Browsing by Author "Wu, SW"

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B*-trees: A new representation for non-slicing floorplans
(2000)
Chang, YC
;
Chang, YW
;
Wu, GM
;
Wu, SW
;
資訊工程學系
We present in this paper an efficient, flexible, and effective data structure, B*-trees, for non-slicing floorplans. B*-trees are based on ordered binary trees and the admissible placement presented in [1]. Inheriting from the nice properties of ordered binary trees, B*-trees are very easy for implementation and can perform the respective primitive tree operations search, insertion, and deletion in only O(1), O(1), and O(n) least O(n) time for each of these operations, where n is the number of modules. The correspondence between an admissible placement and its induced B*-tree is 1-to-1 (i.e., no redundancy); further, the transformation between them takes only linear time. Unlike other representations for non-slicing floorplans that need to construct constraint graphs for cost evaluation, in particular, the evaluation can be performed on B*-trees and their corresponding placements directly and incrementally. We further show the flexibility of B*-trees by exploring how to handle rotated, pre-placed, soft, and rectilinear modules. Experimental results on MCNC benchmarks show that the B*-tree representation runs about 4.5 times faster, consumes about 60% less memory, and results in smaller silicon area than the O-tree one [1]. We also develop a B*-tree based simulated annealing scheme for floorplan design; the scheme achieves near optimum area utilization even for rectilinear modules.
Electronic transport in insulating AlPdRe quasicrystals
(2004-02-18)
Rosenbaum, R
;
Murphy, T
;
Brandt, B
;
Wang, CR
;
Zhong, YL
Resistivity and magnetoresistance measurements have been performed on insulating icosahedral AlPdRe quasicrystal (QC) bar samples. At temperatures in the range 300 K greater than or equal to T greater than or equal to 50 K, the resistivities follow a simple inverse temperature law: rho(T) rho(0)/T(1.0+/-0.1). Below 1 K, the resistivity of a weakly insulating sample exhibited a simple inverse temperature law where rho(T) = rho0/T-0.33 and not an activated variable-range hopping (VRH) law. Strongly insulating samples exhibit saturation of their resistivities to finite values as T --> 0 K. These saturation resistivity values are believed to arise from the presence of a second metallic phase located within the quasicrystal's structure. By extrapolating the measured resistivities at 22 mK to absolute zero, the saturation conductivity values were estimated at T = 0 K and subtracted from the conductivity data points. These 'corrected' data, corresponding only to the QC phase, were found to follow activated VRH laws, having hopping exponents y that vary in the range 0.18 less than or equal to y less than or equal to 0.43. The activated VRH behaviours are observed only below 1 K. The magnetoresistances (MRs) of these samples are also anomalous. The MRs can be explained by including contributions from both the saturation conductivity values and from the QC MR ratios, estimated using the wavefunction shrinkage model.
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.