1,991 research outputs found

    The Potentional of Recovered Vegetable Oil and Tallow as Vehicle Fuels

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    End of Project ReportThe use of recovered vegetable oil (RVO) and tallow as vehicle fuels was investigated. Two options were considered; use in unprocessed form in specially adapted engines, and the production of biodiesel for use in unmodified engines. Two vehicles were modified to allow the use of RVO as fuel. Their performance in terms of power and fuel economy was acceptable, but fuel filter blockage problems would need to be resolved and long-term effects on engine life investigated before this approach could be recommended. Tallow with high free-fatty-acid content was esterified by a two-stage process that could be used in a simple plant and produce biodiesel of reasonable quality. High ester yields were obtained in laboratory and pilot-scale trials. Problems of layer separation remain to be resolved, and the process needs to be streamlined to allow a high throughput to be achieved. In comparing the costs of these fuels with each other and with mineral diesel, allowance must be made for any differences in fuel economy and for the cost of engine conversion kits. Including these items, the use of RVO in a converted engine would have a slightly lower cost than its use as biodiesel. Biodiesel from tallow is likely to be more expensive than from RVO if either ester yield or plant capacity is significantly reduced

    Cost reduction in bio-diesel production.

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    End of Project ReportAs part of a programme to assess bio-diesel production from low-cost materials, the availability of waste oils and fats in Ireland and the EU was assessed, and the behaviour of their esters in vehicles was measured. The utilisation of beef tallow from BSE risk organisms was given special attention. Esterification of high-FFA tallow required the use of excess methanol and base catalyst. Acidification, followed by glycerol separation and secondary acid-catalysed esterification, brought ester yields up to acceptable levels. The high melting point of the ester restricted its use in vehicles to low proportions in mixes with mineral diesel. Fuels made up from low-cost esters behaved well in vehicle trials, even where there was a high level of dilution of the engine oil. The only problems arose from inadequate low-temperature properties and from suspended solids in the tallow ester. Within the EU, there are sufficient waste oils and fats available to greatly increase bio-diesel production. In Ireland, there is sufficient for a small production unit

    Field Measurements of Penetrator Seismic Coupling in Sediments and Volcanic Rocks

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    Field experiments were conducted to determine how well a seismometer installed using a penetrator would be coupled to the ground. A dry-lake bed and a lava bed were chosen as test sites to represent geological environments of two widely different material properties. At each site, two half-scale penetrators were fired into the ground, a three-component geophone assembly was mounted to the aft end of each penetrator, and dummy penetrators were at various distances to generate seismic signals. These signals were detected by the penetrator-mounted geophone assembly and by a reference geophone assembly buried or anchored to surface rock and 1-m from the penetrator. The recorded signals were digitized, and cross-spectral analyses were performed to compare the observed signals in terms of power spectral density ratio, coherence, and phase difference. The analyses indicate that seismometers deployed by penetrators will be as well coupled to the ground as are seismometers installed by conventional methods for the frequency range of interest in earthquake seismology

    The Logarithmic Triviality of Compact QED Coupled to a Four Fermi Interaction

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    This is the completion of an exploratory study of Compact lattice Quantum Electrodynamics with a weak four-fermi interaction and four species of massless fermions. In this formulation of Quantum Electrodynamics massless fermions can be simulated directly and Finite Size Scaling analyses can be performed at the theory's chiral symmetry breaking critical point. High statistics simulations on lattices ranging from 848^4 to 24424^4 yield the equation of state, critical indices, scaling functions and cumulants. The measurements are well fit with the orthodox hypothesis that the theory is logarithmically trivial and its continuum limit suffers from Landau's zero charge problem.Comment: 27 pages, 15 figues and 10 table

    Family memories in the home: contrasting physical and digital mementos

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    We carried out fieldwork to characterise and compare physical and digital mementos in the home. Physical mementos are highly valued, heterogeneous and support different types of recollection. Contrary to expectations, we found physical mementos are not purely representational, and can involve appropriating common objects and more idiosyncratic forms. In contrast, digital mementos were initially perceived as less valuable, although participants later reconsidered this. Digital mementos were somewhat limited in function and expression, largely involving representational photos and videos, and infrequently accessed. We explain these digital limitations and conclude with design guidelines for digital mementos, including better techniques for accessing and integrating these into everyday life, allowing them to acquire the symbolic associations and lasting value that characterise their physical counterparts

    Using failed supernovae to constrain the Galactic r-process element production

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    Rapid neutron capture process (r-process) elements have been detected in a large fraction of metal-poor halo stars, with abundances relative to iron (Fe) that vary by over two orders of magnitude. This scatter is reduced to less than a factor of 3 in younger Galactic disc stars. The large scatter of r-process elements in the early Galaxy suggests that the r-process is made by rare events, like compact binary mergers and rare sub-classes of supernovae. Although being rare, neutron star mergers alone have difficulties to explain the observed enhancement of r-process elements in the lowest metallicity stars compared to Fe. The supernovae producing the two neutron stars already provide a substantial Fe abundance where the r-process ejecta from the merger would be injected. In this work we investigate another complementary scenario, where the r-process occurs in neutron star-black hole mergers in addition to neutron star mergers. Neutron star-black hole mergers would eject similar amounts of r-process matter as neutron star mergers, but only the neutron star progenitor would have produced Fe. Furthermore, a reduced efficiency of Fe production from single stars significantly alters the age-metallicity relation, which shifts the onset of r-process production to lower metallicities. We use the high-resolution [(20 pc)3/cell] inhomogeneous chemical evolution tool `ICE' to study the outcomes of these effects. In our simulations, an adequate combination of neutron star mergers and neutron star-black hole mergers qualitatively reproduces the observed r-process abundances in the Galaxy

    Quantitative analysis of the morphological changes of the pubic symphyseal face and the auricular surface and implications for age at death estimation

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    YesAge estimation methods are often based on the age-related morphological changes of the auricular surface and the pubic bone. In this study, a mathematical approach to quantify these changes has been tested analyzing the curvature variation on 3D models from CT and laser scans. The sample consisted of the 24 Suchey–Brooks (SB) pubic bone casts, 19 auricular surfaces from the Buckberry and Chamberlain (BC) “recording kit” and 98 pelvic bones from the Terry Collection (Smithsonian Institution). Strong and moderate correlations between phases and curvature were found in SB casts (ρ 0.60–0.93) and BC “recording kit” (ρ 0.47–0.75), moderate and weak correlations in the Terry Collection bones (pubic bones: ρ 0.29–0.51, auricular surfaces: ρ 0.33–0.50) but associated with large individual variability and overlap of curvature values between adjacent decades. The new procedure, requiring no expert judgment from the operator, achieved similar correlations that can be found in the classic methods

    Microbiology and atmospheric processes: Biological, physical and chemical characterization of aerosol particles

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    The interest in bioaerosols has traditionally been linked to health hazards for humans, animals and plants. However, several components of bioaerosols exhibit physical properties of great significance for cloud processes, such as ice nucleation and cloud condensation. To gain a better understanding of their influence on climate, it is therefore important to determine the composition, concentration, seasonal fluctuation, regional diversity and evolution of bioaerosols. In this paper, we will review briefly the existing techniques for detection, quantification, physical and chemical analysis of biological particles, attempting to bridge physical, chemical and biological methods for analysis of biological particles and integrate them with aerosol sampling techniques. We will also explore some emerging spectroscopy techniques for bulk and single-particle analysis that have potential for in-situ physical and chemical analysis. Lastly, we will outline open questions and further desired capabilities (e. g., in-situ, sensitive, both broad and selective, on-line, time-resolved, rapid, versatile, cost-effective techniques) required prior to comprehensive understanding of chemical and physical characterization of bioaerosols

    Direct Questioning of Genital Symptoms Increasing Opportunities for Identifying and Treating Sexually Transmitted Infections in Primary Health-care settings

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    We investigated the validity of self-reporting of genital symptoms amongst rural women attending primary health care clinics in rural KwaZulu-Natal. Random samples of 226 women were interviewed to measure self-reporting (unprompted), prompted and pelvic examination findings of genital symptoms. Against the presence of any STI self- reporting (unprompted) of symptoms had a sensitivity of 46.1%, specificity of 64.7%, positive predictive value (PPV) of 80.0% and negative predictive value (NPV) of 28.0% compared to prompted symptoms which had a sensitivity of 78.5%, specificity of 52.9%, PPV of 80.4% and NPV of 50.0%. The agreement between self- reporting (unprompted) and prompted symptoms was 0.54 (Kappa statistic). Our results suggest that in rural areas, by prompting women with a simple set of questions, the identification and treatment of STIs in this population would be enhanced, leading to better reproductive health outcomes including reduction of risk of infection with HIV. African Journal of Reproductive Health Vol. 10 (2) 2006: pp. 105-11
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