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 24 for “"Averaged Model"”.
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Simulation of suspended sediment and contaminant transport in shallow water using two-dimensional depth-averaged model with unstructured meshes
… In 2008, Dr. Liu developed a two-dimensional model HydroSed which solves for 2D shallow water equations and sediment bedload transport equation at Hydrosystems Laboratory, UIUC. In this thesis, the author further modifi es and improves the HydroSedv1.0 model so that the model is able to deal …
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Modeling and numerical methods for power electronic devices
A scalable I-V model for latch-up in non-collinear PNPN devices is adapted from a previous model for collinear SCR devices. The model is applied to 14-nm FinFET test structures. Layout scaling trends for key latch-up metrics, such as holding and trigger voltage, are captured by the model in circuit …
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Techniques for handling clustered binary data
… for this fact (Little et al, 1997). Methods for modelling correlated binary data have also been discussed quite extensively. Among the many models which have been proposed for analyzing binary clustered data are two approaches which have been studied and compared: the population-averaged and …
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Nonlinear Dynamics and Interactions in Power Electronic Systems
… presented. A discrete nonlinear time-domain model is derived for open-loop DC-DC converters. This model is then extended for closed-loop regulator systems implementing any type of compensation scheme. The equilibrium solutions of the closed-loop system are calculated and their stability is …
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Nonlinear ion transport at high electric currents in shock electrodialysis and ion-intercalation memories
… contribution of this thesis to shock ED is the modeling of multicomponent ion separation. In addition, in this thesis, it is proposed that the CP in multiphase ion-intercalation materials can lead to phase re-distribution and can be used for non-volatile memories. A general phase-field model has …
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Numerical Models for Scour and Liquefaction Around Object Under Currents and Waves
… liquefaction, a three-dimensional numerical model for the sea bed response under free surface water waves is constructed. Free water surface is modeled by volume of fluid (VOF) method and water waves are generated by numerical wave-maker boundary condition. An iterative numerical scheme is …
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The biogeochemistry and residual mean circulation of the southern ocean
I develop conceptual models of the biogeochemistry and physical circulation of the Southern Ocean in order to study the air-sea fluxes of trace gases and biological productivity and their potential changes over glacial-interglacial timescales. Mesoscale eddy transfers play a dominant role in the …
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Non-Equilibrium Dynamics of Second Order Traffic Models
Even though first order LWR models have many limitations, they are still widely used in many engineering applications. Second-order models, on the other hand, address many of those limitations. Among second-order models, the inhomogeneous Aw-Rascle-Zhang (ARZ) model is well-received as its …
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Nonequilibrium thermodynamics of porous electrodes for lithium-ion batteries
… and costly experimentation or effective models. To be predictive enough to facilitate design, models must be based on underlying physics. However, battery models commonly make assumptions known to be false, such as describing phase separating materials with Fickian diffusion. In this …
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Digital control based on both small and large signal model based approaches for high switching frequency switched mode power converters
Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2024-05-01
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Bedforms and Gravity Underflows in Marine Environments
… was developed using a one-dimensional, layer-averaged model for conservative density currents (Ellison and Turner, 1959) that includes an additional equation for the layer-averaged turbulent kinetic energy (Parker et al, 1986). Similar methodology was also extended to the case of …
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Improved renewable energy power system using a generalized control structure for two-stage power converters
… system. The dissertation also presents a new modeling approach based on a modification of the subsystem-integration approach. The approach provides continuous-time small-signal models for all of two-stage power converters in a unified way. As a result, a modeling procedure is significantly …
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Modelling bottom stress in depth-averaged flows
The relationship between depth-averaged velocity and bottom stress for wind-driven flow in unstratified coastal waters is examined here. The adequacy of traditional linear and quadratic drag laws is addressed by comparison with a 2 1/2-D model. A 2 1/2-D model is one in which a simplified 1-D …
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LONGITUDINAL SOLUTE TRANSPORT IN OPEN-CHANNEL FLOW - A Numerical Simulation Study on Longitudinal Dispersion, Surface Storage Effects, Transverse Mixing, Uncertainties and Parameter-Transferring Problems
The longitudinal solute transport modeling is critical in river and stream water quality management, control, and the mitigation of hazardous riverine spills. One of the widely used "deadzone" model is the transient storage model (TSM). TSM is a significant improvement over the advection-dispersion …
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Interfacial Transport Phenomena of the Non-Wetting Phase in Porous Media: Applied to Polymer Electrolyte Fuel Cell Gas Diffusion Media
<p>Traditional methods for mathematical modeling of water transport in porous media lead to a sudden, sharp discontinuity in liquid saturation at the interface between two porous media of different properties. The goal of this study was to determine if this discontinuity is a physical phenomenon …
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Modelling bottom stress in depth-averaged flows
The relationship between depth-averaged velocity and bottom stress for wind-driven flow in unstratified coastal waters is examined here. The adequacy of traditional linear and quadratic drag laws is addressed by comparison with a 2 1/2-D model. A 2 1/2-D model is one in which a simplified 1-D …
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Nonlinear Analysis and Control of Standalone, Parallel DC-DC, and Parallel Multi-Phase PWM Converters
… analyses of power converters are based on averaged models, which ignore the fast-scale instability and analyze the stability on a reduced-order manifold. As such, validity of the averaged models varies with the switching frequency even for the same topological structure. The prevalent …
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A Novel High-Power High-Efficiency Three-Phase Phase-Shift DC/DC Converter for Fuel Cell Applications
… and exploits the solutions. A linearized ac model is derived and used to explain the ripple propagation. An active ripple reduction technique by the use of the current loop control is proposed. This active current loop control does not add extra converters or expensive energy storage …
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Channel Morphology and Riparian Vegetation Influences on Fluvial Aquatic Habitat
… temperature. Moving beyond one-dimensional (1D) averaged representations of fish habitat, this research explored the distribution of two-dimensional (2D) flow complexity metrics at the meso-habitat scale as explanatory variables for brook trout habitat preferences and as potential metrics to …
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Development and Validation of Non-Invasive Methods for the Identification of Patient-Specific Hyperelastic and Anisotropic Material Properties of Abdominal Aortic Aneurysms In Vivo
… metric ignores local tissue alterations from remodeling processes affecting the biomechanical properties of the vessel wall. These changes create heterogeneous deformations and vulnerable regions prone to rupture. Consequently, the diameter based criterion allows limited individual risk …
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