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 213 for “"Spectral density"”.
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Spectrum sensing based on capon power spectral density estimation
… 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 problem …
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Tail estimation of the spectral density under fixed-domain asymptotics
… Gaussian random field on $mathbb{R}^d$ with the spectral density $f(ulambda)$ that satisfies $f(ulambda) ~sim~ c, |ulambda|^{-theta} $ as $|ulambda| ~rightarrow~ infty$, the parameters $c$ and $theta$ control the tail behavior of the spectral density where $theta$ is related to the smoothness of …
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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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The best truncation point for the estimated spectral density function of a stationary time series
… series analysis, the scientist estimates the spectral density function of the process. One type of spectral density estimator is obtained by using the periodogram representation of the spectral density function. However, if the estimator is to be consistent, a weight function which satisfies …
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Ultrasonic acoustic health monitoring of ball bearings using neural network pattern classification of power spectral density
This thesis presents a generic passive non-contact based acoustic health monitoring approach using ultrasonic acoustic emissions (UAE) to facilitate classification of bearing health via neural networks. This generic approach is applied to classifying the operating condition of conventional ball …
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Three-Point Correlator and Pion Form Factor in Quantum Chromodynamics: Methods of Calculation for Two-Loop Spectral Density
… methods are developed of two-loop calculation of spectral density for the 3-point correlation function of an electromagnetic current and two axial currents which are the basis of the pion form factor analysis within the framework of QCD sum rules and local quark-hadron duality approach. The nature …
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Modelling of Wall Pressure Fluctuations Induced by Turbulent Boundary Layer Flow
… 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 lowest …
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Spectral densities of discrete and continuous-indexed random fields
… conditions uniformly, each will have a spectral density function (not necessarily continuous) that is bounded between two positive constants. These spectral density functions will converge in a weak sense to another function (not necessarily continuous) that is also bounded between two …
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The response of box-type structures to vibration.
… depends on the prediction of the response spectral density. To determine the response spectral density of any point on a structure a knowledge of its natural frequencies and mode shapes and modal damping factors is required. In this work the finite-element method of analysis is used to …
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A three-dimensional analytical study of spatial variability of seismic ground motions
… 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 propagation …
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AN FFT SPECTRAL ANALYSIS FOR SYSTEM IDENTIFICATION
… by the use of the information contained in the spectral density functions of a test signal applied to the system. This thesis reviews the basic relationships between a system transfer function am the spectral density functions of the system input signal am output signal. The method of obtaining …
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Haze measurements through image analysis
… 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 trend …
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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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The high energy asymptotic distribution of the eigenvalues of the scattering matrix
We determine the high energy asymptotic density of the eigenvalues of the scat- tering matrix associated with the operators H0 = −∆ and H = (i∇ + A)2 + V (x), where V : Rd → R is a smooth short-range real-valued electric potential and<br/>A = (A1, . . . , Ad) : Rd → Rd is a smooth short-range …
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Resistance fluctuation spectroscopy and other transport behavior in lanthanum barium copper oxide
… 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 the …
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An Efficient Method to Assess Reliability under Dynamic Stochastic Loads
… 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 systems …
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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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Empirical Bayes procedures in time series analysis
… model with auto-correlated errors and the spectral density function. In each case, empirical Bayes estimators are obtained using asymptotic or approximate distributions of the usual estimators. The Parzen, Tukey and Bartlett smoothing coefficients are all used in the estimation of the …
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