4,758 research outputs found
GENESIS 2: Advanced lunar outpost
Advanced, second-generation lunar habitats for astronauts and mission specialists working on the Moon are investigated. The work was based on design constraints set forth in previous publications. Design recommendations are based on environmental response to the lunar environment, habitability, safety, near-term technology, replaceability and modularity, and suitability for NASA lunar research missions in the early 21st century. Scientists, engineers, and architects from NASA/JSC, Wisconsin aeronautical industry, and area universities gave technical input and offered critiques at design reviews throughout the process. The recommended design uses a lunar lava tube, with construction using a combination of Space Station Freedom-derived modules and lightweight Kevlar-laminate inflatables. The outpost includes research laboratories and biotron, crew quarters and support facility, mission control, health maintenance facility, and related areas for functional and psychological requirements. Furniture, specialized equipment, and lighting are included in the design analysis
Performance of two 10-lb/sec centrifugal compressors with different blade and shroud thicknesses operating over a range of Reynolds numbers
Centrifugal compressors often cannot be directly scaled to very small flow sizes because of structural and manufacturing limitations. The inability to directly scale all design parameters leads to a performance loss other than that which can be associated with the lower Reynolds number. A 10-lb/sec centrifugal compressor was scaled down to 2-lb/sec where adjustments to blade and shroud thickness and fillet radii were required. The modified 2-lb/sec compressor was then directly scaled back up to 10 lb/sec so that the effect of the modifications could be determined. The performance of the two 10-lb/sec compressors is compared over a range of speed and mass flow. The effect of variations in Reynolds number, impeller tip clearance, and shroud thickness on compressor performance is also presented
Estimating Procurement Cost Growth Using Logistic and Multiple Regression
Cost Growth in Department of Defense (DoD) major systems has been an ongoing problems for more than 30 years. Previous research has demonstrated the use of two-step logistic and multiple regression methodology to predicting cost growth produces desirable results traditional single-step regression. This research effort validates, and further explores the use of a two-step procedure for assessing DoD major weapon system cost growth using historical data. We compile programmatic data from the Selected Acquisition Reports (SARs) between 1990 and 2001 for programs covering all defense departments. Our analysis concentrates on cost growth in procurement dollar accounts for the Engineering and Manufacturing Development phase of acquisition. We investigate the use of logistic regression in cost growth analysis to predict whether or not procurement cost growth will occur in a program. If applicable, the multiple regression step is implemented to predict how much procurement cost growth will occur. Our study considers all seven SAR categories within the procurement accounts - engineering, schedule, estimating, support, quantity, economic, and other, but we refrain from analyzing these categories individually. Consequently, we focus on the total procurement cost growth incurred from these five categories during the Engineering and Manufacturing Development phase of acquisition
Chlorinated Hydrocarbon Residues in Pronghorn Antelope Antilocapra Americana americana (Ord) 1815 of South Dakota Collected in 1966
Man’s primary concerns have always been the struggle for survival and improvement of his lot. As his numbers increased, he attained greater ability to manipulate his environment. One method of manipulation has been through the use of insecticides. One of the largest uses of insecticides has been in connection with pest control on agricultural lands. Pest control has become of great economical significance within the past decades. Since South Dakota is primarily as agricultural state it has been caught up in this bioeconomical problem. One control method used has been the use of chlorinated hydrocarbon insecticides. (see more in text
Early Childhood Physical Environment Observation Schedules and Rating Scales: Preliminary Scales for the Measurement of the Physical Environment of Child Care Centers and Related Environments
This packet of schedules, scales, and procedures is intended for the systematic assessment of the quality of the physical environment of child care centers and related early childhood environments. Already in use in several places in North America, these instruments are reissued for research purposes only.https://dc.uwm.edu/caupr_mono/1040/thumbnail.jp
Predicting primary productivity in Westhampton Lake, Richmond, Virginia.
Several predictive photosynthetic models were tested using light, temperature, nutrient, chlorophyll, and primary productivity data collected from Westhampton Lake, Richmond, Virginia from February-September, 1972. A simple linear model, the Kendall rank correlation coefficient, was used to relate photosynthesis to individual meteorological, physical, chemical, and biological factors. iii Of the parameters measured, only the daily maximum photosynthetic efficiency ((P/chl) max ) was significantly correlated with photosynthesis. Five multiple factor (non-linear) models were tested. In the best fitting model, primary productivity was a function of the maximum observed ratio of photosynthesis/chlorophyll concentration, light intensity, temperature, nutrient concentrations, and chlorophyll concentration. The Pearson (r) correlation coefficient between predicted and observed values of photosynthesis for this model was .58, indicating that only 34% of the variability between predicted and observed values was accounted for by the model
Combining Taipan snake venom time/Ecarin time screening with the mixing studies of conventional assays increases detection rates of lupus anticoagulants in orally anticoagulated patients
<p>Abstract</p> <p>Background</p> <p>Oral anticoagulation compromises conventional lupus anticoagulant (LA) screening assays. Mixing studies can counteract the oral anticoagulant effect but the dilution reduces sensitivity and can generate false negative results. A firm diagnosis can be made from mixing studies when an elevated screen ratio is accompanied by a confirm ratio that generates significant correction to demonstrate phospholipid dependence, but also returns into the reference range, indicating complete normalisation of the oral anticoagulant effect. Taipan snake venom time (TSVT) with Ecarin time (ET) as a confirmatory test comprises an oral anticoagulant insensitive LA detection system and this study investigates the potential impact on detection rates when coupled with mixing studies on standard assays.</p> <p>Methods</p> <p>Eighty patients known to have LA who were receiving oral anticoagulation were tested with TSVT/ET and 1:1 mixing studies with normal plasma by dilute Russell's viper venom time (DRVVT) and dilute activated partial thromboplastin time (DAPTT) to assess detection rates by single and multiple assays.</p> <p>Results</p> <p>Thirty three of the 80 samples from known LA positive patients were positive in all three assays and 15 were positive in combinations of DRVVT, DAPTT or TSVT/ET. The remainder were positive in only one assay; 12 by DRVVT, 4 by DAPTT and 16 by TSVT/ET. Although all DRVVT and DAPTT positive mixing studies generated significant correction of the screen ratio by the confirm ratio, not all confirm ratios corrected back into the reference range. This was the case for 87.5% of the DRVVT results, 44.7% of the DAPTT results and 13.3% of the TSVT/ET positive mixing tests.</p> <p>Conclusion</p> <p>Addition of TSVT/ET screening for LA in orally anticoagulated patients could increase diagnostic efficacy either by detecting antibodies diluted in the mixing tests of conventional assays or those that do not react in DRVVT or DAPTT. Additionally, TSVT/ET can affirm the presence of a LA where conventional assay mixing tests may not have fully counteracted the oral anticoagulant effect but confirmatory test correction suggests the presence of a LA.</p
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