170 research outputs found

    Three-dimensional turbopump flowfield analysis

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    A program was conducted to develop a flow prediction method applicable to rocket turbopumps. The complex nature of a flowfield in turbopumps is described and examples of flowfields are discussed to illustrate that physics based models and analytical calculation procedures based on computational fluid dynamics (CFD) are needed to develop reliable design procedures for turbopumps. A CFD code developed at NASA ARC was used as the base code. The turbulence model and boundary conditions in the base code were modified, respectively, to: (1) compute transitional flows and account for extra rates of strain, e.g., rotation; and (2) compute surface heat transfer coefficients and allow computation through multistage turbomachines. Benchmark quality data from two and three-dimensional cascades were used to verify the code. The predictive capabilities of the present CFD code were demonstrated by computing the flow through a radial impeller and a multistage axial flow turbine. Results of the program indicate that the present code operated in a two-dimensional mode is a cost effective alternative to full three-dimensional calculations, and that it permits realistic predictions of unsteady loadings and losses for multistage machines

    Experiments on grain yield in a range of old and modern wheat varieties.

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    Growth, yield, water use and water use efficiency of old and modern wheat varieties in a mediterranean type environment, 87M17 and 87WH14. Ear and stem dry matter at anthesis and grain yield in a range of wheat varieties, 87M18

    Long term effects of direct drilling and conventional cultivation on the distribution of nutrients and organic c in soils of south Western Australia

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    This experiment was part of a long term tillage trial designed to examine the effect of various tillage systems on the yield of wheat on a range of agricultural soils in Western Australia. A subset of results from the main experiment is presented here.This report describes the distribution of extractable P, extractable K, total N, organic C, and pH at 6 depths in the soil from 6 locations; Wongan Hills, Merredin (H) (calcic, red-brown earth), Avondale, Merredin (L) (acid, yellow earth), Esperance and Mt Barker. Three tillage systems (conventional cultivation, direct drilled with a combine, direct drilled with a triple discdrill) and 2 nitrogen rates were applied, to sites of continuously cropped wheat. Developments were monitored for a period of 9 years.The concentrations of extractable nutrients and organic C in the surface layers of the soil were generally higher with direct drilling than with conventional cultivation. Differences between treatments were generally evident within the first three years of the experiment. The effect of tillage tended to be similar at all locations except Esperance, where tillage had no effect on the concentration of extractable nutrients or organic C in the soil. Conventionally cultivated sandy and sandy clay loam soils also tended to have a slightly higher pH than direct drilled soils

    Winter wheat roots grow twice as deep as spring wheat roots, is this important for N uptake and N leaching losses?

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    Cropping systems comprising winter catch crops followed by spring wheat could reduce N leaching risks compared to traditional winter wheat systems in humid climates. We studied the soil mineral N (Ninorg) and root growth of winter- and spring wheat to 2.5 m depth during three years. Root depth of winter wheat (2.2 m) was twice that of spring wheat, and this was related to much lower amounts of Ninorg in the 1 to 2.5 m layer after winter wheat (81 kg Ninorg ha-1 less). When growing winter catch crops before spring wheat, N content in the 1 to 2.5 m layer after spring wheat was not different from that after winter wheat. The results suggest that by virtue of its deep rooting, winter wheat may not lead to high levels of leaching as it is often assumed in humid climates. Deep soil and root measurements (below 1 m) in this experiment were essential to answer the questions we posed

    NCBI’s virus discovery codeathon: building “FIVE” —the Federated Index of Viral Experiments API index

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    Viruses represent important test cases for data federation due to their genome size and the rapid increase in sequence data in publicly available databases. However, some consequences of previously decentralized (unfederated) data are lack of consensus or comparisons between feature annotations. Unifying or displaying alternative annotations should be a priority both for communities with robust entry representation and for nascent communities with burgeoning data sources. To this end, during this three-day continuation of the Virus Hunting Toolkit codeathon series (VHT-2), a new integrated and federated viral index was elaborated. This Federated Index of Viral Experiments (FIVE) integrates pre-existing and novel functional and taxonomy annotations and virus–host pairings. Variability in the context of viral genomic diversity is often overlooked in virus databases. As a proof-of-concept, FIVE was the first attempt to include viral genome variation for HIV, the most well-studied human pathogen, through viral genome diversity graphs. As per the publication of this manuscript, FIVE is the first implementation of a virus-specific federated index of such scope. FIVE is coded in BigQuery for optimal access of large quantities of data and is publicly accessible. Many projects of database or index federation fail to provide easier alternatives to access or query information. To this end, a Python API query system was developed to enhance the accessibility of FIVE

    Expert Leadership and Hidden Inequalities in Community Projets

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    This chapter explores the development of a mid-range theory that can be used in organisations when considering how to engage multiple stakeholders in a project that requires expert input. The case study presented here is concerned with a ground-breaking approach to integrate heritage, culture and social benefit through the medium of archaeology and heritage. The findings indicated that the ‘expert’ as a leader of the project created hidden inequalities in the team, preventing the longer-term social outcomes of the project from materialising. A Realist Evaluation (Pawson and Tilley, 1997a) protocol was developed which created an ‘intervention’, permitting the non-linear complex interactions between multiple groups and multiple stakeholders to be observed and evaluated. This allowed for the political, strategic, organisational, operational and individual perspectives to be addressed making it a suited evaluative approach to this type of multiple stakeholder project
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