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 91 for “"mode decomposition"”.
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Wavelet-based Dynamic Mode Decomposition in the Context of Extended Dynamic Mode Decomposition and Koopman Theory
Koopman theory is widely used for data-driven modeling of nonlinear dynamical systems. One of the well-known algorithms that stem from this approach is the Extended Dynamic Mode Decomposition (EDMD), a data-driven algorithm for uncontrolled systems. In this thesis, we will start by discussing the …
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Multidimensional and multivariate empirical mode decomposition
Over the last decade, Empirical Mode Decomposition (EMD) has developed into a versatile tool for adaptive, scale-based modal decomposition. EMD has proven to be capable of decomposing multivariate signals with cross-channel mode alignment. However, the algorithms for envelope identification in …
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Dynamic mode decomposition with application to optimal control
… dynamics systems are central to a variety of modern engineering challenges. Direct numerical simulation of these processes is possible, but the high computational cost of these simulations is always an important consideration. Optimal control of these high-dimensional fluid dynamics problems …
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MID-ATLANTIC RIDGE (12~16oN) BATHYMETRIC ANALYSIS BY EMPIRICAL MODE DECOMPOSITION
… studies. This study applies 2-D Empirical Mode Decomposition (EMD) to simulate a similar 1D global study of mid-ocean ridges by Small (1994; 1998), but with fewer than 10 intrinsic mode functions (IMFs). With appropriate combination of IMFs, this study acquires not only similar D(x) and …
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Optimization Methods for Dynamic Mode Decomposition of Nonlinear Partial Differential Equations
Reduced-order models have long been used to understand the behavior of nonlinear partial differential equations. Naturally, reduced-order modeling techniques come at the price of either computational accuracy or computation time. Optimization techniques are studied to improve either or both of …
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Hypernasal Speech Analysis via Emperical Mode Decomposition and the Teager-Kasiser Energy Operator
… analysis methods of using a linear source model follow the premise that differences between normal and hypernasal speech can be distinguished by shifts or power changes in the formant frequencies and/or the widening (or narrowing) of the formant bandwidths. Such a premise, however, has not …
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An Integrated Compensation System Based on Empirical Mode Decomposition for Robust Noninvasive Blood Pressure Estimation
… suppressed using algorithms based on Empirical Mode Decomposition (EMD), which has the feature of removing unwanted noise components little effect on the phase or the frequency distribution of the measured signal. With motion artifacts, measurements show that the proposed algorithms considerably …
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Empirical mode decomposition applied to planar and volumetric velocity field measurements of a supersonic separated flow
… extensions of fast and adaptive empirical mode decomposition (FAEMD) are implemented on both three-component planar and volumetric velocity fields of a Mach 2.5 supersonic base flow which were obtained using particle image velocimetry. The resulting two-dimensional intrinsic mode functions …
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Damage Detection and System Identification using a Wavelet Energy Based Approach
… the physical parameters of an analytical model. First, the connection coefficients for the scaling function were developed for deriving the responses of the velocity and displacement from the acceleration responses. Next, defining the dominant sets based on the relative energies of the …
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Animal Motion Analysis and Approximation for Robotics
… system analysis techniques such as dynamic mode decomposition, extended dynamic mode decomposition, or even Koopman method to understand and compare the motion across different species. Thus, the goal of this thesis is to further develop the methods mentioned above to analyze and …
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Characterization of Dynamic Structures Using Parametric and Non-parametric System Identification Methods
… and non-parametric approaches based on how to model dynamic systems. The objective of this study is to characterize the dynamic behaviors of two realistic civil engineering structures in SFS configuration and subjected to impact loading by comparing different parametric and non-parametric …
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Data-Driven Modeling of Tracked Order Vibration in Turbofan Engine
… no representative and efficient physics-based models with the adequate fidelity to perform vibration predictions in aircraft engines, given various parametric dependencies existing among different attributes such as temperature, pressure, and external conditions. This gap in research is …
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Phase Space Structure of Disequilibrium in the Milky Way
… structures, using a combination of analytic modeling, simulations, and Dynamic Mode Decomposition to study explicitly their formation and evolution in the presence of self gravity. In doing so, we have demonstrated the first application of DMD to collisionless, self-gravitating systems. We …
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Data-driven system identification of strongly nonlinear modal interactions and model updating of nonlinear dynamical systems
… the calibration and validation of computational models. When a model fails to reproduce measurements, engineers must identify and incorporate the unmodeled and/or uncertain dynamics to reconcile theoretical prediction and experimental observation. While linear identification tools are …
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Towards Multiclass Damage Detection and Localization using Limited Vibration Measurements
… response). Over the last few decades, various model-based and time-frequency methods have shown great promises for damage identification and localization. However, the existing methods are unable to perform satisfactorily in many situations, including the presence of limited sensor measurements …
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Large eddy simulations of premixed turbulent flame dynamics : combustion modeling, validation and analysis
… conditions are some of the key requirements of modem-day combustors. To achieve these objectives, lean premixed flames are generally preferred as they achieve efficient and clean combustion. A drawback of lean premixed combustion, however, is that the flames are more prone to dynamics. The …
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Description of Coherent Structures in the Atmospheric Boundary Layer By Model Reduction of the Surface Pressure
… of these features suggests description by model reduction. To this end, an array of pressure transducers was deployed on the ground at Reese Technology Center in Lubbock, Texas, and the pressure fluctuations were recorded over nearly two diurnal cycles. A program for computation of the …
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A dynamical systems approach to the study of local phenomena in fluid flows
… are Koopman eigenfunctions (through dynamic mode decomposition) and spectral submanifolds. Due to their immense popularity, both of these techniques have been studied extensively, to the point that most aspects regarding their implementation are now fully fleshed out. However, there is one …
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Application of Koopman Operator Theory to Legged Locomotion
… work, we present a linearized simple walking model using Koopman Operator Theory, and its usage in Linear Model Predictive Control (L-MPC). Various walking and contact models were evaluated, but ultimately the rimless wheel was selected due to its inherent stability and low dimensionality, and …
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