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 23 for “"energy cascade"”.
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Data-driven theoretical modelling of the turbulent energy cascade
Durch eine Modellierung der Energiekaskade gewinnt man wertvolle Einsichten in die Dynamik turbulenter Strömungen. In dieser Arbeit werden multiplikative Kaskadenprozesse untersucht und mit verschiedenen experimentellen Zeitreihen der Energiedissipation verglichen. Zur Berechnung der …
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Time-Lapse Acoustic Imaging of the Oceanic Energy Cascade
… semi-empirical parametrisation of internal wave energy. Comparison with diffusivities estimated from nearby hydrographic records and with previous measurements indicates that this method is robust. The analyses presented in this dissertation suggest that automated signal processing and …
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Symmetry Breaking and the Inverse Energy Cascade in a Plasma
… of symmetry breaking driving the inverse energy cascade in a quasi-two dimensional plasma system. The application of dynamic and rotating electrostatic bias as well as plans for applying turbulent feedback are discussed.
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Physical Insights of Non-Premixed MILD Combustion using DNS
… technology that can simultaneously improve the energy efficiency and reduce the pollutant emissions of combustion devices. It is characterised by highly preheated reactants and a small temperature rise during combustion due to the large dilution of the reactant mixture with products of …
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Exact coherent structures and non-universality in the direct cascade in two-dimensional turbulence
… often characterized by the presence of various cascades, which transport various quantities across length scales. This dissertation focuses on turbulence confined in two-dimensions, which has two cascades: an inverse (energy) cascade that moves energy towards increasingly larger scales, and a …
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Experiments in turbulent soap-film flows: Marangoni shocks, frictional drag, and energy spectra
… possible in two dimensions: the ``enstrophy cascade,'' for which the spectral exponent $\alpha=3$, and the ``inverse energy cascade,'' for which the spectral exponent $\alpha=5/3$. We find that the functional relation between the frictional drag $f$ and the Reynolds number Re depends on the …
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Necessary and Sufficient Conditions for the Transfer of Kinetic Energy at Asymptotically Large Reynolds Numbers
… and smaller versions of themselves to dissipate energy as heat. In the field of mathematical physics, turbulent flows are typically modeled using stochastic partial differential equations to model the apparent randomness of the turbulent flow. Moreover, from a physics perspective, this method …
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The Statistical Theory of Stationary Turbulence
… dominated, respectively, by a downward enstrophy cascade and an upward energy cascade. Finally, we contribute to the theory of wavelet transforms by demonstrating the existence of a Gibbs phenomenon for the continuous wavelet transform; the overshoot of the reconstructed function, at points of …
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On the Impact of Submesoscale Fronts on Mesoscale Eddies and Biological Productivity in the California Current System
… for the increased resolution. Further, the energy cascade of mesoscale eddies is better resolved contributing to the seasonal evolution of eddy kinetic energy. Finally, the biological productive band at the coast broadens, presumably driven by enhanced lateral transport of nutrients. The …
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Causal inference for complex systems and applications to turbulent flows
… approach in two turbulent-flow scenarios: the energy transfer across scales in the turbulent energy cascade and the interaction between motions across scales in a turbulent boundary layer. Our results show that, without accounting for redundant and synergistic effects, traditional approaches to …
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Characterization of low-frequency electric potential oscillations near the edge of a plasma confined by a levitated magnetic dipole
… of the fluctuations show that that an inverse cascade of energy is present at times in LDX. The cascade transfers energy from small spatial scale structures to large scale structures. The wavenumber spectrum is xc k-1.4 to cx k-25 at high wavenumbers, which encompasses the inverse energy …
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Oxidative chemical vapor deposition of semiconducting polymers and their use In organic photovoltaics
… OPV device performance. Promisingly, a ternary energy cascade device architecture is shown to more than double the OPV device performance to over 2%.
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Medium energy proton induced fission in uranium-238 and bismuth-209
Medium energy proton induced reactions, including fission, in 2380 and 209Bi have been studied. The inelastic interactions of protons with heavy nuclei have been described by a model in which the reaction proceeds in two steps. The first step is the fast cascade where a series of individual …
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Numerical study on internal flow structures of subaqueous density underflows and stratified open-channel flows
… to the inability of the RANS models to describe energy dissipation due to internal waves, a mechanism substantially different from the turbulent energy cascade theory. Analyses showed that the dimensionless settling velocity and shear Richardson number are the most dominant dimensionless …
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Energy loss and equilibration of a highly energetic parton in QCD plasmas
… or quark) traverses the medium, it loses its energy as a result of interactions with the medium. In this thesis, we describe the full in-medium kinetic and chemical equilibration of hard particles, using a linearized effective kinetic description of QCD at leading order. Since we include …
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Sensitized energy transfer for organic solar cells, optical solar concentrators, and solar pumped lasers
… for the end goal of achieving a lower cost solar energy generation. This thesis explores three new device architectures to overcome limited solar absorption in singlet-exciton-fission based solar cells and neodymium based LSCs. The process of singlet exciton fission is de-coupled from photon …
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Shear flow instabilities in stratified magnetohydrodynamics
… see that a weak magnetic field halts the inverse energy cascade, in a similar manner to how Balmforth (2002) showed that weak stratification does. At Pe,Rm»1, the weakly nonlinear model predicts boundary layers in the total temperature and magnetic potential fields at the inflection points of the …
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Design, Synthesis and Application of Cylindrical Polymer Brushes: From Nanostructures to Advanced Materials
… complex functional CPBs for light-harvesting and energy transfer, and utilized CPBs as templates for the synthesis of novel one-dimensional (1D) organic/inorganic hybrid nanostructures. The ‘grafting-from’ approach was chosen as the general method to synthesize well-defined CPBs with various …
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Data Analysis of an Unsteady Cavitating Flow on a Venturi-type Profile
… from the instabilities suggests a transfer of energy from the largest scales, fluctuating mean flow, to the smaller scales such as cloud cavitation and Kelvin-Helmholtz (KH) instability. It is demonstrated that the POD decorrelation of length scales yields inherently quasi-periodic time …
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Investigating Mesoscale, Submesoscale, and Mixing Ocean Dynamics in the Mozambique Channel Using Seismic and Simulation Datasets
… vortices, and wakes) facilitate the forward energy cascade. A lack of observations with sufficient spatial and temporal resolution however hamper understanding interior ocean dynamics. Better capturing mesoscale–submesoscale coupling at complex topography is particularly important as such …
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