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 50 for “"Active Noise Control"”.
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Multiple Reference Active Noise Control
The major application of active noise control (ANC) has been focused on using a single reference signal; the work on multiple reference ANC is very scarce. Here, the behavior of multiple reference ANC is analyzed in both the frequency and time domain, and the coherence functions are provided to …
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Active noise control in a luxury vehicle
Structure-borne road noise is a critical sound attribute for the overall Noise Vibration& Harshness (NVH) performance of modern luxury vehicles. Currentpassive NVH solutions require structural design modifications, in order to controllow frequency sources that cause structure-borne noise. Active …
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Active noise control using glow discharge plasma panels
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2001.
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Theory and Design of Spatial Active Noise Control Systems
The concept of spatial active noise control is to use a number of loudspeakers to generate anti-noise sound waves, which would cancel the undesired acoustic noise over a spatial region. The acoustic noise hazards that exist in a variety of situations provide many potential applications for spatial …
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Theory and Design of Spatial Active Noise Control Systems
The concept of spatial active noise control is to use a number of loudspeakers to generate anti-noise sound waves, which would cancel the undesired acoustic noise over a spatial region. The acoustic noise hazards that exist in a variety of situations provide many potential applications for spatial …
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Laser Doppler Vibrometry Based Remote Sensing for Active Noise Control
Demands for active noise control/cancellation (ANC) to provide a quiet environment have grown significantly over the past few decades. Notably, many ANC headphones and earphones have emerged and gained much success in the market due to their excellent performance and robustness. There are also …
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Optimization of Active Noise Control for Small Axial Cooling Fans
Previous work has shown that active noise control is a feasible solution to attenuate tonal noise radiated by small axial cooling fans, such as those found in desktop computers. One such control system reduced noise levels of a baffled 80-mm fan in the free field with four small loudspeakers …
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Active noise control of supersonic impinging jet using pulsed microjets
This thesis concerns an active noise control of supersonic impinging jet flow using unsteady microjet injection. Supersonic impinging jet involves several problems such as lift loss, ground erosion, significant noise pollution, and sonic fatigue, all of which are dominated by impinging tones mainly …
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Feedback Applications in Active Noise Control for Small Axial Cooling Fans
Feedback active noise control (ANC) has been applied as a means of attenuating broadband noise from a small axial cooling fan. Such fans are used to maintain thermal stability inside of computers, projectors, and other office equipment and home appliances. The type of low-level noise radiated from …
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Performance Limits of Active Noise Control for Nonlinear Systems: A Machine Learning Perspective
Active noise control (ANC) uses microphones and actuators to minimise unwanted noise and improve sound quality and comfort. This thesis investigates the performance limits of ANC systems in nonlinear dynamical systems, with a particular emphasis on automotive and headphone applications. Both …
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On Implemintation of Loudspeakers for Feedback Control, Open-Air, Active Noise Control Headsets
The loudspeakers used in active noise reduction (ANR) headsets are generally identical to loudspeakers used in commercial headphones. Unfortunately, the frequency response characteristics of these loudspeakers are not particularly well suited for open-air active noise control (ANC). Open-air …
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Prediction of low-frequency sound-pressure fields in fitted rooms for active noise control
Low-frequency noise is a health concern for workers in industrial workshops; rooms of highly varying size and dimensions, usually containing obstacles (the ‘fittings’). Low-frequency noise can be generated from sources such as reciprocating or rotating machinery, or ventilation systems. As the …
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Optimization of Control Source and Error Sensor Locations in Free Field Active Noise Control
<p>Previous work has shown that active noise control (ANC) can be applied to axial cooling fans. Optimization of the control source and error sensor placement is desired to maximize the attenuation using ANC. A genetic algorithm was developed to find the optimal placement of control sources for a …
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Application of Active Noise Control to Reduce Cabin Noise in Single Engine General Aviation Aircraft
<p>The application of active noise control to reduce cabin noise in single engine, general aviation aircraft is investigated through the use of the 'filtered x' least mean square algorithm and a simple acoustic feedforward method to generate a reference signal is tested. The system is designed to …
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Error Sensor Strategies for Active Noise Control and Active Acoustic Equalization in a Free Field
… error signals to determine how to appropriately control a sound field. These include pressure, particle velocity, energy density and intensity. In this thesis, numerical models are used to show which signals perform best in is free-field active noise control (ANC) using error sensors located in …
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Active noise control in supersonic impinging jets using pulsed microjets : actuator design, reduced-order modeling
… reduces the adverse effects. The amount of noise reduced by microjet actuation is known to be dependent on nozzle operating conditions. In this paper, two active control strategies using microjets are suggested to maintain a uniform, reliable, and optimal reduction of these tones over the …
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A regression-based approach for simulating feedfoward active noise control, with application to fluid-structure interaction problems
… numerical tools for simulating feedforward active noise control in the frequency domain. Feedforward control is numerically similar to linear least squares regression, and can take advantage of various numerical techniques developed in the statistics literature for use with regression. …
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Numerical Study of Synthetic-Jet Actuation Effect on Airfoil Trailing Edge Noise
… of employing Synthetic Jet Actuators (SJAs) as active noise control devices for reduction of airfoil acoustic radiation. High-accuracy numerical efforts employ a sixth-order accurate Navier-Strokes solver implementing a low-pass filtering of poorly resolved high-frequency solution content to …
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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 …
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The active minimisation of harmonic enclosed sound fields, with particular application to propeller induced cabin noise
… secondary acoustic sources for the reduction of noise levels in harmonically excited enclosed sound fields. This possibility is studied initially through the use of an analytical model of a single frequency 'two-dimensional' rectangular, enclosed sound field of low modal density. Quadratic …
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