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Description
When, in 1958, Disney aired a program titled “Magic Highway USA” featuring autonomous vehicles directed by punch-cards, few would have predicted touchscreen reprogrammable devices. None could have foreseen a battery powered car capable of fully autonomous operation and a zero to sixty mph acceleration in 1.9 seconds. The 21st century has proven to be one of exponential technological advancement and stunning innovation, with few case studies more obvious than that of the progression of autonomous vehicle (AV) technology. Advances in transportation technology and robotics have, throughout history, pointed to the eventual development of fully autonomous vehicles; however, it is only within the last 10 years that innovation has met determination to leapfrog AV development to its current state. As this technology has developed, society has begun to realize its extensive social implications, both positive and negative, from extending mobility to the impaired to reducing the need to fill jobs in the transportation industry. With progress comes new challenges and as planners strive to get ahead of the pace of AV innovation, it is becoming increasingly apparent that questions of data security, privacy, regulation, and liability must be quickly addressed. Some also question the economic feasibility of AV and suggest that, unless new economic models are developed around the transportation industry, there is a significant risk of increased societal strain as a result of digital and economic inequality. As a consequence, industry, academia, and policy have all emerged to direct, manage, and govern this new and exciting space. Autonomous vehicles promise to move the world into a new era of almost limitless potential but only if society, industry, and policy are capable of moving with it.
ContributorsGalvin, Sarah Nicole (Author) / Krause, Stephen (Thesis director) / Anwar, Shahriar (Committee member) / School of Politics and Global Studies (Contributor) / Materials Science and Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05
Description
Titanium dioxide is an essential material under research for energy and environmental applications, chiefly through its photocatalytic properties. These properties allow it to be used for water-splitting, detoxification, and photovoltaics, in addition to its conventional uses in pigmentation and sunscreen. Titanium dioxide exists in several polymorphic structures, of which the most common are rutile and anatase. We focused on anatase for the purposes of this research, due to its promising results for hydrolysis.
Anatase exists often in its reduced form (TiO2-x), enabling it to perform redox reactions through the absorption and release of oxygen into/from the crystal lattice. These processes result in structural changes, induced by defects in the material, which can theoretically be observed using advanced characterization methods. In situ electron microscopy is one of such methods, and can provide a window into these structural changes. However, in order to interpret the structural evolution caused by defects in materials, it is often necessary and pertinent to use atomistic simulations to compare the experimental images with models.
In this thesis project, we modeled the defect structures in anatase, around oxygen vacancies and at surfaces, using molecular dynamics, benchmarked with density functional theory. Using a “reactive” forcefield designed for the simulation of interactions between anatase and water that can model and treat bonding through the use of bond orders, different vacancy structures were analyzed and simulated. To compare these theoretical, generated models with experimental data, the “multislice approach” to TEM image simulation was used. We investigated a series of different vacancy configurations and surfaces and generated fingerprints for comparison with TEM experiments. This comparison demonstrated a proof of concept for a technique suggesting the possibility for the identification of oxygen vacancy structures directly from TEM images. This research aims to improve our atomic-level understanding of oxide materials, by providing a methodology for the analysis of vacancy formation from very subtle phenomena in TEM images.
Anatase exists often in its reduced form (TiO2-x), enabling it to perform redox reactions through the absorption and release of oxygen into/from the crystal lattice. These processes result in structural changes, induced by defects in the material, which can theoretically be observed using advanced characterization methods. In situ electron microscopy is one of such methods, and can provide a window into these structural changes. However, in order to interpret the structural evolution caused by defects in materials, it is often necessary and pertinent to use atomistic simulations to compare the experimental images with models.
In this thesis project, we modeled the defect structures in anatase, around oxygen vacancies and at surfaces, using molecular dynamics, benchmarked with density functional theory. Using a “reactive” forcefield designed for the simulation of interactions between anatase and water that can model and treat bonding through the use of bond orders, different vacancy structures were analyzed and simulated. To compare these theoretical, generated models with experimental data, the “multislice approach” to TEM image simulation was used. We investigated a series of different vacancy configurations and surfaces and generated fingerprints for comparison with TEM experiments. This comparison demonstrated a proof of concept for a technique suggesting the possibility for the identification of oxygen vacancy structures directly from TEM images. This research aims to improve our atomic-level understanding of oxide materials, by providing a methodology for the analysis of vacancy formation from very subtle phenomena in TEM images.
ContributorsShindel, Benjamin Noam (Author) / Crozier, Peter (Thesis director) / Anwar, Shahriar (Committee member) / Singh, Arunima (Committee member) / Materials Science and Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05