Browsing by Author "CHANG, WT"

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CLUSTERING APPROACH TO GROUPING OBJECTS IN MESSAGE-PASSING SYSTEMS
(1995-10-01)
CHANG, WT
;
TSENG, CC
;
資訊工程學系
;
Department of Computer Science
Grouping related objects into processing nodes is one of the cost-effective solutions in distributed OOP. The authors propose a hierarchical clustering grouping strategy to minimize the cost of invocations on a given class hierarchy in a distributed manner.
FAST SURFACE INTERPOLATION USING MULTIRESOLUTION WAVELET TRANSFORM
(1993)
YAOU, MH
;
CHANG, WT
;
傳播研究所
;
Institute of Communication Studies
FAST SURFACE INTERPOLATION USING MULTIRESOLUTION WAVELET TRANSFORM
(1994-07-01)
YAOU, MH
;
CHANG, WT
;
電信工程研究所
;
Institute of Communications Engineering
Discrete formulation of the surface interpolation problem usually leads to a large sparse linear equation system. Due to the poor convergence condition of the equation system, the convergence rate of solving this problem with iterative method is very slow. To improve this condition, a multiresolution basis transfer scheme based on the wavelet transform is proposed. By applying the wavelet transform, the original interpolation basis is transformed into two sets of bases with larger supports while the admissible solution space remains unchanged. With this basis transfer, a new set of nodal variables results and an equivalent equation system with better convergence condition can be solved. The basis transfer can be easily implemented by using an QMF matrix pair associated with the chosen interpolation basis. The consequence of the basis transfer scheme can be regarded as a preconditioner to the subsequent iterative computation method. The effect of the transfer is that the interpolated surface is decomposed into its low-frequency and high-frequency portions in the frequency domain. It has been indicated that the convergence rate of the interpolated surface is dominated by the low-frequency portion. With this frequency domain decomposition, the low-frequency portion of the interpolated surface can be emphasized. As compared with other acceleration methods, this basis transfer scheme provides a more systematical approach for fast surface interpolation. The easy implementation and high flexibility of the proposed algorithm also make it applicable to various regularization problems.
HALF-BAND FILTER DESIGN WITH ODD-POLYNOMIAL CHEBYSHEV-APPROXIMATION
(1991-08-01)
CHANG, WT
;
LIN, MS
;
電信工程研究所
;
電信研究中心
;
Institute of Communications Engineering
An efficient method for the design of the half-band filter is described. Both the characteristics of the time response and the frequency response of the half-band filter are fully utilised to reduce the computation time and to increase the computation accuracy. The algorithm is based on the Chebyshev approximation criterion and uses only odd-symmetry polynomials for frequency interpolation to meet the required frequency response of the half-band filter.
IMAGE INTERPOLATION BY ANALOG CIRCUIT
(1992-04-23)
HSIEH, HC
;
CHANG, WT
;
電信工程研究所
;
Institute of Communications Engineering
An analogue computation circuit is proposed for image interpolation. This circuit is designed to maximise the smoothness of the interpolated data. With this circuit, high speed interpolation can be easily achieved.
INCREMENTAL MANEUVER ESTIMATION MODEL FOR TARGET TRACKING
(1992-04-01)
CHANG, WT
;
LIN, SA
;
電信工程研究所
;
電信研究中心
;
Institute of Communications Engineering
Target maneuver has long been a problem of tracking small targets with the Kalman filter. We describe an incremental model for maneuver detection and estimation for use in target tracking with the Kalman filter. The approach is similar to the multiple Kalman filter bank, but with a memory for the maneuver status for the track under consideration. The advantage of this approach is that the target acceleration can be more accurately estimated.
M-ARY WAVELET TRANSFORM AND FORMULATION FOR PERFECT RECONSTRUCTION IN M-BAND FILTER BANK
(1994-12-01)
YAOU, MH
;
CHANG, WT
;
交大名義發表
;
傳播研究所
;
National Chiao Tung University
The binary wavelet transform is generalized and extended to the M-ary biorthonormal case. The computational equivalence between the discrete wavelet analysis and the M-band multirate signal filtering is indicated. The equivalence allows the perfect reconstruction requirement in a filter bank to be investigated from the vector space decomposition/reconstruction in wavelet analysis. From the construction of the biorthonormal wavelet bases, the necessary and sufficient condition for the filters in a perfect reconstruction filter bank is formulated. Under this formulation, an additional optimization procedure is then used to model the frequency domain requirement in filter bank design.
MULTIRESOLUTION CODING FOR DIGITAL TRANSMISSION
(1993)
LIN, SW
;
CHANG, WT
;
電信工程研究所
;
Institute of Communications Engineering
Multiresolution interpolative DPCM for data compression
(1995)
HO, WJ
;
CHANG, WT
;
電信工程研究所
;
Institute of Communications Engineering
NONUNIFORM EMBEDDED QAM FOR VIDEO TRANSMISSION
(1994)
CHANG, WT
;
KUO, CC
;
電信工程研究所
;
Institute of Communications Engineering
VIRTUAL KNOT TECHNIQUE FOR CURVE-FITTING OF RAPIDLY VARYING DATA
(1994-02-01)
HSIEH, HC
;
CHANG, WT
;
電信工程研究所
;
Institute of Communications Engineering
Curve fitting with piecewise splines for rapidly varying data has been a difficult problem. Often, the curve exhibits unwanted ''wiggles'' around those data points whose locations change rapidly in comparison to their neighboring data points. Many methods were proposed to solve this problem using non-homogeneous tension spline or fairing process. In this paper, a new approach using the concept of virtual knots is presented. Since the occurrence of the problem is due to the inconsistency between the parametric spans of the knots and the geometric spans of the data points, a number of virtual knots are inserted into the original knot sequence such that the parametric spans are made more consistent with the geometric spans of the data. With this parametric adjustment, a regularization process is used to find the desired curve. Experimental results show that this technique is efficient to adjust the fairness of the desired curve. This technique can be applied to different spline spaces. In this paper, the usages of this technique in linear B-spline and cubic B-spline spaces are demonstrated.
WAVELET TRANSFORM IN SCATTERING DATA INTERPOLATION
(1993-10-14)
YAOU, MH
;
CHANG, WT
;
傳播研究所
;
Institute of Communication Studies
A fast algorithm for scattering data interpolation is presented. Based on the multiresolution wavelet transform, a preconditioning scheme is proposed to expedite the slow computation speed in the interpolation problem. By applying the wavelet transform before and after any conventional iterative solving method, fast data interpolation can be easily achieved.