Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 30 for “"Perching"”.
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Supermaneuverable perching
… capable of executing a highly dynamic bird-like perching maneuver to land on a power-line by exploiting pressure drag on its stalled wings and tail. We present a feedback controller capable of stabilizing the maneuver over a wide range of flight speeds and quantify its robustness to wind-gust …
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Perching with fixed wings
… fluid dynamics on the response of the vehicle. Perching is representative of a large class of control problems for aerobatics that requires and agile and robust control system with the capability of planning well into the future. Our experimental paradigm along with the simplicity of the problem …
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Powerline perching with a fixed-wing UAV
… for long missions. Recent advances in fixed-wing perching have made it possible to consider a new solution to this problem - landing on a powerline to recharge. Furthermore, because a current carrying conductor generates a magnetic field, a unique opportunity exists to use the powerline not just …
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Robust post-stall perching with a fixed-wing UAV
Consider a bird perching on a branch. In the presence of environmental disturbances and complicated fluid flow, the animal exploits post-stall pressure drag to rapidly decelerate and land on a perch with a precision far beyond the capabilities of our best aircraft control systems. In this thesis, I …
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Bistable prestressed spring steel grippers for aerial perching and grasping
… power and range of current drones. Aerial perching can extend the useful flight time of a drone by allowing for passive perching in a location for a desired amount of time. Compliant bistable mechanisms are well-suited for this application because of their adaptability in a wide range of …
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Analysis of High Angle of Attack Maneuvers to Enhance Understanding of the Aerodynamics of Perching
… to study and improve the flight performance of a perching maneuver. Flowfield images and force history data are acquired to investigate the performance of highly unsteady motions experienced during a perching maneuver. The perching motions studied are divided into two first order approximations, a …
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Nature's engineering : a blueprint for efficient aircraft design
… aircraft efficiency are morphing wings and perching. Morphing wings allow airplanes to change the shape of their wings to suit the needs of their mission. Perching is a landing maneuver that uses the nonlinear dynamics of stall to create the drag forces necessary to decelerate the aircraft. …
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Bald eagle habitat use on B. Everett Jordan Lake and Falls Lake, North Carolina
I examined the roosting and perching habitat preferences of a nonbreeding population of bald eagles in North Carolina during 1986 and 1987. I characterized roosting habitat at 2 scales; those of forest stands and individual roost trees. Eagles chose roost areas that were less dense, had less canopy …
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Karstification of the Pennyroyal Plain Behind the Retreating Chester Escarpment: Warren, Simpson & Logan Counties, Kentucky
… and plateau blanket the stream beds thus perching the streams and preventing chemically aggressive water from forming karst solution features in the limestones. The streams farther away from the escarpment are removed from the sediment source and are therefore able to downcut into the …
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Dynamics and control of robotic aircraft with articulated wings
… is very useful for initiating an efficient perching maneuver. It is shown that wing dihedral angles alone can e ffectively regulate sideslip during rapid turns and generate a wide range of equilibrium turn rates while maintaining a constant flight speed and regulating sideslip. We compute …
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Applications of Molecular Switching and Logic
… release their cargo. The intermediate state of perching complexation is also demonstrated. Such switchable second-sphere complexation opens the way to hide or expose the functions of polypyridylRu(II) complexes under arbitrary control. <br/><br/>The overall conclusions of this research in the …
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BISTABLE STRUCTURES ENABLE PASSIVE TRANSITIONS IN MOBILE ROBOTS
… mechanisms on grasping and flying systems. For perching, we show that attaching a linkage to a passive bistable structure augments a gripper’s locking strength, leading to passive grasping with a high strength-to-weight ratio. For aerial reconfiguration, we demonstrate that the energy cost of …
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Movements and home range size of bald eagles from Glacier Bay National Park and Preserve, Alaska: with an analysis of satellite telemetry
… bald eagles were perched 91 % of the time; and perching was the most frequently observed activity (£ < 0.001). Adult eagles perched more often in conifers than cottonwoods, snags, or intertidal debris (£ < 0.001). Perch types selected (£ = 0.473), as well as eagle activity (£ = 0.126) were …
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Lithologic Controls on Karst Groundwater Flow, Lost River Groundwater Basin, Warren County, Kentucky
… 1983) of the St. Louis, which appear to be perching layers to shallow karst groundwater flow. Groundwater may be seen flowing on top of these beds in various cave streams and at swallets and springs throughout the basin.</p> <p> In order to compare the vertical positions of these layers to …
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Behavioral syndromes and their effect on dispersal in Notonecta irrorata
… vegetation use, number of prey consumed, and perching depth). These four traits were correlated along a "boldness gradient" and individuals were sorted into personality types based on where they fell along this bold/passive axis. Bold individuals spent, on average, more time swimming, used …
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Biologically inspired attitude control of robotic systems using center of gravity reallocation
… highly agile maneuvers such as upside-down perching (performed in order to approach roosting position), employ these inertial forces to reallocate the center of gravity of their bodies. The study of these natural species, motivates us to consider the effectiveness of center of gravity …
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Aerodynamic study of a small, ducted VTOL aerial vehicle
The Perching Unmanned Aerial Vehicle (PUAV) is a 9-inch diameter ducted vertical takeoff and landing reconnaissance vehicle with the capability of fast-forward cruise flight. Currently in the development stage, the program is envisaged to yield a man-portable craft that a foot soldier can use to …
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The thermal biology of the growing broiler having access to a means of conductive heat transfer in a hot environment
… both 3 wk and 6 wk of age broilers. Duration of perching bouts and methods of water cooled perch use by broilers were dependent upon ambient temperature, age, height, diameter, and position of perches within the pen. The physiological responses of broilers to perch cooling in a hot ambient …
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Assessment of behaviour and egg production of laying hens kept in cages and floor systems on a commercial farm in South Africa
… on dustbathing, nesting, feather pecking, and perching behaviours, as well as body condition scores. Body weights, egg production, and feed intake were recorded on weekly intervals. Eggs were collected daily between the hours of 8:00 am and 10:00 am in all housing systems to determine egg …
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