4,417 research outputs found

    Gas-to-hydraulic power converter

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    A gas piston driven hydraulic piston pump is described in which the gas cycle is of high efficiency by injecting the gas in slugs at the beginning of each power stroke. The hydraulic piston is disposed to operate inside the as piston, and the two pistons, both slidably but nonrotatably mounted, are coupled together with a rotating but non-sliding motion transfer ring extending into antifriction grooves in the sidewalls of the two pistons. To make the hydraulic piston move at a constant speed during constant hydraulic horsepower demand and thus exert a constant pressure on the hydraulic fluid, these grooves are machined with variable pitches and one is the opposite of the other, i.e., the gas piston groove increases in pitch during its power stroke while the hydraulic piston groove decreases. Any number of piston assembly sets may be used to obtain desired hydraulic horsepower

    Historical development of noise exposure metrics

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    Some of the historical events that led to the introduction of night penalties are reported with emphasis on what happens with different kinds of day/night operations when night pentalties are employed. These effects are considered in terms of the difference between a nighttime weighting cumulative measure of noise exposure verses simply not using any night weighting at all, in decibles

    Thin plate buckling mitigation and reduction challenges for naval ships

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    Thin plate buckling or distortion on ship structures is an ongoing issue for shipbuilders. It has been identified that a significant number of factors can be put in place based on prior knowledge and good practice. Additionally, research work aimed at reducing thin plate distortion has been relatively prolific, particularly in the area of simulation modelling. However, the uptake in the research findings by industry has been relatively low. A number of these findings are discussed and their application considered. For any further reductions in thin plate distortion to be generated there is a clear need for better interaction between the research institutes and the industry

    Rigid Singularity Theorem in Globally Hyperbolic Spacetimes

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    We show the rigid singularity theorem, that is, a globally hyperbolic spacetime satisfying the strong energy condition and containing past trapped sets, either is timelike geodesically incomplete or splits isometrically as space ×\times time. This result is related to Yau's Lorentzian splitting conjecture.Comment: 3 pages, uses revtex.sty, to appear in Physical Review

    Nuclear waste disposal in space

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    Work on nuclear waste disposal in space conducted by the George C. Marshall Space Flight Center, National Aeronautics and Space Administration, and contractors are reported. From the aggregate studies, it is concluded that space disposal of nuclear waste is technically feasible

    Undergraduate perceptions of value: degree skills and career skills

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    Recent data suggests that of the UK students graduating with a degree in chemistry in 2015, only 18.9% continued to employment as ‘Science Professionals’. While this shows the wide range of employment that is available for chemistry graduates, it also highlights the need for them to have relevant transferable skills, rather than just the well-developed, subject-specific knowledge that they would be expected to possess. In 2010 Hanson and Overton published a study on the degree skills valued by UK graduates who had found employment and then reflected on the most useful aspects of the degree course. The new investigation reported here expands on this previous work by evaluating the perceived value of these skills by chemistry undergraduate students (years 1, 2, 3) along with their planned occupation after graduation. The results of the skills questionnaire are discussed, along with a survey of the main skills that the students wished to gain by participating in a new extra-curricular module specifically designed to enhance career skills, and the activities designed to develop those skills

    Dual exchange rates : theory, insulation properties and the South African experience

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    Includes bibliographies.Dual exchange rate regimes are not a phenomenon peculiar only to South Africa. In the past they have been implemented by the BLEU, France, Italy and the Netherlands in one form or another. More recently, multiple exchange regimes have been adopted by other developing countries such as Mexico, Brazil, Venezuela and Argentina. The rationale for imposing a two- or multi-tier exchange regime is to protect the balance of payments from volatile short-term capital flows due to political and economic uncertainty inherent in developing economies. The focus of this paper is on the insulation properties of dual market systems against foreign shocks. These shocks may take the form of foreign interest rate increases or increases in foreign perceptions of risk. An implication of these insulation properties is that the monetary authorities are able to pursue a monetary policy independent of external constraints
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