is tailored to the creation of images from scratch, using a sparse set of vector primitives. In this case, we still have the infinite zoom property, but also an advanced model of how space should be filled in-between primitives, since there is no input photograph to rely on. These two categories are actually extreme cases, and seem to exclude each other: a dense representation is difficult to manipulate, especially when one wants to modify topology; a sparse representation is hardly adapted to photo vectorization, especially in the presence of texture. Very few methods lie in the middle, and the ones that do require user assistance. The challenge is worth the effort though: it would make converting an image into vector primitives easily amenable to stylization