Boundary-layer analysis of subsonic inlet diffuser geometries for engines nacelles

Theoretical Mach number distributions and boundary-layer parameters are presented for subsonic nacelle inlet diffuser geometries with length to exit diameter ratios ranging from 0.4 to 1.6 and diffuser exit area to throat area ratios ranging from 1.1 to 2.0. The major portion of the study was done with a cubic diffuser contour with the inflection point at the midpoint of the diffuser, a diffuser throat Mach number of 0.6, and a free-stream Mach number of 0.12. Calculations were performed at both model (diffuser exit diameter, 30.5 cm) and full-scale (diffuser exit diameter, 183 cm) sizes. Separation limits were defined by establishing a separation boundary on plots of diffuser area ratio as a function of diffuser length to diameter ratio. The effects of diffuser contour, inlet lip geometry, and throat Mach number on the boundary-layer characteristics are illustrated. The major results of the study indicate that the separation boundary is shifted to greater area ratios by (1) increasing the diffuser length, (2) increasing the scale of the diffuser and, (3) moving the inflection point of the diffuser contour to or ahead of the midpoint of the diffuser

Comparison of experimental and theoretical boundary-layer separation for inlets at incidence angle at low-speed conditions

Comparisons between experimental and theoretical Mach number distributions and separation locations are presented for the internal surfaces of four different subsonic inlet geometries with exit diameters of 13.97 centimeters. The free stream Mach number was held constant at 0.127, the one-dimensional throat Mach number ranged from 0.49 to 0.71, and the incidence angle ranged from 0 deg to 50 deg. Generally good agreement was found between the theoretical and experimental surface Mach number distributions as long as no flow separation existed. At high incidence angles, where separation was obvious in the experimental data, the theory predicted separation on the lip. At lower incidence angles, the theoretical results indicated diffuser separation which was not obvious from the experimental surface Mach number distributions. As incidence angle was varied from 0 deg to 50 deg, the predicted separation location shifted from the diffuser region to the inlet highlight. Relatively small total pressure losses were obtained when the predicted separation location was greater than 0.6 of the distance between the highlight and the diffuser exit

Preliminary Analysis Of Interteachings Frequent Examinations Component In The Community College Classroom

Interteaching has shown to be an effective alternative to traditional lecture in a number of studies, but thorough analyses of its components, including frequent exams, is limited. Research suggests that increasing the frequency of exams may improve student learning. This study assessed the effectiveness of interteachings frequent exams component on student exam scores in two introductory psychology course sections at a community college. Six unit exams were given to Section 1 and 12 to Section 2. Both sections received identical pretests and posttests. Although statistically insignificant, Section 2 consistently scored better or equal to Section 1 on all exams. Section 2 also produced a greater difference between pretest and posttest scores. Although not reaching traditionally significant levels, the results suggest that students given frequent exams may achieve higher exam scores and increase retention of overall course material

Geography Agriculture Photo Essay

Students will use the creativity of photography to show understanding of the 5 themes of geography

Economics of Agriculture

Students will be able to identify and explain the factors that cause shifts in agriculture’s supply and demand

Biphosphonate-Mediated Gene Vector Delivery from the Metal Surfaces of Stents

The clinical use of metallic expandable intravascular stents has resulted in imporved therapeutic outcomes for coronary artery disease. However, arterial reobstruction after stenting, in-stent restenosis, remains an important problem. Gene therapy to treat in-stent restenosis by using gene vector delivery from the metallic stent surfaces has never been demonstrated. The present studies investigated the hypothesis that metal-biphosphonate binding can enable site-specific gene vector delivery from metal surfaces. Polyallylamine biphosphonate (PAA-BP) was synthesized by using Michael addition methodology. Exposure to aqueous solutions of PAA-BP resulted in the formation of a monomolecular biphosphonate later on metal alloy surfaces (steel, nitinol, and cobalt-chromium), as demonstrated by x-ray photoelectron spectroscopy. Surface-bound PAA-BP enabled adenoviral (Ad) tethering due to covalent thiol-binding of either anti-Ad antibody or a recombinant Ad-receptor protein, D1. In arterial smooth muscle cell cultures, alloy samples configured with surface-tethered Ad were demonstrated to achieve site-specific transduction with a reporter gene, (GFP). Rat carotid stent angioplasties using metal stents exposed to aqueous PAA-BP and derivatized with anti-knob antibody or D1 resulted in extensive localized Ad-GFP expression in the arterial wall. In a separate study with a model therapeutic vector, Ad-inducible nitric oxide synthase (iNOS) attached to the biphosphonate-treated metal stent surface via D1, significant inhibition of restenosis was demonstrated (neointimal/media ration 1.68 ± 0.27 and 3.4 ± 0.35; Ad-iNOS vs. control, P \u3c 0.01). Is is concluded that effective gene vector delivery from metallic stent surfaces can be achieved using this approach

Phylogenetic Distribution of CRISPR-Cas Systems in Antibiotic-Resistant Pseudomonas aeruginosa

Pseudomonas aeruginosa is an antibiotic-refractory pathogen with a large genome and extensive genotypic diversity. Historically, P. aeruginosa has been a major model system for understanding the molecular mechanisms underlying type I clustered regularly interspaced short palindromic repeat (CRISPR) and CRISPR-associated protein (CRISPR-Cas)-based bacterial immune system function. However, little information on the phylogenetic distribution and potential role of these CRISPR-Cas systems in molding the P. aeruginosa accessory genome and antibiotic resistance elements is known. Computational approaches were used to identify and characterize CRISPR-Cas systems within 672 genomes, and in the process, we identified a previously unreported and putatively mobile type I-C P. aeruginosa CRISPR-Cas system. Furthermore, genomes harboring noninhibited type I-F and I-E CRISPR-Cas systems were on average ~300 kb smaller than those without a CRISPR-Cas system. In silico analysis demonstrated that the accessory genome (n = 22,036 genes) harbored the majority of identified CRISPR-Cas targets. We also assembled a global spacer library that aided the identification of difficult-to-characterize mobile genetic elements within next-generation sequencing (NGS) data and allowed CRISPR typing of a majority of P. aeruginosa strains. In summary, our analysis demonstrated that CRISPR-Cas systems play an important role in shaping the accessory genomes of globally distributed P. aeruginosa isolates

A Search for Impact Glass in the Sirius Formation, Transantarctic Mountains, Antarctica

Much debate surrounds the history of Pliocene marine diatoms emplaced in the Sirius Group, a diamictite found at the peaks of the Transantarctic Mountains, Antarctica. Hypotheses as to their origin include a retreat of the East Antarctic ice sheet 2-3 million years ago and flooding of interior continental basins to deposit the diatoms, eolian transport of diatoms from marine and terrestrial sources across a stable East Antarctic ice sheet from at least 8-11 million years ago, and an impact event large enough to cause displacement and rainfall of marine debris ca. 2 million years ago. I present chemical analyses of samples of the Cenozoic (specific age unknown) Sirius Group collected from Mt. Sirius in the Transantarctic Mountains, Antarctica, in search of impact glass potentially created from a large impact event. Weight percent oxide totals range from 102% - 60%. From the usable chemical analyses of 122 points across 76 grains, I identified the following: calcite or aragonite (38.5%), pyroxene (36.1%), plagioclase (18.0%), quartz (5.7%) and apatite (1.6%). The pyroxene grains are chiefly augite and ferroaugite. The plagioclase is mostly Ca-rich (bytownite and labradorite). The remaining analyses not identified could be impact glass, crystallinity could not be determined