Dr Sam Evans

© 2018 It is well known that wind turbine blades are fatigue critical, with much literature and methodologies available for assessing fatigue loading of large wind turbine blades. Little research effort has been directed at assessing the fatigue life of small wind turbines which operate at higher rotational speeds and are subject to highly unsteady aerodynamic loading. In this paper the simplified load model proposed in IEC 61400.2 is used to determine the fatigue life of a small 5 kW wind turbine blade. This estimated life is compared to that determined from both measured operational data and aeroelastic simulations. Fatigue life was estimated by the standard at 0.09 years, compared to 9.18 years from field measurements and 3.26 years found via aeroelastic simulations. All methods fell below the 20 year design life, with the standard over-conservative by a factor of 102 and 36 for measurements and simulations respectively. To the best of the authors¿ knowledge these three fatigue methods specified in the standard have not been quantitatively compared and assessed for small wind turbines. Results are of importance to small wind turbine developers as they seek best practice for determining blade fatigue life. Shortcomings of the IEC methodology are detailed and discussed.

© 2018 The Author(s) Published by the Royal Society. All rights reserved. Three adaptive hypotheses have been forwarded to explain the distinctive Neanderthal face: (i) an improved ability to accommodate high anterior bite forces, (ii) more effective conditioning of cold and/or dry air and, (iii) adaptation to facilitate greater ventilatory demands. We test these hypotheses using three-dimensional models of Neanderthals, modern humans, and a close outgroup (Homo heidelbergensis), applying finiteelement analysis (FEA) and computational fluid dynamics (CFD). This is the most comprehensive application of either approach applied to date and the first to include both. FEA reveals few differences between H. heidelbergensis, modern humans, and Neanderthals in their capacities to sustain high anterior tooth loadings. CFD shows that the nasal cavities of Neanderthals and especially modern humans condition air more efficiently than does that of H. heidelbergensis, suggesting that both evolved to better withstand cold and/or dry climates than less derived Homo. We further find that Neanderthals could move considerably more air through the nasal pathway than could H. heidelbergensis or modern humans, consistent with the propositions that, relative to our outgroup Homo, Neanderthal facial morphology evolved to reflect improved capacities to better condition cold, dry air, and, to move greater air volumes in response to higher energetic requirements.