4,416 research outputs found
Test vs. simulation
The following topics are presented in tabular form: (1) simulation capability assessments (no propulsion system test); (2) advanced vehicle simulation capability assessment; (3) systems tests identified events; (4) main propulsion test article (MPTA) testing evaluation; (5) Saturn 5, 1B, and 1 testing evaluation. Special vehicle simulation issues that are propulsion related are briefly addressed
Preliminary Investigation of the Effects of Rectangular Vortex Generators on the Performance of a Short 1.9:1 Straight-wall Annular Diffuser
Propulsion system ground testing
The objective is to provide management visibility relative to the roles of simulation and propulsion system testing for future development programs through assessment of current propulsion related simulation capabilities and review of contributions from propulsion system test programs. The presentation is represented by viewgraphs
Basic performance characteristics of several subsonic-diffuser-bypass-duct combinations for use with supersonic inlets
A Survey of Cenozoic Mammal Baramins
To expand the sample of statistical baraminology studies, we identified 80 datasets sampled from 29 mammalian orders, from which we performed 82 separate analyses. We analyzed each dataset with standard statistical baraminology techniques: baraminic distance correlation (BDC) and multidimensional scaling (MDS). We evaluated the BDC and MDS results from each character set for potential continuity and discontinuity. We found evidence of holobaramins in 57 of the 82 analyses (69.5%). Of the remaining character sets, three showed evidence of monobaramins and 22 (26.8%) were inconclusive. These results are consistent with previous efforts to test the discontinuity hypothesis, which found that a majority of character sets showed evidence of holobaramins. Tentative holobaramins represent 57 taxonomic groups, many of which have not been previously analyzed by statistical baraminology. Together with previously identified holobaramins, this study increases the number of putative mammal holobaramins to 64
How the Cervical Microbiota Contributes to Cervical Cancer Risk in Sub-Saharan Africa
Despite ongoing efforts, sub-Saharan Africa faces a higher cervical cancer burden than anywhere else in the world. Besides HPV infection, definitive factors of cervical cancer are still unclear. Particular states of the cervicovaginal microbiota and viral infections are associated with increased cervical cancer risk. Notably, HIV infection, which is prevalent in sub-Saharan Africa, greatly increases risk of cervicovaginal dysbiosis and cervical cancer. To better understand and address cervical cancer in sub-Saharan Africa, a better knowledge of the regional cervicovaginal microbiome is required This review establishes current knowledge of HPV, HIV, cervicovaginal infections, and the cervicovaginal microbiota in sub-Saharan Africa. Because population statistics are not available for the region, estimates are derived from smaller cohort studies. Microbiota associated with cervical inflammation have been found to be especially prevalent in sub-Saharan Africa, and to associate with increased cervical cancer risk. In addition to high prevalence and diversity of HIV and HPV, intracellular bacterial infections such as Chlamydia, Gonorrhea, and Mycoplasma hominis are much more common than in regions with a low burden of cervical cancer. This suggests the prevalence of cervical cancer in sub-Saharan Africa may be partially attributed to increased cervical inflammation resulting from higher likelihood of cervical infection and/or microbial dysbiosis
Minimum Cost Design of Water Distribution Systems
The objective of this study was to develop the analytical tools and procedures for minimum cost design of water distribution systems. Both analog and digital means of carrying out pressure and flow calculations were developed. As a result of this effort, digital programs for pressure and flow calculations in water distribution systems were written and have been widely distributed to practicing engineers. One procedure is based on a direct solution of the basic system equations using a linearization scheme and has several advantages over conventional techniques such as the Hardy Cross method. These include avoiding the need to initially balance the network and an assured convergence of the procedure.
Using this tool a procedure was developed for selecting pipe diameter which will result in a minimum cost design within the prescribed constraints. The method of steepest ascent and dynamic programming concepts were used to carry out the optimization. This procedure applies to closed loop\u27 systems without internal pumping. However, this work provides a basis for extending the concepts to more generalized water distribution systems
Effects of Diffuser and Center-body Length on Performance of Annular Diffusers with Constant-diameter Outer Walls and with Vortex-generator Flow Controls
Performance Characteristics of a 24 Degree Straight-Outer-Wall Annular-Diffuser-Tailpipe Combination Utilizing Rectangular Vortex Generators for Flow Control
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