A Numerical Study of the Development of Inducer Backflow

Inducers are used as a first stage in pumps to hinder cavitation and promote stable flow. Inducers pressurize the working fluid sufficiently such that cavitation does not develop in the rest of the pump, which allows the pump to operate at lower inlet head conditions. Despite the distinct advantages of inducer use, an undesirable region of backflow and resulting cavitation can form near the tips of the inducer blades. This backflow is often attributed to tip leakage flow, or the flow induced by the pressure differential across an inducer blade at the tip. We examine backflow of a single inducer geometry at varying flow coefficients with a tip clearance of τ = 0.32%, and no tip clearance. Removing the tip clearance prevents tip leakage flow. At all flow coefficients below design, we observe backflow penetrating up to 14% further upstream in the inducer with no tip clearance. The backflow region in the inducer with no tip clearance experiences higher velocities and extends further into the core flow. However, the inducer with tip clearance develops a larger vortex at the leading edge of the blades. A comprehensive analysis of these simulations suggests that diffusion as the working fluid is loaded onto the blades, not tip leakage flow, is the driving force for the formation of backflow

Cavitation Inception and Performance of a Centrifugal Impeller During Startup

Rapid acceleration of rocket engine turbopumps during start-up imparts significant transient effects to the resulting flow field, causing pump performance to vary widely when compared to quasi-steady operation. To improve turbopump design in response to the transient effects of start-up this paper presents a method to simulate turbopump startup using CFD. Cavitating pump performance is initially evaluated using a simulation with a constant outlet pressure boundary condition. Based on the difference between simulation inlet pressure and target inlet pressure, the defined pressure on the outlet boundary condition is modified. This process is repeated until simulation inlet pressure is essentially constant during start-up. Using this simulation method, the performance of a centrifugal turbopump during start-up is simulated. Reasonable solution convergence is reached in one single phase and four cavitating simulation iterations. After these five simulation iterations, the average error between inlet pressure and inlet target pressure is 10%. Cavitating simulation iterations 3 and 4 agree within 11% on average for inlet total pressure during startup, 0:1% on average for head coefficient, 13% on average for cavitation volume, 20% on average for flow coefficient, and 2% on average for RMS force on the impeller. The agreement between simulation iterations 3 and 4 suggests that a reasonable solution has been reached

COMMERCIAL BEEF HERD REPLACEMENT STRATEGIES

Annualized cow ownership costs represent a large component of the total costs in a cow-calf enterprise, and therefore impact profitability. Annualized cow costs are determined in large part by the price or cost of that cow when it entered the herd. We find that ownership costs, and in turn cow-herd profitability, can be significantly impacted by heifer replacement strategies. Timing (within the cattle cycle) and method (raise vs. purchase) are both important considerations.Livestock Production/Industries,

The early evolution of land plants, from fossils to genomics: a commentary on Lang (1937) ‘On the plant-remains from the Downtonian of England and Wales'

© 2015 The Authors. Published by the Royal Society under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/4.0/, which permits unrestricted use, provided the original author and source are credited. The file attached is the published version of the article

Monitoring of Potential N Losses from Dairy and Organic Farming Systems

End of Project ReportThe project was carried out at Johnstown Castle and was concerned with monitoring potential nitrogen (N) leaching losses from organic and dairy farming systems. Some plots were cut for silage in year one; only grazed plots were used in year two. There were low input manure N plots in the organic system with low and high input fertiliser N plots in the dairy system. Soil samples, in 15 cm intervals from the surface to 90cm deep, were taken in triplicate from one plot of each treatment on three successive days per month from October to March in year 1 and from September to March in year 2. Extraction of nitrate-N (NO3-N) and ammonium-N (NH4- N) was carried out on un-bulked soil cores by taking a 20 g sub-sample and using 100 ml 2 molar KCl. A 20 g sub-sample of each day`s bulked replicates was dried at 105 degrees C overnight for moisture determination. The concentrations of NO3-N and NH4-N in the extracts were determined on an automatic analyser and the results were converted to kg per ha using the following bulk densities for the soil layers: 0-15, 15-30, 30-60, 60-90, 1.3, 1.4, 1.6, 1.75 g per cm3, respectively. In year 1 the results showed no significant difference between treatments in the level of NO3-N, NH4-N and total mineral N in the soil layers and total amounts to 90 cm. On four of the six dates, November, December, January, early-March, the level of total mineral N was lowest in the low N treatment. Among treatments, NH4-N was lowest in the low N treatment on four dates, November, December, January, early-March while NO3-N was also lowest on four dates, November, December, early-March and late-March. At the November, December, January and early-March sampling, the organic farm NH4-N data to 90 cm was highest which was reflected in the total mineral N results to 90 cm for November, December and early-March. In year 2 the results showed no significant difference between treatments in the level of NO3- N, NH4-N and total mineral N in the soil layers and total amounts to 90 cm. In September, October, November, December and February, total mineral N to 90 cm was highest in the high N treatment. This was a reflection of high NO3-N levels in that treatment for those sampling dates. Among treatments, total mineral N to 90 cm was lowest in the organic farm samples in September, October, November, December and February. This result reflected, among treatments, lowest NH4-N levels in September, October, November, December, February and lowest NO3- N levels in November and December. Estimates of the amounts of applied N leached, averaged over the two years of the experiment, were 22% for the Low N treatment and 12% for the High N treatment. An equation, developed from studies carried out in County Cork (Richards, 1999), gave predictions of N available for leaching in November from the N treatments in year 2 which were in very good agreement at low N and within 23% of those actually recorded at high N. Assessment of available N leaching models led to the conclusion that the relatively simple UK `N Cycle` model was most adaptable to Irish conditions since other European and US models require input parameters not readily available including those for soil texture, soil hydrology and soil organic matter.European Union Structural Funding (EAGGF

Transparency and communication in Norwegian and Nova Scotian Atlantic salmon aquaculture industries

The Atlantic salmon aquaculture industry has the potential to make a significant contribution to economic development and seafood production globally – particularly in rural and coastal communities. However, the lack of social licence to operate (SLO) can become a barrier for industry development. Greater transparency and communication have been suggested as two of the potential drivers for the industry to achieve SLO. This study explores the role of transparency and communication in the achievement of SLO in the salmon aquaculture industry by contrasting the perceptions of relevant stakeholders (researchers, managers/regulators, NGOs/ community groups, and industry). The comparison was carried out in Norway, having national ocean policies incorporating SLO, and Nova Scotia, Canada, that has adopted new aquaculture regulations in 2015 following a three-year moratorium. Results highlight the need for industry to take on a leadership role in transparency and communication. Results also reinforce the importance of meaningful engagement and reporting of environmental standards, but also the need to monitor and report social standards. Comparison of Norway and Nova Scotia helps to understand the role of transparency and communication in achieving SLO, which may be key to promoting the development and sustainability of the salmon aquaculture industry worldwide.publishedVersio

High level of treatment failure with commonly used anthelmintics on Irish sheep farms

peer-reviewedBackground: In 2013 a Technology Adoption Program for sheep farmers was established to encourage the implementation of best management practices on sheep farms in Ireland. There were 4,500 participants in this programme in 2013. As part of this programme, farmers had the option to carry out a drench test to establish the efficacy of their anthelmintic treatment. Results: Flock faecal samples were collected before and after treatment administration and gastrointestinal nematode eggs enumerated. In total there were 1,893 participants in the task, however only 1,585 included both a pre- and post-treatment faecal sample. Of those, 1,308 provided information on the anthelmintic product that they used with 46%, 23% and 28% using a benzimidazole (BZ), levamisole (LEV) and macrocyclic lactone (ML) product respectively. The remaining farmers used a product inapplicable for inclusion in the task such as a flukicide or BZ/LEV combination product. Samples were included for analysis of drench efficacy if the pre-treatment flock egg count was ≥200 eggs per gram and the interval post-sampling was 10–14 days for BZ products, 4–7 days for LEV products and 14–18 days for ML products. These criteria reduced the number of valid tests to 369, 19.5% of all tests conducted. If the reduction post-treatment was ≥95% the treatment was considered effective. Only 51% of treatments were considered effective using this criterion. There was a significant difference in efficacy between the anthelmintic drug classes with BZ effective in only 30% of treatments, LEV effective in 52% of cases and ML effective in 76% of cases. Conclusions: Gastrointestinal nematode anthelmintic treatments, as practiced on Irish farms, have a high failure rate. There was a significant difference between the efficacies of the anthelmintic classes with BZ the least effective and ML the most effective

Archean granite-greenstone tectonics at Kolar (South India): Interplay of diapirism and bulk inhomogeneous contraction during juvenile magmatic accretion

[1] The structural study of the Kolar greenstone belt and surrounding granite-gneiss terrains combined with U-Pb dating reveals that the middle and lower crustal tectonoplutonic pattern of the eastern Dharwar craton developed during a major magmatic accretion event between 2550 and 2530 Ma. The granite-greenstone pattern resulted from the interference of gravity-driven sagging of the greenstones (i.e., diapirism), E-W bulk inhomogeneous shortening combined with horizontal N-S stretching, and syntectonic juvenile pluton emplacement. Bulk inhomogeneous contraction is accommodated by the synchronous development of a pervasive, N-S trending vertical foliation, shallow stretching lineation, and conjugate strike-slip shear zone pattern within and outside the greenstone belt, resulting in regional horizontal pure shear deformation. The plutons around the greenstone belt record regional contraction by developing one set of strike-slip C-S fabrics of the shear zone pattern. The development of the granite-greenstone pattern was coeval and compatible with deformation during juvenile magmatic accretion, melting, and granulite metamorphism in the lower crust. The Kolar example points to a specific crustal rheology that allowed sagduction of the greenstones and regional distributed bulk inhomogeneous strain, due to mechanical homogeneity and low viscosity provided by large-scale melting during the accretion event. This example further suggests specific boundary conditions to the craton that allowed E-W inhomogeneous shortening to be accommodated by N-S stretching and spreading of the crust without significant tectonic thickening. Such tectonoplutonic pattern is specific to the Archean and may develop as a consequence of mantle plume activity in intracontinental settings

Characterization and Genetic Study of a Typical Prairie and a Typical Planosol of Eastern Oklahoma

Soil