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 82 for “"discrete Fourier transform"”.
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PAPR reduction in OFDM communications with generalized discrete Fourier transform
The main advantage of Generalized Discrete Fourier Transform (GDFT) is its ability to design a wide selection of constant modulus orthogonal code sets, based on the desired performance metrics mimicking the engineering specs of interest. One of the main drawbacks of Orthogonal Frequency Division …
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Generalized discrete Fourier transform with non-linear phase : theory and design
Constant modulus transforms like discrete Fourier transform (DFT), Walsh transform, and Gold codes have been successfully used over several decades in various engineering applications, including discrete multi-tone (DMT), orthogonal frequency division multiplexing (OFDM) and code division multiple …
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Low-power discrete Fourier transform and soft-decision Viterbi decoder for OFDM receivers
The purpose of this research is to present a low-power wireless communication receiver with an enhanced performance by relieving the system complexity and performance degradation imposed by a quantization process. With an overwhelming demand for more reliable communication systems, the complexity …
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Advanced Orthogonal Frequency-Division Multiplexing Systems with Cyclic Prefix-Less Multiple-Input and Multiple-Output Discrete Fourier Transform Spreading and Unmanned Aerial Vehicles-Assisted Cyclic Postfixed Windowed Schemes
… MIMO OFDM System. It is based on incorporating Discrete Fourier transform (DFT) spreading, signal discrimination with Walsh-Hadamard coding, and PAPR reduction with Tukey (tapered cosine) time-domain windowing techniques. This combination of mechanisms provides an effective combination of …
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A method for the spatial functionalization of the dynamic response of a structure with structural stability considerations
… and edge-median filter algorithm followed by a Discrete Fourier Transform/low-pass spatial frequency domain filter/Inverse Discrete Fourier Transform algorithm is used to reduce the effect of errant data recorded by the LDV data acquisition system. A means of evaluating the performance of this …
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Fast algorithms for DFT and convolution
… representation. The recent Ideas of converting Discrete Fourier Transform to convolution and Implementing convolution efficiently, have been combined to give two algorithms viz. Nested Fourier Algorithm (NFA -- using linear multidimensional map) and Index Fourier Algorithm (IFA using a …
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Segmented Mirror Telescope model and simulation
… needed for future spacebased telescopes. A discrete Fourier transform wavefront reconstruction technique developed at Lawrence Livermore National Laboratory is discussed in this thesis as applied to a hexagonal aperture. A Fourier domain implementation of a spatial-frequency modal controller …
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Spectral analysis of random number generators
… of pseudorandom number generators using the Discrete Fourier Transform. We will show how the concept of a random process can be used in a representation for random discrete time signals. Using this concept, we have focused on the mathematical representations of the spectral analysis of a fair …
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Numerical and Harmonic Analysis of Simplex Number Parity
… decomposition result. We then introduce the discrete Fourier transform to construct the periodic parts of each index sequence, enabling the development of explicit forms for the ordered even d-simplex numbers for any finite dimension.</p>
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Sparse representation for audio noise removal using zero-zone quantizers
… of quantization can be applied on orthogonal transforms to remove the unwanted or redundant signal. Transforms reveal structures and properties of a signal and hence careful application of a zero zone over the transform coefficients leads to noise removal. In this thesis, such quantizers are …
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An Application of Spectral Translation and Spectral Envelope Extrapolation for High-frequency Bandwidth Extension of Generic Audio Signals
… an application of the modulation theorem for discrete Fourier transform to regenerate the missing high-frequency end of the signal spectrum with a linear-regression-driven approach to shape the spectral envelope for the regenerated band. The results are graphically and acoustically compared to …
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Form as meter: metric forms through Fourier space
The Discrete Fourier Transform, which was initially mentioned in the music theory domain by David Lewin, is an analytical tool developed by Ian Quinn, and later expanded by theorists such as Jason Yust, William Sethares, and Andrew Milne. Though it was originally designed for pitch-class spaces, …
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Fast Phase Retrieval: A Robust and Efficient Multidimensional Phase Retrieval Algorithm
… the object given only the magnitudes of its discrete Fourier transform. We present numerical evidence that the algorithm additionally succeeds quite often for non-Schwarz objects. We also present a set of measurement matrices for which the algorithm is guaranteed to recover any object. We …
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METHODS COMPARISON ON FLOW MODEL CONSTRUCTION AND PARAMETER ESTIMATION
… of nonlinear Dynamics (SINDy) and Non-Uniform Discrete Fourier Transform (NUDFT) are compared over their ability to find the expression of unknown systems or to estimate key parameters of a dynamical system. Multiple tasks with different purposes are created to test the performances of these …
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NONUNIFORMLY AND RANDOMLY SAMPLED SYSTEMS
… missing data using bandlimiting assumptions and discrete Fourier transform techniques is developed. Representation and analysis of randomly sampled linear systems with independent and identically distributed sampling intervals are studied. The mean, and the mean-square behavior of a …
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Performance evaluation of nonlinear satellite link by computer simulation
… the simulation procedure are real-valued and are transformed back and forth between time and frequency domains depending on the necessity by the Fast Fourier Transform (FFT) or Inverse Discrete Fourier Transform (IDFT). The simulation result represented as average Bit Error Rate (BER) gives the …
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Diagnosis of operational changes in microelectromechanical systems via fault detection
… Analysis of the residual was conducted using a discrete Fourier transform (DFT). Two common MEMS research devices, the lateral comb resonator and parallel plate actuator, are used to demonstrate theoretically and experimentally the ability of the fault detectors to identify induced faults in …
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Improving Mobile SOC's Performance as an Energy Efficient DSP Platform with Heterogeneous Computing
… concepts, several implementations of both the discrete Fourier transform (DFT) and the fast Fourier transform (FFT) are tested across devices. The results show both improvement in performance and energy efficiency on many devices compared to traditional Java implementations and indicate that …
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Mathematical methods for non-intrusive load monitoring
The calculation of the Discrete Fourier Transform (DFT) of a discrete time signal is a fundamental problem in discrete-time signal processing. This thesis presents algorithms that use methods from number theory and algebra to exploit additional constraints about a signal to aid in the calculation …
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Resistive Companion Dynamic Phasor Networks and Phasor to Time Domain Network Coupling
… sources, modified nodal analysis (MNA), and a discrete Fourier transform (DFT) phasor estimation. A coupling device using this technique is implemented in Virtual Test Bed (VTB). The accuracy and stability of the method is verified with two test systems, including a system consisting of a …
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