Longitudinal profiles of ephemeral streams in southeastern Arizona

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Transactions Briefs A Hybrid Radix-4/Radix-8 Low Power Signed Multiplier Architecture

Abstract—A hybrid radix-4/radix-8 architecture targeted for high bit, general purpose, digital multipliers is presented as a compromise between the high speed of a radix-4 multiplier architecture and the low power dissipation of a radix-8 multiplier architecture. In this hybrid radix-4/radix-8 multiplier architecture, the performance bottleneck of a radix-8 multiplier, the generation of three times the multiplicand for use in generating the radix-8 partial product, is performed in parallel with the reduction of the radix-4 partial products rather than serially, as in a radix-8 multiplier. This hybrid radix-4/radix-8 multiplier architecture requires 13 % less power for a 64 2 64-b multiplier, and results in only a 9 % increase in delay, as compared with a radix-4 implementation. When the voltage supply is scaled to equalize delay, the 64 2 64b hybrid multiplier dissipates less power than either the radix-4 or radix-8 multipliers. The hybrid radix-4/radix-8 architecture is therefore appropriate for those applications that must dissipate minimal power while operating at high speeds. Index Terms—Low power, multiplier, radix. I

Scale Dependency of Hydraulic Conductivity Measurements

The hydraulic conductivity of five stratigraphic units in a carbonate aquifer has been measured with slug, pressure, and pumping tests, and with two calibrated digital models. The effective test radii range from less than one to greater than 10,000 meters. On log‐log plots hydraulic conductivity increases approximately linearly with test radius to a range between 20 and 220 meters, but thereafter, it is constant with scale. The increase in magnitude of hydraulic conductivity is similar to scaling effects reported at seven additional sites in a variety of geologic media. Moreover, the increase in magnitude correlates with an increase in variance of log‐hydraulic conductivity measured at successively greater separation distances. The rate of increase in both parameters, and particularly the range, have characteristic values for different pore systems. The larger ranges are consistently present in units with greater secondary porosity. Therefore, scaling effects provide a qualitative measure of the relative importance of secondary and primary permeability, and they can potentially be used to distinguish the dominant type of pore system

Clustering Analysis Algorithms and Their Applications to Digital POSS-II Catalogs

. We report on the preliminary results of experiments using a Bayesian cluster method to cluster objects present in photographic images of the POSS-II. Our goal is to explore the power of unsupervised learning techniques to classify objects meaningfully, and perhaps to discover previously unrecognized object categories in digital sky surveys. Our primary finding is that the program we used, AutoClass, was able to form several sensible categories from a few simple attributes of the object images, separating the data into four recognizable and astronomically meaningful classes: stars, galaxies with bright central cores, galaxies without bright cores, and stars with a visible "fuzz" around them. Also, in an independent experiment we found out that the two types of galaxies have distinct color distributions (the more concentrated class being redder, as indeed expected if they are predominantly early Hubble types), although no color information was given to AutoClass. This illustrates the p..