Computer aided design and manufacturing of composite propfan blades for a cruise missile wind tunnel model

One of the propulsion concepts being investigated for future cruise missiles is advanced unducted propfans. To support the evaluation of this technology applied to the cruise missile, a joint DOD and NASA test project was conducted to design and then test the characteristics of the propfans on a 0.55-scale, cruise missile model in a NASA wind tunnel. The configuration selected for study is a counterrotating rearward swept propfan. The forward blade row, having six blades, rotates in a counterclockwise direction, and the aft blade row, having six blades, rotates in a clockwise direction, as viewed from aft of the test model. Figures show the overall cruise missile and propfan blade configurations. The objective of this test was to evaluate propfan performance and suitability as a viable propulsion option for next generation of cruise missiles. This paper details the concurrent computer aided design, engineering, and manufacturing of the carbon fiber/epoxy propfan blades as the NASA Lewis Research Center

Aluminium acetate solution in the treatment of chronic suppurative otitis media

Includes bibliographical references (p. 99-110)

Estimating Relevant Portion of Stability Region using Lyapunov Approach and Sum of Squares

Traditional Lyapunov based transient stability assessment approaches focus on identifying the stability region (SR) of the equilibrium point under study. When trying to estimate this region using Lyapunov functions, the shape of the final estimate is often limited by the degree of the function chosen, a limitation that results in conservativeness in the estimate of the SR. More conservative the estimate is in a particular region of state space, smaller is the estimate of the critical clearing time for disturbances that drive the system towards that region. In order to reduce this conservativeness, we propose a methodology that uses the disturbance trajectory data to skew the shape of the final Lyapunov based SR estimate. We exploit the advances made in the theory of sum of squares decomposition to algorithmically estimate this region. The effectiveness of this technique is demonstrated on a power systems classical model.Comment: Under review as a conference paper at IEEE PESGM 201

Financialization, crisis and commodity correlation dynamics

We study conditional volatility and correlation dynamics for returns to commodity fu- tures, stocks and bonds, from May 1990-July 2009 using DSTCC- GARCH. The models allow correlation to vary smoothly between extreme states via transition functions. Expected stock volatility (VIX) and money manager open interest in futures markets are relevant transition variables. Results show increasing integration between commodity futures and stocks: com- modity returns volatility is predicted by common factors but also by .nancial traders.open positions. We observe higher and more variable correlations between commodity futures and stock returns from mid-sample, with many series showing a structural break in the conditional correlation processes from the late 1990s

The NASA-IGES geometry data exchange standard

Described here are the data exchange efforts and plans supported by the NASA Steering Committee for Surface Modeling and Grid Generation. Current methods for geometry data exchange between computer aided design (CAD) systems and NASA computational fluid dynamics (CFD) analysis systems are tedious and induce errors. A Geometry Data Exchange Standard is proposed, utilizing a subset of an existing national standard titled Initial Graphic Exchange Standard (IGES). Future plans for data exchange standardization include all aspects of CFD data. Software systems to utilize this NASA-IGES Geometry Data Exchange Specification are under development

Field Experiments on Responses of a Freshwater, Benthic Macroinvertebrate Community to Vertebrate Predators

We examined the seasonal importance of vertebrate predators in potentially regulating the abundance and diversity of the benthic macroinvertebrates in the littoral zone of a soft-bottom reservoir that receives thermal effluent from a nuclear production reactor. Thirty-six predator (fish and turtle) exclusion cages (4 m-') were placed in shallow water at six locations along a thermal gradient in Par Pond, a 1100-ha cooling reservoir on the Savannah River Plant near Aiken, South Carolina, USA. An additional 36 control plots (4 m-) were also set up. Cages were in place during three, 3-mo test periods beginning in September 1977. Estimates of benthic density, taxon richness, and distribution within functional groups (defined by feeding mechanism) were calculated for each test period. Effects of temperature on predator-prey relationships were also determined. Experimental results of this study suggest that vertebrate predation was not the fundamental parameter organizing the benthic macroinvertebrate community in the littoral zone of this reservoir. Neither taxon richness nor density of total macroinvertebrates was conclusively related to predator treatment. Relationships between predator treatment and community response (changes in density and taxon richness) were generally unaffected by either plot locality, temperature fluctuations from thermal effluent, or seasonal changes. When data from caged and control plots were pooled, however, both location and water temperature individually had direct impacts on the benthic community. From our results and other field studies we hypothesize that individual species of "keystone" benthic predators (Paine 1969b) do not occur in the littoral zone of freshwater lentic environments with soft bottoms. This hypothesis is based on the following four arguments. First, environmental heterogeneity should reduce predator efficiency relative to that found in rocky intertidal systems where keystone predation may be present. Second, relative food web complexity should reduce the community importance of an individual predator species. Third, the apparent relatively greater resource partitioning of space and food in the freshwater littoral zone hinders monopolization of ratelimiting environmental resources by a single dominant prey species. Fourth, the effects of predation may not be extensive enough in time or area to provide sufficient resource space (and thus food) for exploitation by fugitive species. Possible regulation by a guild of predators and cases where the general hypothesis might be falsified are discussed

Carbon isotope ratios of Sterkfontein fossils indicate a marked shift to open environments c.1.7 Myr ago

Sterkfontein straddles a period in the Plio-Pleistocene in which the effects of global-scale climate shifts on continental environments and biota are not yet well understood. Reconstructions based on faunal indicators have suggested incremental shifts from relatively closed, mesic landscapes to open, arid environments at this time. We examined environmental shifts from ~2.5 to 1.7 million years ago (Myr) using a C3 / C4 index derived from 13C / 12C data on bovid fossils from Sterkfontein. Data for Member 4 and the Member 5 East infill indicate persistence of a wooded to moderately wooded environment until about 2.0-1.8 Myr. Data indicating a marked shift to open environments are observed only for the younger Member 5 West infill. We conclude that the major shift to open environments occurred near 1.7 Myr rather than at c. 2.5 Myr

Diagnosis of bacterial vaginosis from self-obtained vaginal swabs.

OBJECTIVE: To determine the concordance between vaginal fluid Gram stains and pH obtained at speculum exam with similar stains and pH prepared from self-obtained vaginal swabs. METHODS: Using vaginal fluid Gram stain, 129 pregnant women were screened for bacterial vaginosis at 24 to 29 weeks' gestation. Two smears were collected from each woman during the same prenatal visit: the first was prepared from a self-obtained vaginal swab and the second from a physician-obtained speculum examination. Vaginal pH was recorded for each swab. Kappa coefficient was used to quantify agreement between the two sets of results. RESULTS: When compared with the physician-obtained smear, the ability of the self-obtained Gram stain to diagnose bacterial vaginosis had a sensitivity of 77%, specificity of 97%, positive predictive value of 71% and negative predictive value of 97%. There was substantial agreement (weighted kappa=0.82) between the two techniques in the ability to determine the grade of vaginal flora. CONCLUSION: When compared with physician-obtained vaginal smears, self-obtained smears have substantial agreement in the diagnosis of bacterial vaginosis