The x ray reflectivity of the AXAF VETA-I optics

The x-ray reflectivity of the VETA-I optic, the outermost shell of the AXAF x-ray telescope, with a bare Zerodur surface, is measured and compared with theoretical predictions. Measurements made at energies of 0.28, 0.9, 1.5, 2.1, and 2.3 keV are compared with predictions based on ray trace calculations. The data were obtained at the x-ray calibrations facility at Marshall Space Flight Center with an electron impact x-ray source located 528 m from the grazing incidence mirror. The source used photoelectric absorption filters to eliminate bremsstrahlung continuum. The mirror has a diameter of 1.2 m and a focal length of 10 m. The incident and reflected x-ray flux are detected using two proportional counters, one located in the incident beam of x-rays at the entrance aperture of the VETA-I, and the other in the focal plane behind an aperture of variable size. Results on the variation of the reflectivity with energy as well as the absolute value of the reflectivity are presented. We also present a synchrotron reflectivity measurement with high energy resolution over the range 0.26 to 1.8 keV on a flat Zerodur sample, done at NSLS. We present evidence for contamination of the flat by a thin layer of carbon on the surface, and the possibility of alteration of the surface composition of the VETA-I mirror perhaps by the polishing technique. The overall agreement between the measured and calculated effective area of VETA-I is between 2.6 percent and 10 percent, depending on which model for the surface composition is adopted. Measurements at individual energies deviate from the best-fitting calculation to 0.3 to 0.8 percent, averaging 0.6 percent at energies below the high energy cutoff of the mirror reflectivity, and are as high as 20.7 percent at the cutoff. We also discuss the approach to the final preflight calibration of the full AXAF flight mirror

Thermoelectric Applications to Truck Essential Power

The subjects covered in this report are: thermoelectrics, 1-kW generator for diesel engine; self-powered heater; power for wireless data transmission; and quantum-well thermoelectrics

Projected Climate Change Impacts on the Hydrology and Temperature of Pacific Northwest Rivers

A dominant river-tracing-based streamflow and temperature (DRTT) model was developed by coupling stream thermal dynamics with a source-sink routing model. The DRTT model was applied using 1/16 degree (similar to 6 km) resolution gridded daily surface meteorology inputs over a similar to 988,000 km(2) Pacific Northwest (PNW) domain to produce regional daily streamflow and temperature simulations from 1996 to 2005. The DRTT results showed favorable performance for simulation of daily stream temperature (mean R-2 = 0.72 and root-mean-square error = 2.35 degrees C) and discharge (mean R-2 = 0.52 and annual relative error 14%) against observations from 12 PNW streams. The DRTT was then applied with a macroscale hydrologic model to predict streamflow and temperature changes under historical (1980s) and future (2020s, 2040s, and 2080s) climate change scenarios (IPCC AR4) as they may affect current and future patterns of freshwater salmon habitat and associated productivity of PNW streams. The model projected a 3.5% decrease in mean annual streamflow for the 2020s and 0.6% and 5.5% increases for the 2040s and 2080s, respectively, with projected increase in mean annual stream temperatures from 0.55 degrees C (2020s) to 1.68 degrees C (2080s). However, summer streamflow decreased from 19.3% (2020s) to 30.3% (2080s), while mean summer stream temperatures warmed from 0.92 degrees C to 2.10 degrees C. The simulations indicate that projected climate change will have greater impacts on snow dominant streams, with lower summer streamflows and warmer summer stream temperature changes relative to transient and rain dominant regimes. Lower summer flows combined with warmer stream temperatures suggest a future with widespread increased summertime thermal stress for coldwater fish in the PNW region

Multi-Mission Capable, High g Load mW RPS

Over the past few years Hi-Z has been developing a wide range of mW generators and life testing thermoelectric modules for the Department of Energy (DOE) to fulfill requirements by NASA Ames and other agencies. The purpose of this report is to determine the capabilities of a wide range of mW generators for various missions. In the 1st quarterly report the power output of various mW generators was determined via thermal and mechanical modeling. The variable attributes of each generator modeled were: the number of RHUs (1-8), generator outer diameter (1.25-4 in.), and G-load (10, 500, or 2,000). The resultant power output was as high as 180 mW for the largest generator with the lowest Gload. Specifically, we looked at the design of a generator for high G loading that is insulated with Xenon gas and multifoil solid insulation. Because the design of this new generator varied considerably from the previous generator design, it was necessary to show in detail how it is to be assembled, calculate them as of the generator and determine the heat loss from the system. A new method of assembling the RHU was also included as part of the design. As a side issue we redesigned the test stations to provide better control of the cold sink temperature. This will help in reducing the test data by eliminating the need to 'normalize' the data to a specific temperature. In addition these new stations can be used to simulate the low ambient temperatures associated with Mars and other planets

Climate Change Predicted to Shift Wolverine Distributions, Connectivity, and Dispersal Corridors

Boreal species sensitive to the timing and duration of snow cover are particularly vulnerable to global climate change. Recent work has shown a link between wolverine (Gulo gulo) habitat and persistent spring snow cover through 15 May, the approximate end of the wolverine’s reproductive denning period. We modeled the distribution of snow cover within the Columbia, Upper Missouri, and Upper Colorado River Basins using a downscaled ensemble climate model. The ensemble model was based on the arithmetic mean of 10 global climate models (GCMs) that best fit historical climate trends and patterns within these three basins. Snow cover was estimated from resulting downscaled temperature and precipitation patterns using a hydrologic model. We bracketed our ensemble model predictions by analyzing warm (miroc 3.2) and cool (pcm1) downscaled GCMs. Because Moderate-Resolution Imaging Spectroradiometer (MODIS)-based snow cover relationships were analyzed at much finer grain than downscaled GCM output, we conducted a second analysis based on MODIS-based snow cover that persisted through 29 May, simulating the onset of spring two weeks earlier in the year. Based on the downscaled ensemble model, 67% of predicted spring snow cover will persist within the study area through 2030–2059, and 37% through 2070–2099. Estimated snow cover for the ensemble model during the period 2070– 2099 was similar to persistent MODIS snow cover through 29 May. Losses in snow cover were greatest at the southern periphery of the study area (Oregon, Utah, and New Mexico, USA) and least in British Columbia, Canada. Contiguous areas of spring snow cover become smaller and more isolated over time, but large (.1000 km2) contiguous areas of wolverine habitat are predicted to persist within the study area throughout the 21st century for all projections. Areas that retain snow cover throughout the 21st century are British Columbia, north-central Washington, northwestern Montana, and the Greater Yellowstone Area. By the late 21st century, dispersal modeling indicates that habitat isolation at or above levels associated with genetic isolation of wolverine populations becomes widespread. Overall, we expect wolverine habitat to persist throughout the species range at least for the first half of the 21st century, but populations will likely become smaller and more isolated

The relationship between elevation roughness and tornado activity: A spatial statistical model fit to data from the central great plains

The statistical relationship between elevation roughness and tornado activity is quantified using a spatial model that controls for the effect of population on the availability of reports. Across a large portion of the central Great Plains the model shows that areas with uniform elevation tend to have more tornadoes on average than areas with variable elevation. The effect amounts to a 2.3% [(1.6%, 3.0%) = 95% credible interval] increase in the rate of a tornado occurrence per meter of decrease in elevation roughness, defined as the highest minus the lowest elevation locally. The effect remains unchanged if the model is fit to the data starting with the year 1995. The effect strengthens for the set of intense tornadoes and is stronger using an alternative definition of roughness. The elevation-roughness effect appears to be strongest over Kansas, but it is statistically significant over a broad domain that extends from Texas to South Dakota. The research is important for developing a local climatological description of tornado occurrence rates across the tornado-prone region of the Great Plains

Thermal and optical analysis of a passive heat recovery and storage system for greenhouse skin

The thermal performance of a greenhouse can be greatly affected by the thermal and optical properties of its envelope system. In this study, a novel skin for greenhouse consisting of ethene-co-tetrafluoroethene (ETFE) membrane and Phase Change Material (PCM) RT28 has been developed and has also been experimentally investigated. The optical behaviour of the developed ETFE-Phase Change Material module sample is measured using a spectrometer and a pyranometer, respectively. The results show that at liquid state, the module has higher transmittance than that of at solid state. In addition, the light transmittance is related to the PCM's temperature. In the thermal aspect, the ETFE-Phase Change Material module presents different characterisation under various irradiances. Comparative analysis is also conducted for the ETFE-Phase Change Material, ETFE-water and ETFE alone. The ETFE-Phase Change Material system shows a benefit of the thermal management than that of other systems

Growth, polymorphism, and spatially controlled surface immobilization of biotinylated variants of IAPP(21-27) fibrils

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