We used in situ spectroscopic ellipsometry to measure the photocatalytic activity of titania films on fused silica and glass substrates. Amorphous and anatase TiO2 films with a variety of microstructures were prepared by reactive sputtering and pyrolytic deposition. The titania films were coated with thin, spin-cast films of stearic acid [CH3(CH2)16COOH] to represent an organic contaminant. Photooxidation rates were determined from ellipsometric measurements of the reduction in stearic acid film thickness during exposure to UV irradiation at 313 or 365 nm. The photooxidation rate was found to be proportional to I α, where I is the irradiance. The exponent α correlated with the TiO2 crystallinity, having values of approximately 0.7 and 0.8 for amorphous and anatase films, respectively. The largest photooxidation rate was observed for the pyrolytically deposited anatase sample on which X-ray reflectometry and spectroscopic ellipsometry measurements detected the presence of a low-density TiO2 surface layer. To assess the performance of these films in practical applications, the specimens were exposed to wavelength and irradiance conditions that simulated a solar UV spectrum. The most photocatalytically active sample had a stearic acid film removal rate of 22 nm/h, which would be suitable for self-cleaning window applications.

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This paper presents a systematic model for the simulation and analysis of a power-shift transmission that features a dual-clutch design. The paper models the kinematics, dynamics, and control of the transmission for the analysis of powertrain overall performance and shift transient characteristics. The model is implemented in an object-oriented software tool. Analytical formulations and look-up tables are both used for modeling of powertrain components. The vehicle system model is established by integrating the various components and subsystem models according to the transmission power flow and control logic. The input to the simulation model is the vehicle speed-time profile and the output provides the speed follow-up, engine, and clutch operation status for the drive range and shift processes involved. As a numerical example, the model is used for a vehicle equipped with the power-shift transmission to simulate the speed follow-up over a specified drive range and the dynamic transients during shifts.© 2004 American Institute of Physics.

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This paper presents a systematic model for the design and analysis of toroidal traction drive continuously variable transmissions (CVT). The contacts between the input disk, the roller and the output disk of the traction drive are formulated using the classical Hertzian contact theory. The traction force and side slip force occurring in CVT operation are modelled based on the elasto-hydrodynammic theory and are correlated to the traction drive geometric and kinematic parameters. The model allows for the quantitative analysis of traction drive operation under various torque inputs and over the desired ratio range. [S1050-0472(00)01004-7]