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  • 1
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    How birds direct impulse to minimize the energetic cost of foraging flight (2017)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2017-05-18
    Description: Birds frequently hop and fly between tree branches to forage. To determine the mechanical energy trade-offs of their bimodal locomotion, we rewarded four Pacific parrotlets with a seed for flying voluntarily between instrumented perches inside a new aerodynamic force platform. By integrating direct measurements of both leg and wing forces with kinematics in a bimodal long jump and flight model, we discovered that parrotlets direct their leg impulse to minimize the mechanical energy needed to forage over different distances and inclinations. The bimodal locomotion model further shows how even a small lift contribution from a single proto-wingbeat would have significantly lengthened the long jump of foraging arboreal dinosaurs. These avian bimodal locomotion strategies can also help robots traverse cluttered environments more effectively.
    Electronic ISSN: 2375-2548
    Topics: Natural Sciences in General
    Published by American Association for the Advancement of Science (AAAS)
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  • 2
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    Physiology. Turning on a dime (2004)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2004-12-14
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Muller, Ulrike K -- Lentink, David -- New York, N.Y. -- Science. 2004 Dec 10;306(5703):1899-900.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Experimental Zoology, Wageningen University, the Netherlands. ulrike.muller@wur.nl〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/15591191" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Biomechanical Phenomena ; Birds/anatomy & histology/*physiology ; *Flight, Animal ; Models, Anatomic ; Wings, Animal/anatomy & histology/*physiology
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 3
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    Biomimetics: Flying like a fly (2013)
    Nature Publishing Group (NPG)
    Details
    Publication Date: 2013-06-14
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Lentink, David -- England -- Nature. 2013 Jun 20;498(7454):306-7. doi: 10.1038/nature12258. Epub 2013 Jun 12.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/23760475" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Biomimetics/*instrumentation ; Diptera/anatomy & histology/*physiology ; *Flight, Animal ; Robotics/*instrumentation
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Published by Nature Publishing Group (NPG)
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  • 4
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    Leading-edge vortices elevate lift of autorotating plant seeds (2009)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2009-06-13
    Description: As they descend, the autorotating seeds of maples and some other trees generate unexpectedly high lift, but how they attain this elevated performance is unknown. To elucidate the mechanisms responsible, we measured the three-dimensional flow around dynamically scaled models of maple and hornbeam seeds. Our results indicate that these seeds attain high lift by generating a stable leading-edge vortex (LEV) as they descend. The compact LEV, which we verified on real specimens, allows maple seeds to remain in the air more effectively than do a variety of nonautorotating seeds. LEVs also explain the high lift generated by hovering insects, bats, and possibly birds, suggesting that the use of LEVs represents a convergent aerodynamic solution in the evolution of flight performance in both animals and plants.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Lentink, D -- Dickson, W B -- van Leeuwen, J L -- Dickinson, M H -- New York, N.Y. -- Science. 2009 Jun 12;324(5933):1438-40. doi: 10.1126/science.1174196.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Experimental Zoology Group, Wageningen University, 6709 PG Wageningen, Netherlands. david.lentink@wur.nl〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/19520959" target="_blank"〉PubMed〈/a〉
    Keywords: *Acer ; *Betulaceae ; Biomechanical Phenomena ; Models, Anatomic ; *Movement ; Rotation ; Seeds/anatomy & histology/*physiology
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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  • 5
    Electronic Resource
    Electronic Resource
    How swifts control their glide performance with morphing wings (2007)
    [s.l.] : Nature Publishing Group
    Nature 446 (2007), S. 1082-1085 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Gliding birds continually change the shape and size of their wings, presumably to exploit the profound effect of wing morphology on aerodynamic performance. That birds should adjust wing sweep to suit glide speed has been predicted qualitatively by analytical glide models, which extrapolated ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/nature05733
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    Paper (German National Licenses)
    Fulltext
  • 6
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    How swifts control their glide performance with morphing wings (2007)
    Springer Nature
    Details
    Publication Date: 2007-04-01
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Published by Springer Nature
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  • 7
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    Biomechanics of hover performance in Neotropical hummingbirds versus bats (2018)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 2018-09-27
    Description: Hummingbirds and nectar bats are the only vertebrates that are specialized for hovering in front of flowers to forage nectar. How their aerodynamic performance compares is, however, unclear. To hover, hummingbirds consistently generate about a quarter of the vertical aerodynamic force required to support their body weight during the upstroke. In contrast, generalist birds in slow hovering flight generate little upstroke weight support. We report that nectar bats also generate elevated weight support during the upstroke compared to generalist bats. Comparing 20 Neotropical species, we show how nectarivorous birds and bats converged on this ability by inverting their respective feathered and membrane wings more than species with other diets. However, while hummingbirds converged on an efficient horizontal wingbeat to mostly generate lift, bats rely on lift and drag during the downstroke to fully support their body weight. Furthermore, whereas the ability of nectar bats to aerodynamically support their body weight during the upstroke is elevated, it is much smaller than that of hummingbirds. Bats compensate by generating more aerodynamic weight support during their extended downstroke. Although, in principle, it requires more aerodynamic power to hover using this method, bats have adapted by evolving much larger wings for their body weight. Therefore, the net aerodynamic induced power required to hover is similar among hummingbirds and bats per unit body mass. This mechanistic insight into how feathered wings and membrane wings ultimately require similar aerodynamic power to hover may inform analogous design trade-offs in aerial robots.
    Electronic ISSN: 2375-2548
    Topics: Natural Sciences in General
    Published by American Association for the Advancement of Science (AAAS)
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  • 8
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    A new low-turbulence wind tunnel for animal and small vehicle flight experiments (2017)
    Royal Society
    Details
    Publication Date: 2017-03-30
    Description: Our understanding of animal flight benefits greatly from specialized wind tunnels designed for flying animals. Existing facilities can simulate laminar flow during straight, ascending and descending flight, as well as at different altitudes. However, the atmosphere in which animals fly is even more complex. Flow can be laminar and quiet at high altitudes but highly turbulent near the ground, and gusts can rapidly change wind speed. To study flight in both laminar and turbulent environments, a multi-purpose wind tunnel for studying animal and small vehicle flight was built at Stanford University. The tunnel is closed-circuit and can produce airspeeds up to 50 m s –1 in a rectangular test section that is 1.0 m wide, 0.82 m tall and 1.73 m long. Seamless honeycomb and screens in the airline together with a carefully designed contraction reduce centreline turbulence intensities to less than or equal to 0.030% at all operating speeds. A large diameter fan and specialized acoustic treatment allow the tunnel to operate at low noise levels of 76.4 dB at 20 m s –1 . To simulate high turbulence, an active turbulence grid can increase turbulence intensities up to 45%. Finally, an open jet configuration enables stereo high-speed fluoroscopy for studying musculoskeletal control in turbulent flow.
    Keywords: mechanical engineering, biomechanics, biomimetics
    Electronic ISSN: 2054-5703
    Topics: Natural Sciences in General
    Published by Royal Society
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  • 9
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    Structural Analysis of a Dragonfly Wing (2010)
    Springer
    Details
    Publication Date: 2010-10-26
    Print ISSN: 0014-4851
    Electronic ISSN: 1741-2765
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Springer
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  • 10
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    Influence of wing kinematics on aerodynamic performance in hovering insect flight (2007)
    Cambridge University Press
    Details
    Publication Date: 2007-12-14
    Description: The influence of different wing kinematic models on the aerodynamic performance of a hovering insect is investigated by means of two-dimensional time-dependent Navier-Stokes simulations. For this, simplified models are compared with averaged representations of the hovering fruit fly wing kinematics. With increasing complexity, a harmonic model, a Robofly model and two more-realistic fruit fly models are considered, all dynamically scaled at Re = 110. To facilitate the comparison, the parameters of the models were selected such that their mean quasi-steady lift coefficients were matched. Details of the vortex dynamics, as well as the resulting lift and drag forces, were studied. The simulation results reveal that the fruit fly wing kinematics result in forces that differ significantly from those resulting from the simplified wing kinematic models. In addition, light is shed on the effect of different characteristic features of the insect wing motion. The angle of attack variation used by fruit flies increases aerodynamic performance, whereas the deviation is probably used for levelling the forces over the cycle. © 2008 Cambridge University Press.
    Print ISSN: 0022-1120
    Electronic ISSN: 1469-7645
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Published by Cambridge University Press
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