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Full-Text Articles in Biomedical Engineering and Bioengineering

Electron Microscopic Observations Of Interfacial Voids In Aluminum Created By Alkaline Dissolution, Saikat Adhikari, L. Scott Chumbley, H. Chen, Y. C. Jean, A. C. Geiculescu, Kurt R. Hebert Jan 2007

Electron Microscopic Observations Of Interfacial Voids In Aluminum Created By Alkaline Dissolution, Saikat Adhikari, L. Scott Chumbley, H. Chen, Y. C. Jean, A. C. Geiculescu, Kurt R. Hebert

Chemical and Biological Engineering Conference Presentations and Proceedings

We report evidence from electron microscopy and positron annihilation spectroscopy (PAS) for the formation by alkaline dissolution of nm-scale voids in aluminum near the metal-oxide interface. Imaging was carried out using transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM) and field emission scanning electron microscopy (FESEM). EM images supported the PAS finding that voids were found within tens of nm of the interface, and revealed that the void number density increased by at least 10 times due to dissolution. From TEM, void number densities were on the order of 108 cm-2. From TEM and SEM, voids appeared circular in ...


Model For The Steady-State Growth Of Porous Anodic Alumina Films, Jerrod E. Houser, Kurt R. Hebert Jan 2006

Model For The Steady-State Growth Of Porous Anodic Alumina Films, Jerrod E. Houser, Kurt R. Hebert

Chemical and Biological Engineering Conference Presentations and Proceedings

Simulations were developed for the distributions of electrical potential and incorporated anions in porous anodic alumina (PAA) films during steady-state growth. Predictions of a model for the potential distribution based on Laplace's equation were compared to those of the current continuity equation in conjunction with high-field conduction. It was found that Laplace's equation, which has been used previously in PAA models, resulted in strong violations of charge conservation, when the current density was evaluated using the high field conduction equation. Interface motion predicted by the current continuity equation was nearly uniform except near convex ridges on the metal-film ...


Continuous-Time Block-Oriented Adaptive On-Line Modeling For Time Varying Systems, Derrick K. Rollins Sr., Stephanie Loveland Jan 2005

Continuous-Time Block-Oriented Adaptive On-Line Modeling For Time Varying Systems, Derrick K. Rollins Sr., Stephanie Loveland

Chemical and Biological Engineering Conference Presentations and Proceedings

The development and maintenance of accurate predictive models for dynamic systems are highly challenged by system complexity, limited information (i.e., data), changing cross and time correlation structures and changing model parameters. Thus, for a model or modeling method to achieve long term success in implementation into a real system, it must be phenomenologically sound and adaptive, as well as being capable of immediate update from recently obtained process data (i.e., plant data). A model is phenomenologically sound when its structure accurately captures physical input and output relationships, and the stochastic behavior of process and measurement noise. On-line adaptive ...