9,740 research outputs found

    A-STAR: The All-Sky Transient Astrophysics Reporter

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    The small mission A-STAR (All-Sky Transient Astrophysics Reporter) aims to locate the X-ray counterparts to ALIGO and other gravitational wave detector sources, to study the poorly-understood low luminosity gamma-ray bursts, and to find a wide variety of transient high-energy source types, A-STAR will survey the entire available sky twice per 24 hours. The payload consists of a coded mask instrument, Owl, operating in the novel low energy band 4-150 keV, and a sensitive wide-field focussing soft X-ray instrument, Lobster, working over 0.15-5 keV. A-STAR will trigger on ~100 GRBs/yr, rapidly distributing their locations.Comment: Accepted for the European Astronomical Society Publications Series: Proceedings of the Fall 2012 Gamma-Ray Burst Symposium held in Marbella, Spain, 8-12 Oct 201

    Use of Water by Piglets in the First Days after Birth

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    Use of drinking water was determined for 51 litters of piglets by weighing and refilling a water dispenser each day for the first 4 d after farrowing. Measures of spillage, evaporation, and piglet drinking behavior indicated that most disappearance of water represented actual drinking by the piglets. Water use varied greatly among litters with an average of 46 g d‒1 per piglet over the 4 d, and a range of negligible use to about 200 g d‒1. Water use, especially on day 2, was correlated negatively with the average weight gain of the litter during the first 2 d (r = ‒0.45, P \u3c 0.001). Litters that lost weight or gained very little on days 1 and 2 showed a pronounced peak of water use on day 2 (averaging about 100 g d‒1 per piglet), with declining use on days 3 and 4. In contrast, litters with high initial weight gains drank little water on days 1 and 2 but showed a steady increase in water use to day 4. The results suggest that piglets will drink appreciable amounts of water on the first days after birth especially if their milk intake is limited. We speculate that under these circumstances water intake may help to prevent dehydration and promote survival of piglets with low early milk intake

    An experimental investigation of yarn tension in simulated ring spinning

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    Yarn tension is a key factor that affects the efficiency of a ring spinning system. In this paper, a specially constructed rig, which can rotate a yarn at a high speed without inserting any real twist into the yarn, was used to simulate a ring spinning process. Yarn tension was measured at the guide-eye during the simulated spinning of different yarns at various balloon heights and with varying yarn length in the balloon. The effect of balloon shape, yarn hairiness and thickness, and yarn rotating speed, on the measured yarn tension, was examined. The results indicate that the collapse of balloon shape from single loop to double loop, or from double loop to triple etc, lead to sudden reduction in yarn tension. Under otherwise identical conditions, a longer length of yarn in the balloon gives a lower yarn tension at the guide-eye. In addition, thicker yarns and/or more hairy yarns generate a higher tension in the yarn, due to the increased air drag acting on the thicker or more hairy yarns

    Evolution of population with sexual and asexual reproduction in changing environment

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    Using a lattice model based on Monte Carlo simulations, we study the role of the reproduction pattern on the fate of an evolving population. Each individual is under the selection pressure from the environment and random mutations. The habitat ("climate") is changing periodically. Evolutions of populations following two reproduction patterns are compared, asexual and sexual. We show, via Monte Carlo simulations, that sexual reproduction by keeping more diversified populations gives them better chances to adapt themselves to the changing environment. However, in order to obtain a greater chance to mate, the birth rate should be high. In the case of low birth rate and high mutation probability there is a preference for the asexual reproduction.Comment: 11 pages including figs., for Int. J. Mod. Phys. C 15, issue 2 (2004

    The effect of yarn hairiness on air drag in ring spinning

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    Air drag on yarn and package surfaces affects yarn tension, which in turn affects energy consumption and ends-down in ring spinning. This study investigated the effects of yarn hairiness on air drag in ring spinning. Theoretical models of skin friction coefficient on the surface of rotating yarn packages were developed. The predicted results were verified with experimental data obtained from cotton and wool yarns. The results show that hairiness increases the air drag by about one-quarter and one-third for the rotating cotton and wool yarn packages, respectively. In addition, yarn hairiness increases the air drag by about one-tenth on a ballooning cotton yarn.<br /

    The Kuiper Belt Luminosity Function from m(R)=21 to 26

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    We have performed an ecliptic imaging survey of the Kuiper belt with our deepest and widest field achieving a limiting flux of m(g') = 26.4, with a sky coverage of 3.0 square-degrees. This is the largest coverage of any other Kuiper belt survey to this depth. We detect 72 objects, two of which have been previously observed. We have improved the Bayesian maximum likelihood fitting technique presented in Gladman et al. (1998) to account for calibration and sky density variations and have used this to determine the luminosity function of the Kuiper belt. Combining our detections with previous surveys, we find the luminosity function is well represented by a single power-law with slope alpha = 0.65 +/- 0.05 and an on ecliptic sky density of 1 object per square-degree brighter than m(R)=23.42 +/- 0.13. Assuming constant albedos, this slope suggests a differential size-distribution slope of 4.25 +/- 0.25, which is steeper than the Dohnanyi slope of 3.5 expected if the belt is in a state of collisional equilibrium. We find no evidence for a roll-over or knee in the luminosity function and reject such models brightward of m(R) ~ 24.6.Comment: 50 Pages, 8 Figure

    PLM in design and engineering education: International perspectives

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    Technological advances in the last decade have influenced changes in the design and engineering industries on a global scale. Lean and collaborative product development are approaches increasingly adopted by the industry and seen as the core of product lifecycle management. These trends have created the need for new skilled professionals, and universities should adapt their curricula in response. There is an increased need for academia to work with industry in order to meet these challenges. This article reports on the Parametric Technology Corporation Academic Research Symposium held in April 2011. The topics were centred around understanding the essence of product lifecycle management and its impact on design and engineering education. Furthermore, examples of implementing product lifecycle management and collaborative practices in higher education were presented from the United States and France. This article concludes with a discussion of the recommendations made at the symposium for the future development and support of key skills across university curricula
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