Thermal transport in nanowires and nanotubes has attached much attention due to their use in various functional devices and their use as a model system for low dimensional transport phenomena. The precise control of the crystal structure, defects, characteristic size, and electronic properties of nanowires has allowed for fundamental studies of phonon and electron transport in a variety of nanoscale systems. The thermal conductivity in nanostructured materials can vary greatly compared to bulk values owing to classical and quantum size effects. In this work, two model systems for investigating fundamental phonon transport were investigated for potential use in thermoelectric and thermal management applications. The thermoelectric properties of twin defect indium arsenide nanowires and the thermal conductivity of polythiophene nanofibers with improved polymer chain crystallinity were measured with a microfabricated measurement device. The effects of twin planes on reducing the mean free path of phonons in indium arsenide and the effects of improved chain alignment in increasing the thermal conductivity in polymer fibers is discussed. / text

The desired lifetime for CO₂ injection for sequestration is several decades at a high injection rate (up to 10 bbl/min or 2,400 tons/day per injector). Government regulations and geomechanical design constraints may impose a limit on the injection rate such that, for example, the bottomhole pressure remains less than 90% of the hydraulic fracture pressure. Despite injecting below the critical fracture pressure, fractures can nevertheless initiate and propagate due to a thermoelastic stress reduction caused by cool CO₂ encountering hot reservoir rock. Here we develop a numerical model to calculate whether mechanical and thermal equilibrium between the injected CO₂ and the reservoir evolves, such that fracture growth ceases. When such a condition exists, the model predicts the corresponding fracture geometry and time to reach that state. The critical pressure for fracture propagation depends on the thermoelastic stress, a function of rock properties and the temperature difference between the injected fluid and the reservoir (ΔT). Fractures will propagate as long as the thermoelastic stress and the fluid pressure at the fracture tip exceed a threshold; we calculate the extent of a fracture such that the tip pressure falls below the thermoelastically modified fracture propagation pressure. Fracture growth is strongly dependent upon the formation permeability, the level of injection pressure above fracture propagation pressure, and ΔT. / text

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Implementation of a control system for an active camouflage system based on thermal elements and LED technology.

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Sustainable Built Environments Senior Capstone / In today’s society we are faced with many problems that result from the use of traditional energy sources. Due to the lack of efficient alternative energy sources we are consistently trying to produce technologically advanced methods and tools to offset our dependency on traditional energy systems that are harming the planet as a whole. Every great accomplishment needs a starting point. The University of Arizona is going to an influential success story that gets the ball rolling. Implementing two energy saving tools known as photovoltaic panels and thermal water heating units will allow advocates to see the benefits that can come from sustainable technology. Through state and federal incentives solar panels are able to pay themselves off over the years in a majority of the states. Without federal or state incentives, the solar panels would not save the consumer enough money to repay their initial investment. Thermal water heating units save the consumer enough money to pay themselves off over the years. Overall both thermal water heating units and photovoltaic panels provide a clean source of energy.

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