This paper presents a novel region-based video coding algorithm for very low bit-rate transmission. A huge amount of region shape information in a conventional region-based coding does not need to be transmitted in the new approach, because it can be synchronously obtained from a reconstructed picture in both encoder and decoder by image segmentation. Segmented region updating, which can obtain appropriate regions for motion compensated prediction, and a new bit assignment algorithm in prediction error coding are also developed. Computer simulations are carried out to evaluate the coding efficiency at 9.6 kbls. The result indicates that the objective and subjective qualities for decoded pictures are improved compared to those for the conventional block-based method. This algorithm is sigdicantly effective for mobile communication.

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The corrosion behaviour of a carbon steel weld joint under anaerobic conditions was investigated to estimate the long term integrity of the carbon steel overpack. The welded specimens in this study were prepared using three different welding methods: gas tungsten arc welding, gas metal arc welding and electron beam welding. General corrosion was observed for each immersion specimen, and the corrosion rate at the weld joint was the same as or less than that of the base metal. The concentration of hydrogen that absorbed during immersion testing was ,2?48610 25 mol kg[Fe] 21 (0?05 ppm) after 3 years, a value regarded as having little influence on hydrogen embrittlement. The susceptibility to hydrogen embrittlement was the highest in the base metal, suggesting that there was little adverse effect on the weld joint from welding. The welded carbon steel overpack is assumed to maintain its resistance to corrosion as a disposal container for the expected lifetime under anaerobic underground conditions.

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