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 52 for “"Gusts"”.
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Lift fluctuations on aerofoils in transverse and steamwise gusts.
… field of flow, The effects df both 'transverse gusts' as considered by Karman and Sears (13) and 1 streamwise gusts' as considered by Horlock (4 0), have been studied. To enable actual lift and pressure fluctuations to be measured a gust tunnel capable of producting both types of gust has been …
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Large Eddy Simulation Of Surface Pressure Fluctuations Generated By Elevated Gusts
Wind gusts cause substantial damage to wind turbines. If these damaging winds could be detected prior to their interaction with the turbine, the turbine rotor can be decoupled from the generator and gearing system to prevent damage during the gust event. This would significantly reduce wind turbine …
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Effect of frontal gusts and stroke deviation in forward flapping flight and deconstructing the aerodynamics of a fruit bat
… flight, at Re=10,000, subjected to frontal gusts. Gusts are a common ecological hazard for flapping fliers, especially in crowded environments. Among the various temporal and spatial scales of gust possible, we look at the phasing and duration of very large spatial scale gusts and their …
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Mitigation of Gust Loads Through Pitching
Wind gusts can cause large loads on aerial vehicles, affecting their controllability and hindering their performance. The negative impact is especially significant for small vehicles, which experience relatively stronger gusts due to their low speeds. This raises the necessity of a control approach …
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Quality control and analysis of an updated wind gust data set in the United States
… set contains more than 17.9 million peak wind gusts, including nearly double the station-years available compared to the data set used in the current ASCE/SEI 7-22 wind hazard maps. A rigorous quality control methodology was implemented using manual inspection of archived Meteorological …
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Unsteady Aerodynamics of Wing–Vortex Gust Encounters
Wind gusts induce severe unsteady loads on low-speed aerodynamic devices, limiting the usability of small, slow-flying aircraft such as drones. Expanding the range of conditions under which these aircraft can safely operate requires control systems that can provide the necessary mitigating actions …
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Vibration control and gust alleviation of highly flexible blended-wing-body aircraft
Suppressing the excitation from gusts that flexible vehicles experience in high-altitude, long-endurance flights is critical to improving their flight performance and maintaining stable flight. Aircraft designed for high-altitude, long-endurance flights tend to be more flexible due to the design …
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Stator loading measurements behind a fan with trailing edge blowing
… the effects of the longitudinal and transverse gusts partially cancel each other in the no blowing case at 50% span. Thus, it is likely that trailing edge blowing disturbs the established balance resulting in an unsteady loading increase even though the wake harmonics are reduced. The flow field …
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Environmental Influences on Tree-driven Karst Bedrock Physical Weathering
… or generate forces on rock in response to wind gusts, these processes have not been investigated in temperate karst regions until now. I monitored forces at the root-rock interface for an American elm and Hackberry tree between September 2019 and May 2020. I used piezoelectric force sensors to …
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Theoretical prediction of counter-rotating propeller noise
… profile which is written as a series of harmonic gusts. The fluctuating pressure distribution on the downstream blades can then be calculated in the high frequency limit. Comparisons are made between measurements and predictions for a counter-rotation propeller and for rotor/stator interaction on …
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Development of a light-weight manipulator system for an omni-directional multi-rotor platform
… position a sensor in environments where wind gusts are present. In addition to its ability to complete disturbance rejection using visual servoing, the manipulator system provides the potential for pick-and-place operations. Physical testing of the prototype verified its ability to detect and …
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MICRO AIR VEHICLE SCALE GUST-WING INTERACTION IN A WIND TUNNEL
… below the tunnel and ducted through its floor. Gusts of up to 40% of the freestream velocity were created. Characterization of the gust generator is shown, and its interaction with a stationary wing at several angles of attack is evaluated. The actuated gust profile is also compared to that of a …
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Linear Parameter Varying Path Following Control of a Small Fixed Wing Unmanned Aerial Vehicle
… environment that included steady winds and gusts, measurement noise, delays, and model uncertainties. The linear controllers designed within were found to be robust to the disturbances and uncertainties in the simulation environment, and had similar or better performance in comparison to a …
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Three-Dimensional Unsteady Hydrodynamics of Tidal Turbines
… to estimate unsteady forces on turbines due to gusts, and by providing new low-order modelling tools for more accurate calculations of these forces. The focus of this thesis is on the assumption of locally two-dimensional (2D) flow used in the majority of turbine loading models. Tidal turbines …
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The sedimentology of diamondiferous deflation deposits within the Sperrgebiet, Namibia
… 50 to 60 km/hour between October and March, and gusts at 80 to 90 km/hour. At these velocities, grains exceeding -1 phi (2 mm) in diameter are commonly entrained into the saltation load above stone pavement surfaces, making this an extremely active aeolian environment.
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Unsteady Aerodynamics of Wing-Gust Encounters
Wind gusts can be highly detrimental to the performance of fixed wing aircraft. At low flight speeds, gusts transverse to the lifting surfaces can cause massive changes to the angle of incidence, fluctuations in lift and drag, and result in flight instability. This may be catastrophic for small …
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Design of an Experimental Rig to Characterize the Gust Response of Small Wind Turbines and Autorotating Seeds
… decreasing durations over which the simulated gusts occurred.
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Maneuver-Based Motion Control of a Miniature Helicopter
… in the presence of disturbances such as wind gusts, turbulence, sensor noise, and uncertain initial conditions. For the specific plant formulations and trajectories presented, performance is comparable for both control approaches; however, it is possible to improve controller performance by …
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Reduced-order modeling and adjoint-based optimization of flows with fluid-structure interactions
… approach was applied to both 2D and 3D strong gusts, and was highly effective in recovering the target lift, while keeping a reasonable computational cost. The adjoint-ROM approach was used for 2D weak gusts. It was able to mitigate the gust impact with relatively lower controllability and …
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