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This study elaborates the attitude dynamics of a cylinder floating in two immiscible fluids. A cubic polynomial was derived based on the attitude angle, weight, center of gravity, and the density ratio of fluids. The numerical solution was validated by experimental data. Under prescribed constraints for the physical model, we have found that multiple solutions exist for cases with no radially biased center of gravity. When the center of gravity is biased, the attitude angles change abruptly around some critical values, which is related to the density ratio. Moreover, the attitude angles are less sensitive to the varying density ratios when the cylinder is heavier. The results also reveal that the cylinder tends to be vertical for nearly the whole range of density ratios when the center of gravity is slightly biased radially.

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During the formation of Ge fin structures on a silicon-on-insulator (SOI) substrate, we found that the dry etching process must be carefully controlled. Otherwise, it may lead to Ge over-etching or the formation of an undesirable Ge fin profile. If the etching process is not well controlled, the top Ge/SOI structure is etched away, and only the Si fin layer remains. In this case, the device exhibits abnormal characteristics. The etching process is emerging as a critical step in device scaling and packaging and affects attempts to increase the packing density and improve device performance. Therefore, it is suggested that optimization of operating the plasma reactor be performed through simulations, in order to not only adjust the process parameters used but also to modify the hardware employed. We are going to develop Ge junction-less devices by employing updated fabrication parameters. Besides, we want to eliminate misfit dislocations at the interface or to reduce threading dislocations by applying cyclic thermal annealing process to meet the goal of obtaining suspended structure of epitaxial Ge layers with high quality.

Simulated moving bed chromatography process, which is a multicolumn chromatography process, has been used in various industrial applications. Dynamic axial compression columns are key elements in simulated moving beds, and their flow characteristics are worth exploring using state-of-the-art numerical methodologies. In this study, new fluid distributors for the dynamic axial compression column were designed and fabricated based on mass conservation in fluid mechanics and the computer-aided design in the preliminary stage. Computational fluid dynamics was employed to resolve the flow field, and the numerical chromatograms were validated by laboratory experiments. For the computational fluid dynamics–based simulation of flow in the dynamic axial compression, the transient laminar flow fields were described by the momentum and species transport equations with Darcy’s law to model the porous zone in the packed bed. In addition, reverse engineering processes were applied to obtain the unknown physical parameters, such as viscous resistance and adsorption equilibrium coefficients. Moreover, including the adsorption equilibrium equation in the fundamental governing equations made the simulated results agree with the experimental data in chromatograms, providing a more feasible result for practical applications.