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 10 of 10 for “"delay and sum"”.
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3D echo cancellation in a home environment
… describes the work done to research, implement, and compare various algorithms for the cancellation of echoes in a home environment, where the room impulse response is unknown and variable. The general problem, where the speaker's movements are completely unrestricted, is a very hard one, and …
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Multiplexer Design for a Multi-Array Ultrasonic Imaging System
… platforms have a limited number of I/O channels, and thus cannot be directly interfaced with multiple ultrasound transducer arrays. A high-voltage multiplexer is designed to allow a 128-signal DAQ to interface with up to eighteen 128-signal arrays in a time-multiplexed manner. The multiplexer is …
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Cough sound discrimination in noisy and reverberant environments using microphone arrays
… are capable of distinguishing between dry and wet cough types. The performance of such algorithms, however, is affected by noise and reverberation which might exist in patients' environments. In this thesis, the performance of the previously developed cough sound discriminator in a noisy …
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Phased Array Beamsteering in Composite Laminates for Guided Wave Structural Health Monitoring
… algorithms derived for isotropic materials assume omnidirectional wave propagation. Due to inherent anisotropy in composites, guided wave propagation varies with direction and wavefronts no longer have perfect circular shapes.</p> <p>By examining slowness, velocity and wave curves, as well as …
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A Turbo Approach to Distributed Acoustic Detection and Estimation
… a platform for accurately comparing current and future data fusion theories. This thesis proposes a simulator model for testing fusion theories for these acoustic multi-sensor networks. An iterative, lossless data fusion algorithm was presented as the model for simulation development. The …
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Development Towards the use of Beamforming and Adaptive Line Enhancers for Audio Detection of Quadcopters
… Aerial Systems (UASs), such as quadcopters and hexacopters, has steadily increased over the past few years in both recreational and commercial use. This increased availability to purchase such systems has also given rise to many safety and security concerns. A common concern is that the …
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Null subtraction imaging technique for biomedical ultrasound imaging
… in an improved image with less distortion and fewer artifacts. In general, apodization is used to lower sidelobes in exchange for increasing the width of the mainlobe and thus decreasing lateral resolution. Null subtraction imaging (NSI) is a nonlinear image processing technique that uses …
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Sound from Rough Wall Boundary Layers
… at a lower level than the noise created by edges and bluff body flows, but for applications with large surface area to perimeter ratios at low Mach number, this noise source can have considerable levels. In the first part of this dissertation, a detailed study is made of the ability of the Glegg & …
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Virtual source aperture ultrasonic imaging for non destructive testing
… the integrity of a huge variety of structures and components. Virtual Source Aperture (VSA) is an new advanced method of testing and is considered to be a hybrid between traditional phased array (PA) techniques and full matrix capture (FMC). VSA overcomes the shortcoming of PA by using the …
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Backscatter Spatial Coherence for Ultrasonic Image Quality Characterization: Theory and Applications
… ultrasound systems, designed to automatically and dynamically tune imaging parameters based on image quality feedback, represent a promising solution for reducing the user-dependence of ultrasound. The efficacy of such systems, however, depends on the ability to accurately and reliably measure …