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 47 for “"Fourier transformation"”.
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Developing a disturbance source characterization technique for small satellite applications
… performance, is shown to be a function of the Fourier transformation type used; and we conclude which considered Fourier transformation results in the lowest prediction errors. Furthermore, we analyze how different dataset sizes and sensor-actuator pairings affect the frequency predictions.
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Lithium niobate thin films on diamond substrates for SAW devices
… response in the time domain are obtained by fast Fourier transformation. SAW activities for LiNbO3/diamond/silicon structure are observed. Discussions about the results and further improvements are presented.
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Numerical modeling and ray tracing of SPatIal Frequency modulation for Imaging
… a unique spatial frequency. By taking the Fourier transformation of the voltage verses time readout of a single element detector position data can be extracted for each point along the modulation axis. The geometric analysis is performed using Fraunhofer diffraction and conjugate imaging …
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Optical display of the Airy function and transient wave propagation in a dispersive medium
… cubic amplitude transmittance, one can observe a Fourier transformed image of which intensity variation is identical to that of the Airy function. A lens system is used to achieve the Fourier transformation of the object which is a two-dimensional binary filter. A set of computer simulations are …
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Determining optimum imaging parameters for SWIFT: application to superparamagnetic iron oxides and magnetized objects.
… in MRI known as SWIFT, sweep imaging with Fourier transformation, has been shown to effectively image spins with both short and long transverse and longitudinal relaxation rates. It is desirable to have equations that accurately describe the signal of spins when excited by SWIFT; however …
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AN FFT SPECTRAL ANALYSIS FOR SYSTEM IDENTIFICATION
… spectral density functions by means of the fast Fourier transformation algorithm is discussed in terms of test procedure design, and accuracy considerations. The use· or the coherence function to obtain additional information as to the accuracy or the transfer function estimate is discussed and …
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In-plane vibrations of a transversely isotropic arch
… of solution are explored, namely the Laplace transformation, the method of particular solutions, and the eigensolution. The eigensolution is chosen as the the most efficient in terms of computer time and is the easiest to modify. The free vibration of the arch is explored and the natural …
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Applications of Fourier Domain Mode Locked lasers for optical coherence tomography imaging
… the spectrum of the interference signal in the Fourier domain. In "swept source OCT" implementations, the interference spectra are generated with a wavelength-swept laser and photodetector. Axial image lines are obtained via Fourier transformation of the spectra. Fourier domain techniques have …
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A Doppler Radar Lock-in Demodulation Algorithm for Machine Vibration Sensing
… necessitating line-down time. Conventional Fast Fourier Transformation based vibration analysis requires large amounts of data to achieve high spectral resolution necessary for fault detection especially with radio frequency sampling, which can be computationally too expensive for analysis. In …
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Ultra-wideband Radar Detection of Breathing Rate: A Comparative Evaluation
… two breathing rate derivation techniques: Fast Fourier Transformation (FFT) and Peak Detection. Results suggest great potential for the Walabot coupled with the FFT technique. However, the system requires further testing to address all of the research challenges. Overall, this work provides …
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Annual Modulation Measurement of the Low Energy Solar Neutrino Flux with the Borexino Detector
… function and analyzed with the Lomb-Scargle fast Fourier transformation in the search for significant periodicities between periods of 0.5 and 1.5 years. The search was performed in the energy window dominated by 7Be, [210; 760] keV, and 60-day bins in the case of the fit and 10-bins for the …
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Lévy Processes in Finance: Theory, Numerics, and Empirical Facts
… wird eine Charakterisierung der <br>Esscher-Transformation gegeben. Es wird eine effiziente Methode <br>vorgestellt, mit der man das Levy-Maß einer verallgemeinert <br>hyperbolischen Verteilung bestimmen kann. Als Korollar ergibt <br>sich hier eine Aussage über die Menge der zulässigen …
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Complex SANS SAXS data evaluation, simulation and interpretation with regard to statistical inference
… statistischen Inferenz-Ansätze auf die Indirekte Fourier Transformation (IFT) angewendet, um objektiv eine Freiform-Lösung zu erhalten, und moderne Methoden des Maschinellen Lernens (RVM, SVR, LASSO) werden benutzt, um eine stabilere Lösung zu ermitteln. Ein neues, selbst entwickeltes Programm …
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Phase Space Reconstruction using the frequency domain : a generalization of actual methods
… reconstructions such as time-delay, Hilbert-transformation, derivation and integration. The most used one is time-delay but all methods have special properties which are useful in different situations. Hence, every reconstruction method has some situations where it is the best choice. Looking …
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Miniature Fiber-Optic Farby-Perot Interferometer: Fabrication, Data Processing and Temperature Sensing Application
… from broadband fringes. The method combines Fast Fourier Transformation (FFT) with non-linear curve fitting of the entire spectrum. The new method successfully resolves the ambiguous problem for the direct fitting method and can provide higher resolution compared to the FFT method. Simulation on …
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Advanced Modelling of Helicopter Nonlinear Dynamics and Aerodynamics
… on the fuselage are examined by a Short Time Fourier transformation. The aerodynamic model uses blade element theory on the main-tail rotors. Hover, climb, descent and forward flight conditions are simulated and they allow the helicopter to follow certain trajectories. Finally, the ensuing …
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The measurement and characterization of surface topography
… surface can be obtained by applying the inverse Fourier transformation to a small group of selected coefficients. A catalogue of Fourier coefficients for constructing numerical models in this way is presented.
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Predicting protein-DNA interactions using statistical modeling and biophysical representations of high-throughput sequencing data
… are more likely methylated. We further perform fourier transformation and mutual information analysis to deduce the structure of chromatin impacting the interaction between DNA methyltransferases and DNA. Second, we identify conditions in which prime editor, a ribonucleoprotein that can target …
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