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 28 for “"structural vibrations"”.
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Structural vibrations in acoustic fields
… function is required for the calculation of structural response to jet noise. An approximate form of this function is utilised in a calculation of the response of a flat panel close to an air jet.<br/><br/>Space correlation measureinents in the region within five jet diameters of the orifice …
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Techniques for Controlling Structural Vibrations
… tackle the problem of suppressing high-amplitude vibrations of cantilever beams when subjected to either primary external or principal parametric resonances. Guided by results of previous investigations into the nonlinear dynamics of single- and multi-degree-of-freedom structures, we design …
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Fiber optic modal domain sensing of structural vibrations
… fiber optic sensors to the detection of structural vibration. Several laboratory vibration systems which demonstrate a range of component frequencies and dynamic range are analyzed in an effort to characterize the sensor's behavior. We compare frequency spectra of the sensor output with …
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Experimental-theoretical study of velocity feedback damping of structural vibrations
This study concerns the active damping of structural vibrations through the application of various forms of velocity feedback control. Active damping will be required for large space structures which are performance-sensitive to motion or inaccurate pointing. Several control forms, including …
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Development of Novel Eddy Current Dampers for the Suppression of Structural Vibrations
… structure is deployed in space, it is subject to vibrations induced mechanically by guidance systems and space debris as well as thermally induced vibrations from variable amounts of direct sunlight. For the optimal performance of the satellite, it is crucial that the vibration of the membrane be …
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Using Magneto-Rheological Dampers in Semiactive Tuned Vibration Absorbers to Control Structural Vibrations
… (TVAs) have shown to be effective in suppressing vibrations of machines and structures. A vibration absorber is a vibratory subsystem attached to a primary system. It normally consists of a mass, a spring, and a damper. Mounted to the primary system, a TVA counteracts the motions of the primary …
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Electromechanical Coupling of Distributed Piezoelectric Transducers for Passive Damping of Structural Vibrations: Comparison of Network Configurations
… devices for the suppression of mechanical vibrations is investigated by a wave approach, considering both the extensional and flexural oscillations. The optimal values of the electric parameters for a fixed network topology are derived analytically by a pole placement technique. Their …
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Effect of air on vibration of structures
… may help in determining the characteristics of structural vibrations — from acoustic behavior to earthquake response - in practical buildings. The work consists of several primary components: derivation of theories that predict the effect of air on structural vibrations and vice-versa, design of …
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Robust analysis and control of smart structural systems
"For successful development of smart structural systems to control structural vibrations, the actuator/sensors should be configured at locations giving maximum control effectiveness, and the systhesized controller has to be robust for uncertainties such as uncertain parameters and saturating …
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Computational Modal Analysis Of A Half-Scale Business Jet Fuselage Tail Section
In aircraft, acoustic noise and structural vibrations are critical aspects of what determines the comfort of passengers throughout the duration of their trip. As such, there is great value in being able to reduce noise and the structural vibrations that cause noise to improve the quality of the …
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Simultaneous active passive/control of extensional and flexural power flows in infinite thin beams
Passive control techniques to minimize structural vibrations are limited with respect to the amount of attenuation obtained especially in the low-frequency region but do not require adding any power. Active control methods are effective for reducing structural vibrations, especially at low …
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A model for Hybrid Dynamic Beam Movement with Specific Application to Wind Energy Units
The aim of this thesis is to present a structural model for a wind turbine and its supporting pylon, to analyze and simulate attendant vibration phenomena and to suggest and simulate an appropriate control procedure. A wind turbine can be described as an elastic system consisting of distributed …
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The study and development of distributed devices for concurrent vibration attenuation and energy harvesting
This work focuses on the broadband attenuation of structural vibration and, in the process, employs a new perspective of vibrational energy harvesting devices. The first part of the research studies and develops a continuously distributed vibration control device which combines the benefits of …
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Adaptive Control using IIR Lattice Filters
… implement an adaptive controller that damps the structural vibrations induced in a multi-modal structure. The adaptive controller utilizes an adaptive infinite impulse response lattice filter for improved damping over the fixed feedback controller alone. An adaptive finite impulse response LMS …
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A Distributed Active Vibration Absorber (DAVA) for Active-Passive Vibration and Sound Radiation Control
… new active-passive treatment developed to reduce structural vibrations and their associated radiated sound. It is a contribution to the research of efficient and low cost devices that implement the advantages of active and passive noise control techniques. A theoretical model has been developed to …
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Improving the Structural Dynamics of Slender Beam-like Structures
… a new method is developed based on minor structural modifications. Three applications are chosen to demonstrate the new method. The first is the sensing wire oscillations of a hot-wire probe. The second application is the problem of tool chatter due to milling tool vibration, while the …
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Closed-loop control of vortex shedding by means of Lorentz force
… force on the cylinder leading to cross-stream structural vibrations. Flow control to either delay the appearance of vortex shedding or fully suppress it has attracted much attention during the last decade. The focus of this dissertation is to control vortex shedding from a circular cylinder by …
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Reduced Order Modeling of a Rocket Engine Turbopump Inducer for Assessment of Pogo Instability
… arises from the interaction of vehicle structural dynamics with thrust oscillations of a liquid fueled propulsion system. These thrust oscillations are a result of the pressure fluctuations that originate in the piping system, the injector, the combustion chamber, and/or the turbopump …
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Uncertainty quantification of engineering systems using the multilevel Monte Carlo method
… are compared for two prototypical examples: structural vibrations and buoyancy driven flows through porous media. In the first example, the impact of random mass density is quantified for structural vibration problems in several dimensions using the multilevel Monte Carlo method. Comparable …
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A Multi-Sensor Passive Occupant Localization
… determines occupant positions by analyzing floor vibrations caused by footfall patterns. Unlike traditional localization techniques that rely on visual or radio-based sensing, vibro-localization leverages accelerometers fixed to the floor to capture vibro-measurements, offering a cost-effective …
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