Thermal design issues and performance of microcalorimeter arrays at sub-Kelvin temperatures

We have produced 5/spl times/5 pixel arrays of microcalorimeters using bulk micromachining. Analysis of our data provides the thermal conductivity parameters of Si/sub x/N/sub y/ 1 /spl mu/m thick membranes at 100 mK. Moreover we find that the thermal transport at 100 mK in Si beams, with dimensions 1.25 mm /spl times/ 0.35mm /spl times/ 35/spl mu/m (length /spl times/ height /spl times/ width) is dominated by ballistic phonons with a mean free path of 110 /spl mu/m. These thermal parameters can be used for modelling future 32 /spl times/ 32 pixel arrays. In addition we operated three pixels in a 5 /spl times/ 5 array of microcalorimeters and find that the pixel to pixel reproducibility is very good. When used as an X-ray microcalorimeter individual pixels have a thermal decay time of 200 /spl mu/s is and their energy resolution is between 6 and 7 eV for 5.89 keV X-ray photons

Evaluation of Percolation Ponds for Design and Operation

Land application of domestic wastewater effluent by rapid rate infiltration (i.e., percolation ponds) is a very successful and cost-effective method for wastewater management. Municipal percolation pond systems have been successfully operated in the United States for about 100 years. The disposal concept depends on a relatively high rate of secondary wastewater effluent infiltration into the soil by rapid percolation, either vertically or horizontally, away from the application surface area. This study was accomplished to determine infiltration rates at two working percolation pond systems and the variability of these rates, to compare the operating results with the initial design, and to create a stochastic computer based simulation program for design and operation. The initial study site was located west of Orlando, Florida, and consisted of a system of two percolation ponds. Daily readings were obtained on evaporation, rainfall, flow to the ponds, pond depth and groundwater table elevations. A mass balance inventory equation was formulated and the infiltration parameter was determined. A frequency distribution was created for the rainfall, evaporation and calculated infiltration from the initial site, and then a stochastic computer based simulation program was written with this data. The program calculated results which compared favorably with the design for this initial percolation pond site. A second site was chosen, also located in the Orlando area, to confirm the usefulness of the program and its operational capabilities

Das Internationale Jahr der Behinderten 1981 in historischer Perspektive

Political Culture and National Identit