Kevin Amaratunga

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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)
In this paper we describe how wavelets may be used to solve partial diierential equations. These problems are currently solved by techniques such as nite diierences, nite elements and multi-grid. The wavelet method, however, ooers several advantages over traditional methods. Wavelets have the ability to represent functions at diierent levels of resolution,(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)
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)
MxaJ is a protein of unknown function encoded by mxaJ in the mxaFJGI operon. We have constructed a mxaJ mutant of M. extorquens with a deletion which does not affect transcription of downstream genes. It contained cytochrome cL (MxaG), but neither subunit of methanol dehydrogenase (MxaF and MxaI). MxaJ is probably involved in processing this enzyme. We have(More)
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)
Digital aerial photography provides a useful starting point for computerized map generation. Features of interest can be extracted using a variety of image-processing techniques, which analyze the image for characteristics such as edges, texture, shape and color. In this work, we develop an automatic road detection system for use on high-resolution(More)
This paper presents a lifting-domain design of filter banks with a given McMillan degree. It is based on the M-channel lifting fac-torizations of the degree-0 and 1 building blocks I − 2uv † and I − uv † + z −1 uv † , with v † u = 1. Paraunitariness further requires u = v. The proposed lifting factorization has a unity diagonal scaling throughout, and(More)