Global ETD Search
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Showing 1 to 8 of 8 for “"active/passive control"”.
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Acoustic Devices for the Active & Passive Control of Sound in a Payload Compartment
… resonators and loudspeakers used for noise control in rocket payload compartments are developed. Second, active control using a hybrid control system (with structural and acoustic actuators) was tested experimentally. Due to the weight limitations for this application, Helmholtz resonators …
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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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Active/Passive control of fluid-borne and structure-borne disturbances in fluid-filled piping systems
… fluid and shell walls. It is necessary to devise control approaches that tackle both components of the excitation simultaneously. This study will demonstrate new approaches in active and passive control techniques and show their advantages over classical control approaches. It is necessary to …
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Active, Passive and Active/Passive Control Techniques For Reduction of Vibrational Power Flow in Fluid Filled Pipes
… flow in fluid filled piping systems makes its control and subsequent reduction a difficult problem. This work experimentally explores the potential of different active, passive and active/passive control methodologies for control of vibrational power flow in fluid filled pipes. Circumferential …
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A dual reaction-mass dynamic vibration absorber for active vibration control
… be increased by the addition of an externally controlled force, generally applied between the reaction-mass and the primary structure. Such devices are known as hybrid DVAs. This thesis presents a new hybrid DVA configuration which utilizes two reaction-masses in parallel. On this proposed …
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A Study of Smart Foam for Noise Control Applications
Smart foam is a composite noise control treatment that consists of a distributed piezoelectric actuator, known as polyvinylidene fluoride (PVDF), embedded within a layer of partially-reticulated polyurethane foam. The principal function of smart foam is to yield broadband sound attenuation. Passive …
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Compact Integrated Active-Passive Approach for Axial Fan Noise Control
A new active-passive approach for the control of noise radiated from a small axial fan was investigated. The approach involved the installation of an axial fan into a short duct with both passive and active noise control functions. First, a systematic methodology for the analytical modeling of …
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Advanced modeling of active control of fan noise for ultra high bypass turbofan engines
An advanced model of active control of fan noise for ultra high bypass turbofan engines has been developed. This model is based on a boundary integral equation method and simulates the propagation, radiation and control of the noise generated by an engine fan surrounded by a duct of finite length …