Let G be an additive finite abelian group with exponent exp(G). Let S = g1 · . . . · gl be a sequence over G and k(S) = ord(g1)+· · ·+ord(gl) be its cross number. Let η(G) (resp. t(G)) be the smallest integer t such that every sequence of t elements (repetition allowed) from G contains a non-empty zero-sum subsequence T of length |T | ≤ exp(G) (resp. k(T ) ≤ 1). It is easy to see that t(G) ≥ η(...

Classification of blocks of subband samples according to their energy and variable bit allocation within the subsequent classes has demonstrated considerable gains in coding efficiency. The gains due to classification increase as smaller blocks are used; however, this increases the overheads for transmitting the classification information. In this paper, a quadtree based method is proposed. Thi...

The use of subband coding on image data is discussed. An overviev~ of siibbai~d coding is given. Advantages of subbanding for browsing and progressive resol~itiori ar-e presented. Implementations for lossless and lossy coding are discussed. Algorithn~ considerations and simple implementations of subband systems are given.

In many industrialized areas, the highest concentration of particulate matter, as a major concern on public health, is being felt worldwide problem. Since the air pollution assessment and its evaluation with considering spatial dispersion analysis because of various factors are complex, in this paper, GIS-based modeling approach was utilized to zoning PM2.5 dispersion over Tehran, du...