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 10 of 10 for “"Cross Spectrum"”.
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Reconstruction of stellar images from correlations
… of the unknown object using the "self cross correlation” is proposed and implemented. This self cross correlation is defined as the cross correlation between an image observation and a truncated part of it. The relation amongst the phase of the cross spectrum, the phase of the object …
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Tools, techniques, and early results in studies of 21 cm, Lyman-alpha, and H-alpha emission from the cosmic dawn
… & Tegmark. We assess the real world prospects of cross-correlation measurements between 21 cm, Lyman-a, and H-a emission from the EOR. We show that geometric effects produce percent-level correlations between low frequency radio fluxes and nearinfrared fluxes, and we set the first limit on the …
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An Inverse Theory Approach to Incoherent Scatter Drift and Temperature Estimation at the Jicamarca Radio Observatory
… to the magnetic field. Using Doppler spectrum estimation techniques we are able to measure line-of-sight drifts with uncertainties as low as ∼0.5 m/s at signal to noise ratios as low as ∼0.1. In applying this technique to data obtained at the Jicamarca Radio Observatory we have …
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Reconstructing the Sky with CMB Lensing methods
… and future high significance CMB lensing-galaxy cross-correlations will soon precisely probe the growth of structure and provide powerful tests for parameter tensions, non-Gaussianity, neutrino mass, and modifications to Λ−CDM and gravity. However, such cross-correlations are sensitive to CMB …
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Monitoring and Imaging Seismic Velocity Changes Across Temporal and Spatial Scales
… seismic travel-time shifts based on wavelet cross-spectrum analysis. This new method provides stable time-shift measurements with optimal time-frequency joint resolution that can enhance the high-resolution spatial imaging of dv/v. This dissertation advances the techniques and applications of …
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An earth image simulation and tracking system for the Mars Laser Communication Demonstration
… systems will cover the rest of the frequency spectrum. Before testing candidate Earth-tracking algorithms, simulated Earth image sequences were created to provide test; data sets. While a plain centroiding algorithm, thresholded-centroiding algorithm, cross-spectrum phase correlation method, …
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Interference of Intensity Noise in a Multimode Nd:YAG Laser
… of the excitation is unknown, we develop the cross spectral technique to measure the antiphase dynamics directly and form a picture of the intensity noise interference for two to five mode operation. For three mode operation, we measure the contributions of the longitudinal modes to the …
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Turbulent Boundary Layer Superstructures Near the Wall and Their Relationship to Wall-Pressure Fluctuations
… in the relationship. A wavenumber-frequency cross-spectrum of the pressure and streamwise velocity reveals the convective ridge dominating the flow. However, significant spectral levels in the sub-convective region, roughly 20 dB below the convective ridge are shown at low frequencies, …
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Prediction of Trailing Edge Noise from Two-Point Velocity Correlations
… a surface can be computed by the integral of the cross product between the velocity and vorticity fields, of the boundary layer and shed vorticity (Howe (1978)). To extract the source terms, proper orthogonal decomposition is applied to the velocity cross spectrum to extract modes of the unsteady …
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Heart Rate Variability analysis in patients undergoing local anesthesia
… signal and the respiration signal and uses the cross-spectrum between these two signals to obtain the boundaries related to the HF band of the signal. The boundaries related to the LF band were defined using the HRV signal spectrum alone. The boundary estimation technique was applicable in all …