Induced velocity field of a jet in a crossflow

An experimental investigation of a subsonic round jet exhausting perpendicularly from a flat plate into a subsonic crosswind of the same temperature was conducted. Velocity and pressure measurements were made in planes perpendicular to the path of the jet for ratios of jet velocity to crossflow velocity ranging from 3 to 10. The results of these measurements are presented in tabular and graphical forms. A pair of diffuse contrarotating vortices is identified as a significant feature of the flow, and the characteristics of the vortices are discussed

Velocity field of a round jet in a cross flow for various jet injection angles and velocity ratios

A subsonic round jet injected from a flat plate into a subsonic crosswind of the same temperature was investigated. Velocity and pressure measurements in planes perpendicular to the path of the jet were made for nominal jet injection angles of 45 deg, 60 deg, 75 deg, 90 deg, and 105 deg and for jet/cross flow velocity ratios of four and eight. The velocity measurements were obtained to infer the properties of the vortex pair associated with a jet in a cross flow. Jet centerline and vortex trajectories were determined and fit with an empirical equation that includes the effects of jet injection angle, jet core length, and jet/cross flow velocity ratios

Induced pressure distribution of a jet in a crossflow

The turbulent flow of a subsonic round jet exhausting perpendicularly from a flat plate into a subsonic crosswind of the same temperature was investigated in the Langley V/STOL tunnel. The large test section of this tunnel made it possible to use a jet with the relatively large diameter of 10.16 cm. Pressures were measured on the flat plate at over 400 locations to provide a detailed description of the static pressure distribution. Results are presented in tabular and graphical forms for jet to crossflow velocity ratios ranging from 2 to 10, and comparisons are made with results of other experiments. The results indicate that the dominant flow parameter affecting the pressure distributions is the ratio of jet to crossflow velocities. The distribution of turbulence on the plate also appears to be a function of velocity ratio

Effects of wing leading-edge deflection on low-speed aerodynamic characteristics of a low-aspect-ratio highly swept arrow-wing configuration

Static force tests were conducted in the Langley V/STOL tunnel at a Reynolds number (based on the mean aerodynamic chord) of about 2.0 x 10 to the 6th power for an angle-of-attack range from about - 10 deg to 17 deg and angles of sideslip of 0 and + or - 5 deg. Limited flow visualization studies were also conducted in order to provide a qualitative assessment of leading-edge upwash characteristics

The effect of 12 weeks of combined upper- and lower-body high-intensity interval training on muscular and cardiorespiratory fitness in older adults

Background: High-intensity interval training (HIT) can impact cardiorespiratory and muscular fitness simultaneously, yet protocols typically focus on lower-body exercise. For older adults however, performing activities of daily living requires upper- and lower-body fitness. Aims: To assess the effects of combined upper- and lower-body HIT on fitness in adults aged > 50 years. Methods: Thirty-six adults (50–81 years; 21 male) were assigned via minimisation to either HIT (n = 18) or a no-exercise control group (CON, n = 18) following baseline assessment of leg extensor muscle power, handgrip strength, cardiorespiratory fitness (predicted VO2max) and health-related quality of life (HRQoL). The HIT group completed two training sessions per week for 12-weeks, performing a combination of upper-, lower- and full-body exercises using a novel hydraulic resistance ergometer. Data were analysed via ANCOVA with probabilistic inferences made about the clinical relevance of observed effects. Results: All participants completed the intervention with mean (82 ± 6%HRmax) and peak (89 ± 6%HRmax) exercise heart rates confirming a high-intensity training stimulus. Compared with CON, HIT showed possibly small beneficial effects for dominant leg power (10.5%; 90% confidence interval 2.4–19.4%), non-dominant leg power (9.4%; 3.3–16.0%) and non-dominant handgrip strength (6.3%; 1.2–11.5%) while the intervention effect was likely trivial (5.9%; 0.5–11.5%) for dominant handgrip strength. There was a likely small beneficial effect for predicted VO2max (8.4%; 1.8–15.4%) and small-moderate improvements across several domains of HRQoL. Conclusion: Combined upper- and lower-body HIT has small clinically relevant beneficial effects on muscular and cardiorespiratory fitness in older adults

Detecting 6 MV X-rays using an organic photovoltaic device

An organic photovoltaic (OPV) device has been used in conjunction with a flexible inorganic phosphor to produce a radiation tolerant, efficient and linear detector for 6 MV Xrays. The OPVs were based on a blend of poly(3-hexylthiophene-2,5-diyl) (P3HT) and phenyl-C61-butyric acid methyl ester (PCBM). We show that the devices have a sensitivity an order of magnitude higher than a commercial silicon detector used as a reference. Exposure to 360 Grays of radiation resulted in a small (2%) degradation in performance demonstrating that these detectors have the potential to be used as flexible, real-time, in vivo dosimeters for oncology treatments. (C) 2009 Elsevier B.V. All rights reserved

Assessment Of Aging Structures And Recruitment Of Walleye Sander Vitreus In Cedar Bluff Reservoir

Most walleye Sander vitreus populations in Kansas are supplemented or sustained with stocking. In 2006, gamete collection for hatchery production was initiated at Cedar Bluff Reservoir because the walleye population has a high abundance of potential brood fish and has been sustained by natural reproduction since 2001. However, no quantitative index has been developed to assess walleye recruitment in this fishery. Accordingly, from July through November 2010, I evaluated catch-per-unit-effort (overnight sets) of age-0 walleye in 19 and 25-mm mesh gill nets biweekly and at random and standard sites. There was not a significant difference in catch-per-unit-effort between site types (t = -0.04, df = 142, P = 0.97) or mesh sizes (n = 144, U = 2,154, P = 0.07). Recruitment also can be evaluated with a one-time age structure sample. Therefore, the precision among age estimates was evaluated through taking a sample of 95 walleye: (1) by comparing age estimates between two readers, and (2) the consistency of estimates from one reader among hard structures, by evaluating age bias plots, age frequency tables, and coefficients of variation derived from scales, sagittal otoliths, and sectioned sagittal otoliths. Best fit regression slopes from age bias plots derived with otoliths and sectioned otoliths were not significantly different from a slope of one (t = 1.39, df = 2, P \u3c 0.01; t = 0.44, df = 2, P \u3c 0.01) suggesting strong agreement among estimates. However, the best fit regression slope derived by using scales was significantly different from one (t = -3.42, df = 2, P \u3c 0.01), suggesting scales did not provide adequate precision for additional recruitment analyses. Age structure data were utilized, ages estimated from 210 fish (5 to 6 individuals in each 10 mm length group) and then extrapolated to a sample of un-aged fish (n = 928) based on size classes, to evaluate recruitment variability with the Recruitment Variability Index. The Recruitment Variability Index estimate was 0.69 and similar to estimates from over a decade earlier suggesting consistent recruitment in this population. An age structure was also used and historical catch-per-unit-effort of age-0 walleye to evaluate their utility in predicting year-class strength. Historical catch-per-unit-effort of age-0 walleye explained 72% (adjusted r2 value) of the variation in the current estimated size of the corresponding year-classes (F = 29.29, df = 11, P \u3c 0.01). Natural reproduction appears to be sustaining both walleye population and gamete harvest at Cedar Bluff Reservoir

Can an Invasive Species of Crayfish Help Save a Population of a Threatened Species of Bird, the King Rail?

ABSTRACT - Invasive species are frequently harmful to native species and to ecosystem stability. Yet, in a few cases, alien species have been found to benefit native residents. I investigated the relationship between a threatened species of marsh bird and an invasive species of crayfish on which it feeds. The Red Swamp Crayfish, Procambarus clarkii, was deliberately introduced into an impoundment at Mackay Island National Wildlife Refuge (NWR) 25 years ago. The refuge hosts one of the largest breeding populations of King Rails Rallus elegans on the east coast of the United States. This secretive marsh bird is globally Near Threatened (Birdlife International). The King Rail is mainly carnivorous and feeds in the shallows on fish, crustaceans, and other aquatic animals, with crayfish being a preferred food. The invasive crayfish is fast-growing and a prolific breeder. I investigated whether the crayfish could be providing these rare birds a resource that allows them to prosper here relative to other sites. Data were collected over the summer breeding season on both crayfish and rail abundance. I determined the distribution of crayfish among ten predetermined sites that were being surveyed for rail breeding density as part of an ongoing study. Crayfish were caught using food-baited traps. Carapace remains from consumed crayfish were collected as a representative sample of the segment of the population that fell prey. The rail population was surveyed via passive recording of calls using autonomous recording units (Wildlife Acoustics). Both species preferred areas of natural marsh compared to impoundments. I investigated whether peak numbers of the largest size class of the invasive species, P. clarkii, coincided with the brood rearing period, when King Rails would likely be most nutritionally stressed. The temporal data revealed that King Rail hatching dates peaked when the largest crayfish size classes were most abundant. That King Rails timed their breeding so that hatching coincided with larger sizes of the invasive crayfish suggests that P. clarkii may have a positive effect on King Rail population growth at this site. Relative rail abundance based on calling rates among sites was then compared to crayfish abundance at the same sites based on trap data to see if these were correlated. The spatial results of the study showed that when comparing P. clarkii abundance and King Rail relative density at ten locations, there was no significant relationship between higher numbers of crayfish and where rails chose to nest. Dietary constraints may have contributed to the decline of King Rail populations across its range, and its extirpation from marshes where vegetation, water depth and other habitat variables appear suitable. Further research will be needed to reveal what proportion of the diet of Mackay Island King Rails the crayfish represent, and whether the invasive species, P. clarkii, is a contributing substantially to their reproductive success