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 37 for “"Semi-analytical model"”.
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Semi-analytical model of ionization oscillations in Hall thrusters
… The first part of this thesis details a steady model of the ionization region in a Hall thruster that finds existence criteria for the steady solution under the hypothesis that the steady limits match the smooth sonic passage limits. Operation outside these limits would correspond to unsteady …
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A Semi-analytical Model for Nonlinear Elliptical Inclusions with Spherical Eigenstrains
… in 1957, John D. Eshelby provided a fully-analytical solution for the stress and deformation fields induced by an incompatible ellipsoidal inclusion embedded within an infinite matrix. Over the past six decades, his theory, which considers linearly elastic materials, has been essential in …
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Semi-Analytical Model to Study Vibrations of High-Speed, Rotating Axisymmetric Bodies Coupled to Other Rotating/ Stationary Structures
… and stationary bodies motivates this work. A semi-analytical model is developed for high-speed, compliant, rotating bodies. Exploiting the axisymmetry of the rotating body, the developed semi-analytical model only discretizes the two-dimensional radial cross-section; Fourier series are used in …
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Full waveform inversion of ultrasonic phased array data for the tomographic reconstruction of heterogeneous media for NDT
… parametrise the wave speed map; a bespoke semi-analytical model that encompasses the data within an ultrasonic A-scan while being computationally efficient; a bespoke objective function toquantify how well the semi-analytical model compares to the observed data; and a Bayesian framework, …
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Finite difference time domain simulation of subpicosecond semiconductor optical devices
… numerical method to simulate a subpicosecond semiconductor optical switch is developed in this research. The problem under studying involves both electromagnetic wave propagation and semiconductor dynamic transport, which is a nonlinear phenomenon. Finite difference time domain (FDTD) …
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Smart passive adaptive control of laminated composite plates (through optimisation of fibre orientation)
… induced twist, there is a need for a modified model to predict the behaviour of laminated composites. A composite normally consists of two materials; matrix and fibres. Fibres can be embedded in different orientations in composite lay-ups. In this research, laminated composite models subject to …
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Numerical and experimental investigation of shakedown in evolving non-Hertzian rolling contact
… to near Hertzian by the end of this stage. A semi-analytical model is therefore employed to perform the contact analysis. Special elements are employed near the surface discontinuities within the contact area to resolve singularities. The contact area is observed to change from elliptic to a …
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Modeling the impact of petroleum mixtures released from railroad tank car accidents on groundwater contamination and cleanup times
… a number of thermodynamic and empirical models estimating mixture properties required to predict the migration and entrapment in the subsurface of nonaqueous phase liquids released due to railroad tank car accidents. The properties include density, viscosity, surface and interfacial …
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Modeling and Characterization of Structural, Thermophysical, and Dynamical Evolutions of Small Bodies in the Solar System
… condition through the development of a semi-analytical model based on granular physics, offering rapid yet accurate insights into asteroid reshaping and mass-loss processes. Second, a 3-dimensional thermophysical model is developed to better characterize the thermal conditions of …
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Photon reconstruction for the H.E.S.S. 28 m telescope and analysis of Crab Nebula and galactic centre observations
… 28 m telescope. The method is based on a semi-analytical model of electromagnetic particle showers in the atmosphere. The properties of cosmic γ-rays are reconstructed by comparing the camera image of the telescope with the Cherenkov emission that is expected from the shower model. To …
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The clustering of galaxies in hierarchical galaxy formation models
… galaxy formation and evolution. The GALFORM semi-analytical model is the theoretical approach we used to model galaxy formation. We start by studying the luminosity dependence of galaxy clustering which is measured accurately in the local Universe. We have compared the clustering predictions …
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Nanoengineered surfaces for advanced thermal management
… liquid separation into several layers. An analytical model based on surface energy was developed to explain the phenomenon and was validated by experiments on additional tailored pillar geometries. Subsequently, a semi-analytical model was developed to predict the propagation velocity based …
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Development of Flexible Pressure and Strain Sensors for Electronic Skin Applications
… high sensitivity, development of a comprehensive analytical model capturing their pressure sensing performance, and fabrication of large strain flexible strain sensors with high stretchability and sensitivity and low hysteresis. Therefore, this work attempts to address some of these issues and …
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Enhanced Ambient Heat Rejection in Passive Thermal Management Systems
… test bench is used to validate the numerical model experimentally. It is shown that ionic wind can increase the heat removal rate by up to 100% as compared to natural convection only. The second cooling enhancement technology considered is the addition of a chimney on top of the heat sink to …
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Modelling of low frequency muffler based on acoustic black hole effect
… underlying this research work. Firstly, a semi analytical model has been formulated for an open expansion chamber, embodied by the muffling section. Plane wave radiation incident through inlet end of the muffler, is made to undergo impedance matching while traversing through the …
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A fundamental approach to predicting mass transfer coefficients in bubble column reactors
… operating costs. On the other hand, attempts at modelling and simulation are complicated by lack of understanding of hydrodynamics and mass transfer characteristics. This complicates design scale-up and industrial usage. Many studies and models have attempted to evolve understanding of the …
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Pressure Shielding Mechanisms in Bio-Inspired Unidirectional Canopy Surface Treatments
… fluctuations up to nearly twice the height. Semi-analytical model is developed to predict surface pressure spectra in a wall-jet and canopy flow. The rapid term model shows that the inflection in the streamwise mean velocity profile is the most dominant source of surface pressure …
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Functionalized Shape Memory Alloy Microfilament Twisted Yarn Structures
… Key parameters function as inputs in a semi-analytical model that was derived from traditional yarn and SMA material models to predict the performance of SMA microfilament twisted yarns. The model accounts for superelastic recovery, shape memory actuation, and dynamic contraction …
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Constraining the Major Merging History of Massive Galaxies: A Comprehensive Analysis of Close Pairs and Tidal Features Using Empirical and Simulated Data
… mock light cone data from the leading SantaCruz Semi-Analytical Model (SAM), we systematically analyze the impact of different observational effects on the measurement of close-pair frequency and provide detailed statistical corrections to account for them. We also developed a new public software …
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Preliminary design tools in turbomachinery: Non-uniformly spaced blade rows, multistage interaction, unsteady radial waves, and propeller horizontal-axis turbine optimization
… starting point for the later CFD analyses. Four analytical/semi-analytical models are developed in this study: 1) a generalized flat plate cascade model for investigating the unsteady aerodynamics of a blade row with non-uniformly spaced blades; 2) a multistage interaction model for investigating …
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