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Burin Gumjudpai - One of the best experts on this subject based on the ideXlab platform.
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slow Roll Acceleration the big rip and the wentzel kramers brillouin approximation in the non linear schrodinger type formulation of scalar field cosmology
Journal of Cosmology and Astroparticle Physics, 2008Co-Authors: Burin GumjudpaiAbstract:Aspects of the non-linear Schrodinger (NLS) type of formulation of scalar (phantom) field cosmology for slow-Roll, Acceleration, the Wentzel–Kramers–Brillouin (WKB) approximation and the big rip singularity are presented. Slow-Roll parameters for the curvature and barotropic density terms are introduced. We re-express all slow-Roll parameters, slow-Roll conditions and the Acceleration condition in NLS form. The WKB approximation in the NLS formulation is also discussed while simplifying to the linear case. Most of the Schrodinger potentials in the NLS formulation are very slowly varying; hence the WKB approximation is valid in some ranges. In the NLS form of the big rip singularity, two quantities are infinite instead of three. We also found that approaching the big rip, , which is the same as the effective phantom equation of state in the flat case.
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slow Roll Acceleration the big rip and wkb approximation in nls type formulation of scalar field cosmology
arXiv: General Relativity and Quantum Cosmology, 2008Co-Authors: Burin GumjudpaiAbstract:Aspects of non-linear Schr\"{o}dinger-type (NLS) formulation of scalar (phantom) field cosmology on slow-Roll, Acceleration, WKB approximation and Big Rip singularity are presented. Slow-Roll parameters for the curvature and barotropic density terms are introduced. We reexpress all slow-Roll parameters, slow-Roll conditions and Acceleration condition in NLS form. WKB approximation in the NLS formulation is also discussed when simplifying to linear case. Most of the Schr\"{o}dinger potentials in NLS formulation are very slowly-varying, hence WKB approximation is valid in the ranges. In the NLS form of Big Rip singularity, two quantities are infinity in stead of three. We also found that approaching the Big Rip, $w_{\rm eff}\to -1 + {2}/{3q}$, $(q<0)$ which is the same as effective phantom equation of state in the flat case.
Ulla M. Norberg - One of the best experts on this subject based on the ideXlab platform.
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Moments of Inertia of Bat Wings and Body
The Journal of Experimental Biology, 1991Co-Authors: Mikael Thollesson, Ulla M. NorbergAbstract:The moments of inertia of the wings about the shoulder joint and about the Roll axis were estimated in eight species of bats, using strip analysis. The moment of inertia of the bat9s trunk about the Roll axis was estimated by assuming the body and head to be ellipsoids. The slopes of the regressions of moment of inertia of one wing about the shoulder joint ( J w ) versus body mass ( m tot ), wing span ( b ) and wing area (S) were as expected for geometrically similar animals of different size. The exponent for J w versus body mass in bats deviates from that found for birds, while the exponent for J w versus wing span does not. A multiple regression was used to show that J w may be estimated by: J w = 4.49 × 10 −3 m tot 0.53 b 2.15 S 0.65 . The mean value of the moment of inertia originating from the trunk is 7 % of the bat9s total moment of inertia (of wings and body combined) about the Roll axis. The mass of one wing ( m w ) was plotted against body mass for the eight bat species, which gives: m w = 0.112 m tot 1 11 . The slope for our bats, 1.11, is similar to that obtained for birds, 1.10. Adaptations to reduce the moments of inertia may be more important for increasing a bat9s flight agility (Roll Acceleration) than for decreasing the total mechanical power required to fly. The influences of wing moment of inertia and wing shape on manoeuvrability and agility are discussed.
Mikael Thollesson - One of the best experts on this subject based on the ideXlab platform.
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Moments of Inertia of Bat Wings and Body
The Journal of Experimental Biology, 1991Co-Authors: Mikael Thollesson, Ulla M. NorbergAbstract:The moments of inertia of the wings about the shoulder joint and about the Roll axis were estimated in eight species of bats, using strip analysis. The moment of inertia of the bat9s trunk about the Roll axis was estimated by assuming the body and head to be ellipsoids. The slopes of the regressions of moment of inertia of one wing about the shoulder joint ( J w ) versus body mass ( m tot ), wing span ( b ) and wing area (S) were as expected for geometrically similar animals of different size. The exponent for J w versus body mass in bats deviates from that found for birds, while the exponent for J w versus wing span does not. A multiple regression was used to show that J w may be estimated by: J w = 4.49 × 10 −3 m tot 0.53 b 2.15 S 0.65 . The mean value of the moment of inertia originating from the trunk is 7 % of the bat9s total moment of inertia (of wings and body combined) about the Roll axis. The mass of one wing ( m w ) was plotted against body mass for the eight bat species, which gives: m w = 0.112 m tot 1 11 . The slope for our bats, 1.11, is similar to that obtained for birds, 1.10. Adaptations to reduce the moments of inertia may be more important for increasing a bat9s flight agility (Roll Acceleration) than for decreasing the total mechanical power required to fly. The influences of wing moment of inertia and wing shape on manoeuvrability and agility are discussed.
Ck Hemelrijk - One of the best experts on this subject based on the ideXlab platform.
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Sexual size dimorphism, prey morphology and catch success in relation to flight mechanics in the peregrine falcon: a simulation study
'Wiley', 2019Co-Authors: Mills R, Gk Taylor, Ck HemelrijkAbstract:In common with many other raptors, female peregrine falcons Falco peregrinus are about 50% heavier than males. Their sexual dimorphism is thought to allow breeding pairs to exploit a wider range of prey through a division of labor: the male being able to catch more maneuverable prey species; the female capable of carrying larger ones. Given the difficulty of assessing the catch success and load carrying capacity of both sexes of falcon in the field, we here adopt a novel approach to test the division‐of‐labor theory by using a detailed physics‐based flight simulator of birds. We study attacks by male and female peregrines on prey species ranging from small passerines to large ducks, testing how catch success relates to the flight performance of predator and prey. Males prove to be better than females at catching highly maneuverable prey in level flight, but the catch success of both sexes improves and becomes more similar when diving, because of the higher aerodynamic forces that are available to both sexes for maneuvering in high‐speed flight. The higher maximum Roll Acceleration of the male peregrine explains its edge over the female in catching maneuverable prey in level flight. Overall, catch success is more strongly influenced by the differences in maneuverability that exist between different species of prey than between the different sexes of falcon. On the other hand, the female can carry up to 50% greater loads than the male. More generally, our detailed simulation approach highlights the importance of several previously overlooked features of attack and escape. In particular, we find that it is not the prey's instantaneous maximum centripetal Acceleration but the prey's ability to sustain a high centripetal Acceleration for an extended period of time that is the primary driver of the variation in catch success across species
Hemelrijk, Charlotte K. - One of the best experts on this subject based on the ideXlab platform.
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Data from: Sexual size dimorphism, prey morphology, and catch success in relation to flight mechanics in the Peregrine Falcon: a simulation study
2019Co-Authors: Mills Robin, Taylor, Graham K., Hemelrijk, Charlotte K.Abstract:In common with many other raptors, female Peregrine Falcons Falco peregrinus are about 50% heavier than males. Their sexual dimorphism is thought to allow breeding pairs to exploit a wider range of prey through a division of labor: the male being able to catch more maneuverable prey species; the female capable of carrying larger ones. Given the difficulty of assessing the catch success and load carrying capacity of both sexes of falcon in the field, we here adopt a novel approach to test the division‐of‐labor theory by using a detailed physics‐based flight simulator of birds. We study attacks by male and female Peregrine Falcons on prey species ranging from small passerines to large ducks, testing how catch success relates to the flight performance of predator and prey. Males prove to be better than females at catching highly maneuverable prey in level flight, but the catch success of both sexes improves and becomes more similar when diving, because of the higher aerodynamic forces that are available to both sexes for maneuvering in high‐speed flight. The higher maximum Roll Acceleration of the male Peregrine Falcon explains its edge over the female in catching maneuverable prey in level flight. Overall, catch success is more strongly influenced by the differences in maneuverability that exist between different species of prey than between the different sexes of falcon. On the other hand, the female can carry up to 50% greater loads than the male. More generally, our detailed simulation approach highlights the importance of several previously overlooked features of attack and escape. In particular, we find that it is not the prey's instantaneous maximum centripetal Acceleration but the prey's ability to sustain a high centripetal Acceleration for an extended period of time that is the primary driver of the variation in catch success across species
