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 22 for “"atomistic model"”.
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Atomistic model of void nucleation and growth during electromigration
… To help gain a better understanding of the atomistic processes involved in void formation under electromigration conditions we have used the Embedded Atom Method (BAM) to determine the structure and formation energies of small voids (up to 20 vacancies) in aluminum and copper both in bulk …
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Nanomechanics model for static equilibrium
This study presented a computational technique to model and simulate atomistic behavior of materials under static loads. Interatomic potential energy was used to maintain equilibrium among atoms under static loads and constraints. In addition, the atomistic model was coupled with the finite element …
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Multi-scale modelling of atomic layer deposition
… of the deposited film. Using multi-scale modelling of ALD, the kinetics of reactions at the growing surface is connected to experimental data. In this thesis, we use density functional theory (DFT) method to simulate more realistic models for the growth of HfO2 from Hf(N(CH3)2)4/H2O and …
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A comparison of three gadolinium based approaches to cancer therapy
… superimposed Auger electron tracks over an atomistic model of mammalian chromatin fiber and tracked resulting OH, H, and eaq radicals to determine strand breaks.
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Continuum and Atomistic Simulation of Electrically-Mediated Flow Through Nanometer Channels
… flow by performing a detailed comparison between atomistic and continuum simulations. Our results indicate that the molecular nature of the ion and water are important factors influencing the ion concentrations, velocity profiles and other fluid characteristics in nanochannels. As the continuum …
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Multiscale hybrid simulation of brittle fracture
… taking place near the crack tip with a classical atomistic model that captures the long-range elastic relaxation. The ‘Learn on The Fly’ technique is used to couple the quantum and classical models, allowing accurate quantum forces to be combined with classical forces using a simple adjustable …
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Hybrid atomistic-continuum formulations for gaseous flows
Hybrid atomistic-continuum formulations allow the simulation of complex hydrodynamic phenomena at the nano and micro scales without the prohibitive cost of a fully atomistic approach. This is achieved through a domain decomposition strategy whereby the atomistic model is limited to regions of the …
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Vibrational dynamics in water from the molecule's perspective
… Computer simulations of empirical models, however, offer explicit microscopic detail but must be adapted to include a quantum mechanical vibration. I have developed methods in computer simulation to relate spectral fluctuations of the OH stretch in liquid D₂0 to explicit microscopic …
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A new framework for the interpretation of modulated martensites in shape memory alloys
… martensites, this Modulated Martensite Mixture Model is capable of accurately predicting the energy, lattice constants, and structural details of an arbitrary modulated martensite phase. This is demonstrated by comparing the Modulated Martensite Mixture Model predictions to computational results …
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Size-dependent mechanical properties of beta-structures in protein materials
… MD simulations, the first representative atomistic model for spider silk is proposed. The computational, bottom-up approach predicts a multi-phase material with beta-sheet nanocrystals dispersed within semi-amorphous domains, where the large-deformation and failure of silk is governed by …
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Self -assembly on strained metallic interfaces, and, Novel collective excitations on metal surfaces
… experimental observations are explained via an atomistic model, which is based on first-principles interaction parameters. I have found that the self-assembly process is driven by stress relaxation in the Ag film.</p><p>While the first part of my thesis is focused on the structural properties of …
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Computational modelling of polymer network formation
… on the First Shell Substitution Effect (FSSE) model of polymerisation. The FSSE framework was used to evaluate a coarse-grained simulational method, benchmarked against a fine-grained, atomistic model that was constructed using Reactive Molecular Dynamics (RMD). A modified version of RMD was …
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Structural and mechanical properties of intermediate filaments under extreme conditions and disease
… as well as disease states. We use a full atomistic model and study its response to mechanical stresses. Learning from the mechanical response obtained from atomistic simulations, we build mesoscopic models following the finer-trains-coarser principles. By using this multiple-scale model, …
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Molecular structure, hierarchical assembly and stimuli-responsive mechanics of tropoelastin and elastin biomaterials
… its detailed features. Solving tropoelastin's atomistic structure is key to characterizing elastin's complex biological function, disease-related mechanisms associated with mutations therein, and assembly process, to replicate natural function upon impairment. From the materials perspective, …
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Development of a Multiscale Atomistic Code to Investigate Self-Organized Pattern Formation Induced by Ion Irradiation
… Dynamics/kinetic Monte Carlo) multiscale atomistic model is developed to elucidate these unknown issues. This model uses the crater functions, which are obtained by MD simulations, to model the prompt mass redistribution due to single-ion impacts. Defect migration, which is missing in …
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Structural heterogeneity in silk fibers and its effects on failure mechanics and supercontraction
… a shear flow at natural pulling speeds is modelled and the secondary structure transitions as well as shear stresses in the silk protein chains are determined. It is shown that under shear stresses beyond the elastic regime, silk undergoes an [alpha] -- [beta] transition in the spinning …
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Computational Modelling of Nanoscale Interactions for Nanophotonics and Biosensing
… computational methods in photonics and molecular modelling. In the first section, we investigate biosensor signals from the catalytic cycle of Adenylate Kinase (AdK); a large protein with more than 3000 atoms. We assume that the AdK molecule is situated in a region of high field intensity …
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Quantitative analysis of nanoscale order in amorphous materials by stem-mode fluctuation electron microscopy
… as well as in development of data analysis and modeling methods. The use of the STEM mode in FEM enables detection and correction of some experimental artifacts, and advanced methods such as variable resolution FEM (VR-FEM) afford some quantitative information on the length scale of the order. …
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Ultrashort laser pulse-matter interaction: Fundamentals and early stage plasma dynamics
… A two-dimensional comprehensive hydrodynamic model for USLP ablation of metals and semiconductors is developed in this study. The model comprises a two-temperature model and a hydrodynamic model supplemented with a quotidian equation of state model, considering the relevant multiphysical …
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Spin cluster expansion approach to the interplay between short-range order and interstitial atoms in austenitic stainless steels
… between SRO and interstitials, thermodynamic modeling approaches are essential for sampling alloy configurations. The cluster expansion (CE) method, combined with Monte Carlo (MC) simulations, provides a powerful computational framework for studying the thermodynamic properties of alloys. We …
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