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 494 for “"length scale"”.
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Length-Scale Effects on Nano-Scale Materials Behavior
… cannot explain the elastic behavior at the nano-scale and we propose a mechanism based atomic-scale interactions. (3) In-situ TEM tests show that below a transitional length-scale (50 nm grain size for aluminum), dislocations cease to exist in the grain interiors. Absence of both dislocation and …
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Multi-Length Scale Modeling of Rubber Tribology For Tire Application
… interface. Past research studies developed multiscale techniques for estimation of friction coefficient due to hysteretic losses from internal damping of the rubber material because of oscillation from surface undulations. Later, contact mechanics models developed using Hertzian technique or …
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On the length-scale and location of channel nucleation in directional solidification
… studied, is shown to be a function of the length scale D/ V, where it is shown that channeling can be turned on or off simply by changing this length scale. This work also validates a finite element model of dendritic solidification by comparing predicted results to data resulting from …
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Relaxation dynamics in borate glass formers probed by photon correlation at the microscopic and macroscopic length scale
X-ray photon correlation is used to probe the dynamics of the strong glass former boron trioxide and of a series of alkali borate glasses, (M2O)x(B2O3)1-x where M is the alkali modifier (M=Li, Na and K). The decay times τ of the obtained correlation functions in B2O3 are consistent with visible …
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The role of molecular length scale on the viscoplastic response of amorphous polymer nanofibers in the glassy state
… particularly strong at the micron and submicron scales. The majority of existing literature on the mechanical properties of ultra-small volumes of polymers in their glassy state focuses on ultra-thin films and is limited to small deformations and the viscoelastic regime. Experiments with …
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Surface-enhanced Raman and surface plasmon resonance measurements of Case II diffusion events on the nanometer length scale
… of SERS-active planar films implanted in $\mu$m-scale polymer films. The use of Au rather than Ag metal-island films is shown to eliminate spectral interference resulting from photolytic degradation reported in typical SERS studies of glassy polymers. A sample probe consisting of an Au metal film …
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Effects of Freestream Turbulence, Turbulence Length Scale, and Reynolds Number on Turbine Blade Heat Transfer in a Transonic Cascade
… high freestream turbulence intensity, turbulence length scale, and exit Reynolds number on the surface heat transfer distribution of a turbine blade at realistic engine Mach numbers. Passive turbulence grids were used to generate freestream turbulence levels of 2%, 12%, and 14% at the cascade …
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Using nuclear magnetic resonance and the dipolar field to study structural properties of two-phase liquid systems
… of diamagnetic substances. The extraction of length scale information in liquid NMR spectroscopy is largely limited to sizes below the diffusion length (^ 50 microns). Breaking translational symmetry using the nuclear dipolar field imparts a scale dependence, and provides a means of measuring …
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Tropical cyclone size in observations and in radiative-convective equilibrium
… parameter given by the ratio of the storm radial length scale to the parameterized eddy radial length scale. The relevant storm length scale is shown to be the ratio of the potential intensity to the Coriolis parameter, matching the prediction for the "natural" storm length scale in prevailing …
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Simulation and modeling of magnetically-assisted impaction coating (MAIC) process for dry particle coating
… understand the processes happening at multiple length and time scales in magnetically assisted impaction coating process. The smallest length scale is of the order of the molecular size and is important because during collisions the molecules rearrange themselves to form a semi-permanent bond …
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The effects of freestream turbulence on the drag of a sphere
… of freestream turbulence intensity and integral length scale as freestream turbulent parameters on the drag coefficient of a solid sphere were experimentally investigated in a closed-circuit wind tunnel. The Reynolds number, Re = Ud/ν, was varied from 2.2×104 to 8×10 4 by using spheres of …
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Ligand shell morphology of water-soluble mixed-monolayer protected gold nanoparticles
… consist of particles that have a characteristic length scale less than 100nm. They are on a similar length scale as many biological elements, so it is fitting that they are being used increasingly in biological systems for a variety of applications. Interesting properties of water-soluble metal …
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Flow resistance corrections for physical models using unit flowrates
… prototype channel characteristics at the model scale. The scale for a given physical model may be characterized by length-scale factor, given by the relationship of prototype to model geometry. Models that have a large length-scale factor are known to introduce errors associated with …
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A Biomimic Self-healing Shape Memory Polymer Based Syntactic Foam for Smart Structural Composites
… The objective was to self-heal structural-length scale damage in an autonomous, efficient, timely and repeatable manner at the molecular-length scale. Self-healing is achieved through a novel two step close-then-heal (CTH) self-healing scheme, designed to mimic the natural biological …
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Numerical investigation of the influence of elevated turbulence levels on the cooling effectiveness of an anti-vortex hole geometry
… with varying turbulence intensity and length scale using the k-o SST turbulence model. Both steady and unsteady results were considered in order to investigate the effects of freestream turbulence intensity and length scale on this novel anti-vortex hole (AVH) concept. The AVH geometry …
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Phase field modeling of dynamic brittle fracture at finite strains
… describes the fracture process. An original length scale is used to govern the diffusive approximation of sharp cracks. This method further employs a degradation function to account for the loss of the material stiffness during fracture by linking the phase field to the body’s bulk energy. To …
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Atomistic engineering of fluid Structure at the fluid-solid interface
… are especially pronounced when the confining length scale is comparable to the fluid's internal (molecular) length scale. Elucidating the physical principles governing nanoconfined fluids is critical for many pursuits in nanoscale engineering. In this thesis, we present several theoretical and …
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Information Theory Analysis of the Solar Wind Magnetic Structures for Space Weather Prediction
… that span multiple temporal, spatial, and energy-scales. The solar wind is a highly structured, multi-scale, evolving plasma and consists of coronal mass ejections (CMEs), stream interaction regions (SIRs), expanding flux tubes (Borovsky, 2008), and interplanetary magnetic field (IMF) …
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Steady and unsteady visco-resistive reconnection in the presence of the Hall effect
… In Chapter 3, we search for a visco-resistive length scale in reconnection solutions. This is demonstrated in reconnective annihilation and a quasi-one-dimensional series expansion. We find that the visco-resistive length scale appears organically unless a specific geometry is chosen. Upon …
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Imaging Resolution of the 410-km and 660-km Discontinuities
… as well as P-to-S converted waves by varying the length scale of discontinuity topography in the transition zone. We show that wavefront healing effects are significant in broadband receiver functions. For example, at a period of 10 to 20 seconds, the arrivaltime anomaly in P-to-S converted waves …
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