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 142 for “"power spectral density"”.
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Spectrum sensing based on capon power spectral density estimation
… we propose a spectrum sensing based on the Capon Power Spectral Density (PSD) estimation method. The proposed method estimates the received PSD, and uses it to identify free and busy channels. A cooperative spectrum sensing approach is also introduced. The goal is to solve the common hidden node …
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An investigation of the power spectral density of atmospheric turbulence
Thesis (Sc.D.) Massachusetts Institute of Technology. Dept. of Aeronautical Engineering, 1950.
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Ultrasonic acoustic health monitoring of ball bearings using neural network pattern classification of power spectral density
… with low signal-to-noise ratios. Using the UAE power spectrum signature, it is possible to pose the health monitoring problem as a multi-class classification problem, and make use of a multi-layer artificial neural network (ANN) to classify the UAE signature. One major problem limiting the …
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Modelling of Wall Pressure Fluctuations Induced by Turbulent Boundary Layer Flow
Semi-empirical models are used to predict the power spectral density of wall pressure fluctuations in the turbulent boundary layer. From the analysis of current semi-empirical models and a large survey of experimental data, it was found that the models proposed by Goody and Smol'yakov have the …
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A three-dimensional analytical study of spatial variability of seismic ground motions
… is modeled as a random process specified by a power spectral density function. To separate the path effect from the source effect, a multi-degree-of-freedom system is chosen as the ""substitute system"" which is characterized by the equivalent transmission effect to the deterministic wave …
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Haze measurements through image analysis
… were analyzed to obtain image contrast, and power spectral density functions. The power spectral density functions were characterized by maximum power, full width at half maximum, second and third moments, and exponential fit. Out of these methods, contrast and exponential fit results showed …
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Resistance fluctuation spectroscopy and other transport behavior in lanthanum barium copper oxide
… small, fluctuating domains. In most samples, the power spectral density of resistance noise increases as temperature is lowered below the charge-ordering temperatures expected for LBCO. The power spectral density of resistance fluctuations is found to scale with inverse frequency, consistent with …
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An Efficient Method to Assess Reliability under Dynamic Stochastic Loads
… there are considerable uncertainties in the power spectral density functions of the wave elevations or the wind speeds. Therefore, it is necessary to evaluate the reliability of a system for different power spectral density functions of the input loads. The reliability analysis of dynamic …
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Mathematical modeling of river water temperatures
<p>"The applicability of power spectral density techniques, Fourier series analysis, and linear regression to the mathematical modeling of river water temperature is demonstrated. Consideration is also given to the problem of estimating thermal inputs to rivers from man-made sources such as …
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Comparison of 4.5 Hz Geophones and a Broadband Seismometer in a Real Field Deployment
An analysis of waveforms, power spectral density and array responses was performed using geophones and broadband seismometers, co-deployed as part of a geologically motivated study. Broadband seismometers record excellent waveforms but, due to cost and deployment effort, wavefields are usually …
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A General Formulation of Neutron Noise for Fast Reactor Systems
… formalism is developed in order to analyze zero-power neutron noise experiments in fast reactor systems. A generalized dispersion equation is combined with theoretical expressions for the experimentally measured power spectral density and variance-to-mean ratio which makes it possible to express …
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Image Evolution Using 2D Power Spectra
… Based on existing research which uses power spectral density of spatial frequencies as an effective metric for image classification and retrieval, we believe this measure and others based on Fourier decomposition may be effective for guiding evolutionary texture synthesis. We briefly …
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New Model And Simulation Algorithm Of Nonstationary Non-gaussian Ground Motions Based On S-transform
… be represented by time-frequency (dependent) power spectral density (TFPSD) and coherence functions. The assessment of such power spectral density and coherence functions are presented by using historical records and the S-transform – a Fourier transform with time localized and …
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Models for the study of neuronal activity during cognitive tasks
… of various connectivity patterns in cortical EEG power spectral density (PSD), and investigate the possibility to derive connectivity circuits from EEG data. To this end, two different models have been built. In the first model an individual region of interest (ROI) has been built as the parallel …
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Applications of noise theory to plasma fluctuations
… these models, the correlation function and the power spectral density of random fluctuations. We also find that the fluctuation-induced transport coefficients may be estimated by the correlation length and the correlation time. The theoretical results are compared with the observed plasma …
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Computational Optical Imaging Systems for Spectroscopy and Wide Field-of-View Gigapixel Photography
… system would maximize resolution in time, spectral bandwidth, three-dimensional object space, and polarization. Practically, increasing any one parameter will correspondingly decrease the others.</p><p>Spectrometers strive to measure the power spectral density of the object scene. …
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Exploring Anisotropic Noise and Fast Gates with Superconducting Qubits
… approximately Lorentzian transition in the noise power spectral density below 1 Hz, and (2) noise suppression above 1 MHz. Our second result is the suppression of coherent qubit-control errors induced by the counter-rotating component of strong, linearly-polarized drives. We establish two …
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The effect of segment averaging on the quality of the Burg spectral estimator
The Burg spectral estimator (BSE) exhibits better peak resolution than conventional linear spectral estimators, particularly for short data records. Based on this property, the quality of the BSE is investigated with the available data record segmented and the relevant parameters or functions …
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