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 33 for “"Modal Decomposition"”.
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Analysis of Ship Airwakes Using Modal Decomposition
… of the TR-PIV measurements were performed using modal decomposition, and the modes were decomposed further based on the frequency contents of their time dynamics. This approach allowed an inspection of the individual scales of the airwake and provided a quantitative estimate of energy …
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Analyzing modal decomposition data of finite antenna arrays
… dependency on parametric simulations, we study a modal decomposition of the array currents. In particular we use characteristic mode analysis (CMA) which produces an indexed set of “simpler” eigencurrents, and eigenvalues that dictate the energy storage properties of the modes. These modes are …
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Acoustic mode coherence in the Arctic Ocean
The dual issues of modal decomposition for tonal sound fields and the temporal coherence of the modal amplitudes are investigated for the case of the central Arctic sound channel at very low frequencies (15-80 Hz). A detailed study of the Arctic modal structure for these frequencies reveals the …
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Crosstalk mitigation of high-speed interconnects using modal signaling
… this research is to explore the application of modal decomposition of coupled transmission lines to crosstalk mitigation of high-speed interconnects, in particular far-end crosstalk (FEXT), which is the dominant noise source for modern single-ended memory links. Special attention is devoted to …
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Wavelets Based on Second Order Linear Time Invariant Systems, Theory and Applications
… instantaneous frequency identification and modal decomposition of LTI Multi-Degree of Freedom (MDOF) systems and it showed better results than the Short-time Fourier Transform (STFT) and the other harmonic wavelets used in time-frequency analysis. The modal decomposition is applied for modal …
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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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Active, Passive and Active/Passive Control Techniques For Reduction of Vibrational Power Flow in Fluid Filled Pipes
… flow in fluid filled pipes. Circumferential modal decomposition and measurements of vibrational power carried by individual wave types were carried out experimentally. The importance of dominant structural bending waves and the need to eliminate them in order to obtain meaningful experimental …
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Parametric spatial modal analysis of beams
Modal analysis is the experimental characterization of the dynanlical behavior of a structure. Recent advances in laser velocimetery have made available to the experimentalist a rich, new source of vibration data. Data can now be obtained from many different spatial locations on a structure. A …
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Tomographic Reconstruction of Wavefront Aberrations using Multiple Laser Guide Stars
… extremely large (30 m class) telescopes (ELT). Modal decomposition of wavefront phase using Zernike polynomials is a widely used technique in adaptive optics (AO) research. However, this approach breaks down with the large number of degrees of freedom required by ELTs.This research proposes the …
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Comparative Evaluation of Vorticity Transport Modeled Distortions and High-Fidelity ANSYS Solutions Using Modal Assurance Criterion
… Bulk Swirl, Twin Swirl, and Quad Swirl. Modal decomposition through singular value decomposition (SVD) is performed on the resulting in-plane velocity profiles for both the ROM and high-fidelity RANS simulations. The accuracy of the ROM is assessed through both conventional error analyses …
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Internal tide generation by tall ocean ridges
… ridge in a uniform density stratification. A modal decomposition technique was developed to characterize the structure of the experimental wave fields generated by 2D model topographies in a specially configured wave tank. The theory accurately predicts the low mode structure of internal …
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Investigation of a compact acoustic source array for the active control of aircraft engine fan noise
… field established in the duct cross-section. Modal decomposition was applied to the data. It was found that the dominant acoustic modes in the duct are those whose cut-on frequencies were near the frequency of excitation.
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Acoustic prediction and noise control of a refrigeration compressor
… are investigated. For the acoustic prediction, a modal decomposition approach is used. To this end, a boundary element model of the shell is created, and it is used to compute the modal radiation efficiency curves of the shell. These radiation efficiencies are then used in conjunction with the …
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Modal analysis of vertical array receptions for the Heard Island Feasibility Test
… source nearly 18,000 km away. By determining the modal structure of the received transmissions, it is possible to characterize the physics of such long range propagation. This thesis focuses on the determination of the modal, or vertical, structure of the signal. It was necessary to first develop …
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Numerical Analysis of Human-Informed Topology Optimized Lateral-Load-Resisting Systems of Tall Buildings under Seismic Excitation
… algorithm which optimizes designs under a sum of modal compliances formulation, similar to how structures are analyzed in seismic codes. The designs are evaluated quantitatively, comparing natural periods, modal displacements, sum of modal compliances using modal decomposition, as well as …
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Modelling the perception of percussive low frequency instruments in rooms
… effects and methods of controllingand mitigating modal behaviour are a well researched topic. However, despite this, agap between objective metrics and subjective results is still prevalent, thus resultingin a limited understanding of perceived bass quality.Previous work has suggested a group of …
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Experimental Damage Diagnosis of a Model Three-Story Spatial Frame
… metal frame building was constructed. Using Star Modal software, dynamic structural properties were obtained from modal decomposition on experimental tap test responses. The natural frequencies and mode shapes of the structure established an as-built baseline for comparison to ten other scenarios …
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A Quadratic Non-Linear Elasticity Formulation for the Dynamic Behaviour of Fluid-Loaded Structures
… larger displacements. By extending the standard modal decomposition technique for linear structural analysis, the governing equations and boundary conditions are updated to account for the leading-order non-linear terms and a new modal formulation with quadratic modes is derived. The quadratic …
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Structure Borne Noise Analysis Using Helmholtz Equation Least Squares Based Forced Vibro Acoustic Components
… radiation were factorized using singular value decomposition to obtain orthogonal basis known here as the forced vibro-acoustic components (F-VACs). The F-VACs enables one to identify the critical vibration components for sound radiation in a similar manner that modal decomposition identifies …
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Open-loop and closed-loop trailing-edge separation control on a natural laminar flow airfoil
… unsteady surface pressure measurements. Adaptive modal decomposition methods were used to identify the frequencies of natural instabilities in the flowfield in real-time. A proportional controller was designed to automatically control the blowing amplitude by estimating the state of the flow and …
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