Kevin Amaratunga

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Regularity is a fundamental and desirable property of wavelets and perfect reconstruction filter banks (PRFBs). Among others, it dictates the smoothness of the wavelet basis and the rate of decay of the wavelet coefficients. This paper considers how regularity of a desired degree can be structurally imposed onto biorthogonal filter banks (BOFBs) so that(More)
Paraunitary filterbanks (PUFBs) can be designed and implemented using either degree-one or order-one dyadic-based factorization. This work discusses how regularity of a desired degree is structurally imposed on such factorizations for any number of channels M /spl ges/ 2, without necessarily constraining the phase responses. The regular linear-phase PUFBs(More)
GIS applications have recently begun to emerge on the Internet. The management of three-dimensional geographic datasets in this distributed environment poses a particularly challenging problem, which highlights the need for a good data representation. This paper presents a new multiresolution data representation: the Wavelet Triangulated Irregular Network(More)
2 SUMMARY In this paper, we provide an introduction to wavelet representations for complex surfaces (surface wavelets), with the goal of demonstrating their potential for 3D scientific and engineering computing applications. Surface wavelets were originally developed for representing geometric objects in a multiresolution format in computer graphics. These(More)
This paper describes an algorithm for systematically finding a multiplierless approximation of transforms where VLSI-friendly binary coefficients of the form k/2<sup>n</sup> are employed in the approximation. Assuming the cost of binary shifters is negligible in hardware, the total number of binary adders required to approximate the transform is used as the(More)
In this paper we describe how wavelets may be used to solve partial di erential equations. These problems are currently solved by techniques such as nite di erences, nite elements and multigrid. The wavelet method, however, o ers several advantages over traditional methods. Wavelets have the ability to represent functions at di erent levels of resolution,(More)
In this paper, the lifting factorization and structural regularity of the lapped unimodular transforms (LUTs) are studied. The proposed M-channel lifting factorization is complete, is minimal in the McMillan sense, and has diagonal entries of unity. In addition to allowing for integer-to-integer mapping and guaranteeing perfect reconstruction even under(More)
We extend the method of lifting from M -channel paraunitary filter banks (PUFB) to M -channel unimodular filter banks. In particular, the lifting factorizations of Type-I and Type-II building blocks for the first-order unimodular matrices are presented, where the McMillan minimality is preserved. The proposed factorizations continue to have unity diagonal(More)
Two proteins specifically involved in methanol oxidation in the methylotrophic bacterium Methylobacterium extorquens have been modified by site-directed mutagenesis. Mutation of the proposed active site base (Asp303) to glutamate in methanol dehydrogenase (MDH) gave an active enzyme (D303E-MDH) with a greatly reduced affinity for substrate and with a lower(More)