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Abstract This study is to examine the phenomena caused by rolling action of a nano-particle against the work surface. The analysis was done by the molecular dynamics method. The distributed computing scheme was adopted in these simulations to increase the computing efficiency. The study includes the interfacial force between the nano-particle, the work and the roughness of the work surface, and the damage layer thickness of the work surface. It is done by first identifying the main factors, and then to understand how the phenomena is affected by these factors. Finally, the results of these simulations were discussed. The results show that the interactive force most comes from the breaking process between the work surface and the nano-particle. When the nano-particle¡¦s rolling speed is increased, the interactive force is enhanced. But if the speed has reached a high value, the interactive force will be saturated. The interactive force is not significantly affected by temperature. When the adhesive strength between the nano-particle and the work is higher, the interactive force is higher. The roughness of the work surface is affected by the rolling speed of the nano-particle, the temperature, and the adhesive strength between the nano-particle and the work. If the temperature or the interactive force is higher, the roughness of the work surface is higher. If the rolling speed is higher, the roughness of the work surface will increase. But if the rolling speed has reached a high value, the roughness of the work surface will not increase. The damage layer thickness of the work surface is little affected by the rolling speed of the nano-particle or temperature or the adhesive strength between the nano-particle and the work surface.

Thesis (Ph. D.)--University of Texas at Austin, 2000. / Vita. Includes bibliographical references (leaves 94-99). Available also in a digital version from Dissertation Abstracts.

Thesis (Ph. D.)--University of Washington, 2002. / Vita. Includes bibliographical references (leaves 118-126).

Thesis (Ph.D)--Chemical Engineering, Georgia Institute of Technology, 2009. / Committee Chair: Ludovice, Pete; Committee Member: Chen, Rachel; Committee Member: Harvey, Steve; Committee Member: Sambanis, Athanassios; Committee Member: Wartell, Roger. Part of the SMARTech Electronic Thesis and Dissertation Collection.

Graphene is a single layer two-dimensional honeycomb lattice of carbon atoms. It is one of the toughest, lightest, and most conductive materials known. Graphene was first isolated using adhesive tape in 2004, and awarded the Physics Nobel Prize in 2010. Here we focus on the mechanical properties of graphene. First we present an analytical study, together with numerical simulations, of ripples in graphene. We show that ripples observed in free-standing graphene sheets can be a consequence of adsorbed OH molecules sitting on random sites. The adsorbates cause the bonds between carbon atoms to lengthen slightly. In the second part of this work we study the fracture mechanics of graphene. Experiments on free-standing graphene can expose the graphene sheets to out-of-plane forces. Here we show that out-of-plane forces can cause free-standing graphene to fracture. This fracture mode is known as the tearing mode and is common in materials such as paper. We present a numerical study of the propagation of cracks in clamped, free-standing graphene as a function of the out-of-plane force. We also obtain an analytical expression for the minimum force required to tear a two dimensional sheet, which is our model of graphene, in terms of the initial crack length. / text

No description available.

published_or_final_version / abstract / toc / Chemistry / Doctoral / Doctor of Philosophy

Hydrothermal fluids near and above the critical point of water have unique and potentially very useful thermophysical properties. At present, the lack of knowledge of supercritical water chemistry hinders implementation of innovative hydrothermal technologies. The development of new experimental methods and application of molecular modeling tools is clearly warranted to provide a better understanding of the complex properties of aqueous systems at elevated temperatures and pressures. The thermodynamic, dielectric and transport properties of hydrothermal fluids are investigated using Molecular Dynamics (MD) simulation and flow injection techniques. The spatial hydration structures and self-diffusion coefficients of phenol, aniline and naphthalene in aqueous infinitely dilute solution are examined from ambient to supercritical conditions by means of MD simulations. It is shown that the solvation shell around aromatic molecules undergoes significant changes along the liquid-vapour coexistence curve and, essentially, disappears at supercritical conditions. The changes in hydration structures are reflected in the values of the self-diffusion coefficients which dramatically increase near the critical point of water. The thermodynamic and dielectric properties of the Simple Point Charge Extended (SPC/E) water model are examined over a broad range of sub- and supercritical states. Accurate thermodynamic and dielectric equations of state (EOS) for the SPC/E water model are presented. The parameterizations provide the most accurate, up-to-date description of the properties of high-temperature SPC/E water, thus enabling for the direct comparison of molecular simulation results with experimental data via the corresponding states principle. The experimental methodology for the study of aqueous fluids at extreme conditions by using the ex situ flow injection technique is presented. The methodology significantly simplifies the technical aspects of flow injection analysis in hydrothermal fluids as sample injection and detection are performed at ambient temperature, thus allowing the use of standard on-line detection methods. The proposed ex situ experimental technique is applied to the examination of the hydrodynamic regime of a flow-through tubular reactor from ambient to supercritical water conditions. Application of the ex situ Taylor dispersion technique to measurements of the binary diffusion coefficients in hot compressed water is also presented. The ex situ flow injection methodology provides a basis for further development of flow injection analysis techniques at supercritical water conditions. / Thesis (Ph.D, Chemistry) -- Queen's University, 2009-03-05 17:39:30.197

No description available.