Based on the interpretations of three seismic profiles and one wide-angle seismic profile across the Northwest Sub-basin, South China Sea, stratigraphic sequences, deformation characteristics and an extension model for this sub-basin have been worked out. Three tectonic-stratigraphic units are determined. Detailed analyses of extension show that the event occurred mainly during the Paleogene and resulted in the formation of half-grabens or grabens distributed symmetrically around the spreading center. Sediments are characterized by chaotic and discontinuous reflectors, indicating clastic sediments. Farther to the southwest, the sub-basin features mainly continental rifting instead of sea-floor spreading. The rifting would have been controlled by the shape of the massif and developed just along the northern edge of the Zhongsha-Xisha Block, rather than joined the Xisha Trough. After 25 Ma, a southward ridge jump triggered the opening of the Southwest Sub-basin. The NW-directed stress caused by the sea-floor spreading of the Northwest Sub-basin may have prevented the continuous opening of the sub-basin. After that the Northwest Sub-basin experienced thermal cooling and exhibited broad subsidence. The deep crustal structure shown by the velocity model from a wide-angle seismic profile is also symmetrical * Corresponding author. Tel./fax: þ86 571 81963137, þ86 13588039531 (cellphone).
The use of recyclable forms of sulfur will exclude the risk of sediment reacidification and reduce the cost of bioleaching process. Three different forms of sulfur (namely sulfur powder, prills and pieces) were used to examine the utilization and recycle of sulfur, used as energy substrate for sulfur-oxidizing bacteria (SOB) in the bioleaching of heavy metal-contaminated sediments. The results showed that despite their relatively smaller surface areas, the efficiency of metal bioleaching with sulfur prills and pieces were comparable to that with sulfur powder. After 13 days of bioleaching, 71-74% of Zn, 58-62% of Cu, and 22-31% of Cr could be leached from the sediments, respectively. During bioleaching, most of the oxidizable and reducible forms of metals were transformed to acid soluble, posing a favorable condition for final metals removal. Sulfur recycling experiments showed that the recovered sulfur prills and pieces were as the same effective in pH reduction as fresh sulfur, revealing the feasibility of eventual reuse of the recycled sulfur in the bioleaching process. Further studies are required to testify the performance of these recyclable forms of sulfur in future large-scale bioleaching reactor.
Face recognition is one of the most important part of biometrical recognition. 2-Dimensional Principal Component Analysis (2DPCA)is a classic method in face recognition, which is proposed to reduce the computational cost of the standard Principal Component Analysis (PCA) algorithm, but the performance of 2-Dimensional Principal Component Analysis in reducing computational complexity and recognition rate is not satisfying. This paper mainly focuses on the feature extraction method of adaptively weighted Block 2-Dimensional Principal Component Analysis. The block methods divide a large picture into several smaller sub-blocks to get the local discrimination information and reduce the computational complexity. Then, a weighted Euclidean distance classifying algorithm is proposed to extract features of face images, and the Euclidean distance classifier is used for classifying. The experiments show that the Adaptively Weighted Block 2-Dimensional Principal Component Analysis method has better performance than standard 2-Dimensional Principal Component Analysis.
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