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 “"Passive Damping"”.
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Passive damping of a LIGO mirror
… In this thesis I test a method to passively damp the acoustic modes of the mirror, using a mass-spring damper. The damper can be modeled as a piezoelectric "spring" (PZT) connected to a seismic mass. The damper can lose energy from both mechanical motion, and motion of charge …
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Passive Damping in Stiffened Structures Using Viscoelastic Polymers
… these unwanted vibrations from a system is passive damping, by using a viscoelastic material. This dissertation will primarily focus on constrained layer passive damping treatments in structures and the investigation of associated complex modes. The key idea behind constrained damping …
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The virtues of passive damping for feedback controlled flexible structures
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1991.
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Passive damping mechanism of Herschel-Quincke tubes for pressure pulsations in piping systems
… a phenomenon known as acoustic resonance. Passive damping devices such as the Herschel-Quincke (HQ) Tube can be implemented into a resonant system to mitigate the pressure pulsations. Some practical considerations have been clarified in the current work which include the normalization of …
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Electromechanical Coupling of Distributed Piezoelectric Transducers for Passive Damping of Structural Vibrations: Comparison of Network Configurations
In this work passive piezoelectric devices for vibration damping are studied. It is developed the basic idea of synthesizing electrical wave guides to obtain an optimal electro-mechanical energy exchange and therefore to dissipate the mechanical vibrational energy in the electric form. Modular …
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Polysiloxane-polyarylester block copolymers: synthesis and characterization
Passive damping has been defined as a key element in vibration control. It is believed that the approach to passive damping could be addressed through the use of carefully designed viscoelastic polymeric materials. This dissertation describes the synthesis and characterization of multiphase, …
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Effect of Control Techniques on the Performance of Semiactive Dampers
… using the more conventional control methods of passive damping, Skyhook control, and Hybrid control. The conventional control methods results confirm that the semiactive damper possesses a number of benefits when compared to passive damping. In addition, the alternative control methods, which …
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Dynamic Analysis of Semi-Active Control Techniques for Vehicle Applications
… was compared to the performance of conventional passive damping. Each control policy is evaluated for its control performance under three different base excitations: chirp, step, and pure tone. Corresponding to the chirp input, transmissibilities and auto spectrums are considered for each control …
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An Experimental Evaluation of the Application of Smart Damping Materials for Reducing Structural Noise and Vibrations
This study evaluates the application of smart damping materials for reducing structural noise and vibrations. The primary purposes of this study are to: 1. Explore the feasibility of smart damping materials, such as piezoelectric materials, for augmenting and improving the noise and vibration …
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Granular sloshing absorbers for vibration control
… subjected to wind, earthquakes or other shocks. Passive and active absorbers are employed, often at great expense, to stabilise the structures for the safety and comfort of the occupants. Current passive damper technologies include Tuned Mass Dampers and Tuned Liquid Dampers. These devices …
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Hybrid damping system for high-rise building outriggers
… system and an ideal location for building damping systems. However, current damping for outriggers are limited to passive dampers. Although they can mitigate the fundamental vibration mode effectively, their non-adjustable property limits their efficiency. The objective of this thesis is to …
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Dynamic range implications for the effectiveness of semi-active tuned mass dampers
… of a tuned mass damper (TMD), which acts as a passive damping device in the region of the tuned frequency. However, TMDs exhibit a limited bandwidth and often require a significant mass. Active systems, such as the active mass driver, have been utilized to improve the effectiveness of the TMD …
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Numerical analysis of a tape spring hinge folded about two axes
… which allows the designer to determine adequate passive damping to obtain necessary post-deployment stability and pointing accuracy.'
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Element and system design for active and passive vibration isolation
… strains on the order of 10-²¹. We develop novel passive elements and control strategies as well as a framework for concurrent design of the passive and active elements of single-stage and multi-stage isolation systems. In many applications, it is difficult to construct passive isolation systems …
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Experimental Evaluation of Semiactive Magneto-Rheological Suspensions for Passenger Vehicles
… response of the quarter-car system with only a passive damper. Next, the passive damper was replaced with a controllable MR damper. The control schemes of skyhook, groundhook, and hybrid semiactive control were applied to the MR damper. The physical response of the quarter-car with the different …
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Reinforcement learning based control for arrays of point absorber wave energy converters
… a control system to select different values of damping acting on the point absorber through the PTO. The selection of values can be achieved using reinforcement learning algorithms, such as Q-learning. Performance of the control system was evaluated through simulation of the point absorber. For …
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Experimental Investigation and CFD Simulation of Active Damping Mechanism for Propellant Slosh in Spacecraft Launch Systems
… of such slosh events is not trivial. Several passive mechanisms with limited operating range are currently used to mitigate the effects of slosh. An active damping mechanism concept developed here can operate over a large range of slosh frequencies and is much more effective than passive …
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Integrated modeling and dynamics simulation for the next generation space telescope
… which leads to high modal density and light damping of the structural plant. An integrated model comprising multiple disturbance sources, structures, optics and control systems was developed in order to predict the expected dynamic performance of the observatory in terms of wavefront error …
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Estimation of Elastic and Damping Characteristics of Viscoelastically Constrained Carbon Strands
… have low package volume and possess excellent damping characteristics. Substantial damping is required in space since there is no surrounding medium to provide damping. Such a construction uses composites in a fabric form that displays viscoelastic behavior. The viscoelastic behavior is …
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Dynamics and Control for Vibration Isolation Design
… transmissibility increases when the isolator has passive damping although this does not occur for an isolator implementing active damping. A severe limitation of this system is that it cannot be used when the base and/or equipment are flexible. System flexibility has been considered in previous …
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