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 62 for “"Acoustic Noise"”.
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Aircraft interior acoustic noise control
… materials are best suited for internal aircraft noise reduction. An impedance tube with dimensions of a scaled aircraft was constructed and evaluated, and eleven materials were tested and compared based on their noise reduction properties, weight, and thickness. Polyvinylidene Fluoride was tested …
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Acoustic noise suppression for helicopter communication systems
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1993.
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Piezoceramic Actuated Transducers for Interior Acoustic Noise Control
… capacity of launch vehicles is to reduce the acoustic environment in the interior of the fairing. A major problem is that passive methods currently used for noise suppression do not exhibit significant energy dissipation at low frequencies. This motivates the use of active noise control. Using …
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The analysis of acoustic noise in a submerged arc furnace
This project deals with Acoustic Noise Analysis in a submerged Arc Furnace. Operators and Metallurgists believe that the acoustic noise coming from the furnace conveys information as to the operating conditions of the furnace. This submerged arc furnace reduces ferrochrome ore to the metal. A …
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Origin and reduction of acoustic noise in variable-reluctance motors
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1990.
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The reduction of acoustic noise emissions from a hard disk drive
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1994.
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Very low frequency seismo-acoustic noise below the sea floor (0.2-10 Hz)
Ambient noise in the sea has been observed for over 100 years. Previous studies conclude that the primary source of microseisms is nonlinear interaction of surface gravity waves at the sea surface. Though this source relationship is generally accepted, the actual processes by which the wave …
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Very low frequency seismo-acoustic noise below the sea floor (0.2-10 Hz)
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, and the Woods Hole Oceanographic Institution, 1994.
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Linear iron-core permanent magnet motor with high force and low acoustic noise
Acoustic noise and associated vibration are potentially troubling characteristics of electric machines including variable-reluctance motors, induction machines, and permanent magnet synchronous motors. The severity of this problem depends on the types of motors and their applications. One exemplary …
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Measurements of the horizontal directionality of the ambient acoustic noise in Monterey Bay, California
… of some of the horizontal characteristics of acoustic ambient noise were carried out in the south-eastern parts of Monterey Bay, California, at a limited number of stations and for a limited number of ambient conditions. Directional hydrophones on buoys located at ranges of two to four miles …
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Modeling and analysis of source-commutated five-phase diode rectifier systems
… the source (and subsequently mitigate) the acoustic noise produced by an automotive alternator. Based upon the finding that torque ripple is a dominant noise source, effort has been focused upon creating a machine-rectifier system that has maximum output power and minimal acoustic …
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Acoustically optimized propulsion systems using a Cause-Effect Controller
The proposed Acoustic Response Control Process (ARCP) allows for a "Cause- Effect" Controller (CEC) to provide a method to optimize the trade-off between a marine vessel's ability to maneuver and the radiated acoustic noise (or internal vibrations). Through the discretization of both a marine …
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Bearing Estimation for Underwater Acoustic Source Using Autonomous Underwater Vehicle
… the challenges 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 …
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Noise reduction during diffusion tensor imaging of infants
Acoustic noise produced during echo planar imaging (EPI) has been known to reach excessive levels. In addition to causing general patient discomfort and anxiety, this level of noise makes the scanning of young children and infants particularly difficult. Infants are typically scanned while sleeping …
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Pitch determination of speech signals in the presence of noise
… of the algorithms under different conditions of acoustic noise, and the real-time implementation of one of the algorithms using a high speed single-chip digital signal processor. The thesis presents a discussion on the applications of pitch determination algorithms for speech, followed by a …
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Modeling and Analysis Methods for ESD and EMI Problems
… methodology is presented to analyze the acoustic noise created by MLCCs on a PCB. A simulation model for the PCB vibration modal response is built to analyze the harmonic response of the PCB excited by the capacitor. Total response is obtained by multiplying the measured power noise …
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Methods for functional brain imaging
… discriminate against detrimental physiological noise. To accomplish this it exploits highly accelerated parallel imaging techniques and MRI signal detection with a large number of coil elements. We then address a major problem in the application of fMVIRI to auditory studies. In standard fMRI, …
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Adding DSP enhancement to the Bose® Noise Cancelling Headphones
… use on the audio path in the Bose QuietComfort® Acoustic Noise Cancelling® [5] Headphones was designed and implemented. The purpose was to demonstrate that digital processing was feasible for this type of portable consumer product, and to design and add new equalization and adaptive abilities not …
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Geometry optimization of dry ice blasting nozzle for the noise reduction using experimental validation
… of dry ice blasting (DIB), it produces a high noise exposure. The noise exposure during a high blasting pressure may reach up to 130 dB which is considered a harmful noise level (standard 90 dB for eight working hours per day). At present, safety measures are taken according to administrative …
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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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