Browsing by Author "Hsiao, AT"

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A dual-snake model of high penetrability for ultrasound image boundary extraction
(2001-12-01)
Chen, CM
;
Lu, HHS
;
Hsiao, AT
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統計學研究所
;
Institute of Statistics
Most deformable models require the initial contour to be placed close to the boundary of the object of interest for boundary extraction of ultrasound (US) images, which is impractical in many clinical applications. To allow a distant initial contour, a new dual-snake model promising high penetrability through the interference of the noises is proposed in this paper. The proposed dual-snake model features a new far-reaching external force, called the discrete gradient flow, a connected component-weighted image force, and an effective stability evaluation of two underlying snakes. The experimental results show that, with a distant initial contour, the mean distance from the derived boundary to the desired boundary is less than 1.4 pixels, and most snake elements are within 2.7 pixels of the desired boundaries for the synthetic images with CNR greater than or equal to 1. For the clinical US images, the mean distance is less than 1.9 pixels, and most snake elements are within 3 pixels of the desired boundaries. (E-mail: chung@lotus.mc.ntu.edu.tw) (C) 2002 World Federation for Ultrasound in Medicine Biology.
Miniaturized 3 GHz cross-coupled planar microwave filters
(2004-03-01)
Zeng, HK
;
Hsiao, AT
;
Hsu, WH
;
Wu, SW
;
Lin, JY
Cross-coupled planar microwave filters were fabricated using YB2Cu3O7-delta superconducting thin films deposited on both sides of a LaAlO3 single crystal substrate by pulsed laser deposition. The hairpin resonator geometry allows one to miniaturize the 3-GHz filters by compacting the entire filter onto a substrate with dimensions 0.5 cm x 1 cm. By adjusting the relative spacing among the resonators to establish adequate couplings, filters with very sharp rejection skirt and extremely small insertion loss in passband were obtained.