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.
Results
Showing 1 to 19 of 19 for “"self-noise"”.
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Airfoil Self-Noise Prediction Using Neural Networks for Wind Turbines
… prediction method has been developed to compute self-noise of airfoils typically used in wind turbines. The neural networks were trained using experimental data corresponding to tests of several different airfoils over a range of flow conditions. The experimental data corresponds to the NACA …
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Bearing Estimation for Underwater Acoustic Source Using Autonomous Underwater Vehicle
… involved in detecting sources of acoustic noise using an autonomous underwater vehicle (AUV) in real world environments. The initial part of this thesis describes the developments made for redesigning an acoustic sensing system that can be used to estimate the relative bearing between a …
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Aeroacoustic control of landing gear noise using perforated fairings
… of perforated fairings for landing gear noise control. The sparse knowledge about this new subject has necessitated a more fundamental study involving a basic fairing-strut configuration, followed by wind tunnel tests on a simplified landing gear configuration incorporating perforated …
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Geração de ruído por jatos turbulentos
… that, to obbey energy conservation, the shear noise/self noise model requires interference between the two types of terms to occur. The importance of source coherence in the sound field is discussed, and some evidences against this hypothesis are raised. Far field sound pressure correlations …
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Noise analysis of switched capacitor filters
The self noise output of switched-capacitor (SC) filters was examined. The two main noise sources in SC filters are switch transistors and the operational amplifiers. These noise sources were modeled as switch thermal white noise and op-amp input white noise. The existence of direct and …
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Non-data aided digital feedforward timing estimators for linear and nonlinear modulations
… at this rate when the operating signal-to-noise ratio (SNR) and the excess bandwidth are low. We propose another alternative estimator for operating at the Nyquist rate that has reduced self-noise at high SNR for large rolloff factors. This can be viewed as an extension of the timing …
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Evaluation by simulation of an acoustic array composed of multiple autonomous vehicles
… driven by the need for high sensitivity, low self-noise, and response across a wide range of frequencies. Robotic autonomy, as applied to acoustic sensors, is currently operationally limited to deployment of traditional arrays from semi-submersible tow vehicles. while such a configuration …
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Aerodynamic and Aeroacoustic Analysis of Low Reynolds Number Propellers Using Higher-Order RANS Transition Turbulence Modeling
… its aerodynamic performance as well as the noise generated. Capturing these effects in our computational models is necessary to further our understanding of rotor aerodynamics and acoustics. The current study has introduced a novel RANS transition turbulence model, SSG/LRR-$\omega$-$\gamma$, …
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An Exploration of the Acoustic Detection and Localization of Small Uncrewed Aerial Systems
… of filtering techniques to try to filter sUAS self-noise is compared to alternative methods such as a ballistic sampling period where the motors of the sUAS are momentarily turned off to reduce noise. A final recommendation of a multi-sensor suite of microphones, cameras, along with other …
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Analysis, Design and Implementation of Multichannel Audio Systems
… framework requirements. Their robustness to<br/>self-noise is assessed and measurements of a third-order prototype are<br/>presented. Finally, a scalable and interactive room acoustic simulator<br/>is proposed to enable virtual recordings in simulated sound elds.
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Perceptual and acoustic impacts of aberrant properties of electrolaryngeal speech
… would produce the most benefit. Removing the EL self-noise and correcting for a lack of low frequency energy would also improve EL speech, but to a lesser extent. However,
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Design and Development of a Hydrophone Array for an Autonomous Underwater Vehicle Capable of Real-Time Detection and Tracking of Surface Vessels
… the frequency range of broadband surface vessel noise, review of literature, financial as well as structural constraints of the AUV. The post-processing algorithm, developed using a phased array principle called acoustic beamforming, outputs real-time heading angles of the target surface vessels. …
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Comparison of 4.5 Hz Geophones and a Broadband Seismometer in a Real Field Deployment
… down to 0.02 Hz (50 s). For quiet ambient noise, the waveforms strongly correlate down to <0.25 Hz (4 s) and the power spectral density match to the low-frequency side of the microseismic peak at ~0.15 Hz (~7 s). By deploying a much larger number of geophones, waveforms can be stacked to …
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Numerical studies of the flow around an airfoil at low Reynolds number
… With no forcing the turbulence is observed to 'self-sustain', with increased turbulence intensity in the reattachment region. A comparison of the forced and unforced cases shows that the forcing improves the aerodynamic performance whilst requiring little energy input. Linear stability analysis …
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Hybrid wing-body aircraft noise and performance assessment
Hybrid wing-body aircraft noise generation and boundary layer ingestion (BLI) performance trends with increased fan face Mach number inlet designs are investigated. The presented topics are in support of the NASA subsonic fixed wing project, which seeks to lower noise and increase performance by …
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Bio-Inspired Axial Fan Design, 3D Printing Fabrication and Characterization for Noise and Flow Performance Optimization
Noise pollution from mechanical ventilation systems is an increasingly critical issue in the context of global energy transition, post-pandemic air quality requirements, and stringent environmental acoustic regulations. In this context, axial-flow fans represent a key technological component, …
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Towards a silent fan: an investigation of low-speed fan aeroacoustics
The noise (unwanted sound) from fans of all sizes, operating in close proximity to people, can be a design constraint due to annoyance or, in the worse cases, health damage. Of the total noise, aeroacoustic noise – produced by unsteadiness in the air – often represents a significant source and is …
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Measurement and Prediction of Rotor Noise Sources for sUAS in Outdoor and Laboratory Environments
… comparison of aerodynamic performance and noise of eVTOL rotors operating in multiple facilities, and analysis of the noise associated with an outrunner brushless DC motor. Empirical and low-order models are used to predict aerodynamic performance, tonal noise, and broadband noise for …
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Development of techniques for earthquake microzonation studies in different urban environment
… are estimated by means of single-station noise measurements. The microzonation is performed in terms of problem-dependent quantities, by considering a proxy suitable to link information from the first layer to the second one. In order to define the microzonation approach proposed in this …