976 research outputs found

    Fortran Package for Least Squares Curve Fitting and the Solution of Simultaneous Equations

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    Fortran subroutines for least squares curve fitting and solution of simultaneous equation

    Multidisciplinary Design Optimization of an Extreme Aspect Ration HALE UAV

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    Development of High Altitude Long Endurance (HALE) aircraft systems is part of a vision for a low cost communications/surveillance capability. Applications of a multi payload aircraft operating for extended periods at stratospheric altitudes span military and civil genres and support battlefield operations, communications, atmospheric or agricultural monitoring, surveillance, and other disciplines that may currently require satellite-based infrastructure. The central goal of this research was the development of a multidisciplinary tool for analysis, design, and optimization of HALE UAVs, facilitating the study of a novel configuration concept. Applying design ideas stemming from a unique WWII-era project, a pinned wing HALE aircraft would employ self-supporting wing segments assembled into one overall flying wing. When wrapped in an optimization routine, the integrated design environment shows potential for a 17.3% reduction in weight when wing thickness to chord ratio, aspect ratio, wing loading, and power to weight ratio are included as optimizer-controlled design variables. Investigation of applying the sustained day/night mission requirement and improved technology factors to the design shows that there are potential benefits associated with a segmented or pinned wing. As expected, wing structural weight is reduced, but benefits diminish as higher numbers of wing segments are considered. For an aircraft consisting of six wing segments, a maximum of 14.2% reduction in gross weight over an advanced technology optimal baseline is predicted

    Molecular excitation in the Interstellar Medium: recent advances in collisional, radiative and chemical processes

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    We review the different excitation processes in the interstellar mediumComment: Accepted in Chem. Re

    The Cause of ‘Weak-Link’ Grain Boundary Behaviour in Polycrystalline Bi2Sr2CaCu2O8 and Bi2Sr2Ca2Cu3O10 Superconductors

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    The detrimental effects of grain boundaries have long been considered responsible for the low critical current densities (J_c) in high temperature superconductors. In this paper, we apply the quantitative approach used to identify the cause of the 'weak-link' grain boundary behaviour in YBa2Cu3O7 [1], to the Bi2Sr2CaCu2O8 and Bi2Sr2Ca2Cu3O10 materials that we have fabricated. Magnetic and transport measurements are used to characterise the grain and grain boundary properties of micro- and nanocrystalline material. Magnetisation measurements on all nanocrystalline materials show non-Bean-like behaviour and are consistent with surface pinning. Bi2Sr2CaCu2O8: Our microcrystalline material has very low grain boundary resistivity (ρ_GB), which is similar to that of the grains (ρ_G) such that ρ_GB≈ρ_G=2×〖10〗^(-5) Ωm (assuming a grain boundary thickness (d) of 1 nm) equivalent to an areal resistivity of ρ_G=2×〖10〗^(-14) Ωm^2. The transport J_c values are consistent with well-connected grains and very weak grain boundary pinning. However, unlike low temperature superconductors in which decreasing grain size increases the pinning along the grain boundary channels, any increase in pinning produced by making the grains in our Bi2Sr2CaCu2O8 materials nanocrystalline was completely offset by a decrease in the depairing current density of the grain boundaries caused by their high resistivity. We suggest a different approach to increasing J_c from that used in LTS materials, namely incorporating additional strong grain and grain boundary pinning sites in microcrystalline materials to produce high J_c values. Bi2Sr2Ca2Cu3O10: Both our micro- and nanocrystalline samples have ρ_GB/ρ_G of at least 10^3. This causes strong suppression of J_c across the grain boundaries, which explains the low transport J_c values we find experimentally. Our calculations show that low J_c in untextured polycrystalline Bi2Sr2Ca2Cu3O10 material is to be expected and the significant effort in the community in texturing samples and removing grain boundaries altogether is well-founded

    Current antimicrobial use in farm animals in the Republic of Ireland

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    peer-reviewedAbstract Antimicrobial resistance has been recognised as one of the most difficult challenges facing human and animal health in recent decades. The surveillance of antimicrobial use in animal health plays a major role in dealing with the growing issue of resistance. This paper reviews current data available on antimicrobial use in farmed animals in the Republic of Ireland, including each of the major livestock production sectors; pigs, poultry, dairy, beef and sheep. A systematic literature search was conducted to identify relevant published literature, and ongoing research was identified through the network of authors and searches of each of the research databases of the main agriculture funding bodies in Ireland. The varying quantities and quality of data available across each livestock sector underlines the need for harmonisation of data collection methods. This review highlights the progress that has been made regarding data collection in the intensive production sectors such as pigs and poultry, however, it is clear there are significant knowledge gaps in less intensive industries such as dairy, beef and sheep. To comply with European regulations an antimicrobial data collection system is due to be developed for all food-producing animals in the future, however in the short-term surveillance studies have allowed us to build a picture of current use within the Republic of Ireland. Further studies will allow us to fill current knowledge gaps and build a more comprehensive overview of antimicrobial use in farm animals in Ireland

    Reliability of functional and predictive methods to estimate the hip joint centre in human motion analysis in healthy adults.

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    In human motion analysis predictive or functional methods are used to estimate the location of the hip joint centre (HJC). It has been shown that the Harrington regression equations (HRE) and geometric sphere fit (GSF) method are the most accurate predictive and functional methods, respectively. To date, the comparative reliability of both approaches has not been assessed. The aims of this study were to (1) compare the reliability of the HRE and the GSF methods, (2) analyse the impact of the number of thigh markers used in the GSF method on the reliability, (3) evaluate how alterations to the movements that comprise the functional trials impact HJC estimations using the GSF method, and (4) assess the influence of the initial guess in the GSF method on the HJC estimation. Fourteen healthy adults were tested on two occasions using a three-dimensional motion capturing system. Skin surface marker positions were acquired while participants performed quite stance, perturbed and non-perturbed functional trials, and walking trials. Results showed that the HRE were more reliable in locating the HJC than the GSF method. However, comparison of inter-session hip kinematics during gait did not show any significant difference between the approaches. Different initial guesses in the GSF method did not result in significant differences in the final HJC location. The GSF method was sensitive to the functional trial performance and therefore it is important to standardize the functional trial performance to ensure a repeatable estimate of the HJC when using the GSF method
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