Thermoelectric magnetohydrodynamic control of melt pool dynamics and microstructure evolution in additive manufacturing.

Large thermal gradients in the melt pool from rapid heating followed by rapid cooling in metal additive manufacturing generate large thermoelectric currents. Applying an external magnetic field to the process introduces fluid flow through thermoelectric magnetohydrodynamics. Convective transport of heat and mass can then modify the melt pool dynamics and alter microstructural evolution.

A Parallel Cellular Automata Lattice Boltzmann Method for Convection-Driven Solidification.

This article presents a novel coupling of numerical techniques that enable three-dimensional convection-driven microstructure simulations to be conducted on practical time scales appropriate for small-size components or experiments. On the microstructure side, the cellular automata method is efficient for relatively large-scale simulations, while the lattice Boltzmann method provides one of the fastest transient computational fluid dynamics solvers. Both of these methods have been parallelized and coupled in a single code, allowing resolution of large-scale convection-driven solidification problems.

Thermal dependence of large-scale freckle defect formation.

The fundamental mechanisms governing macroscopic freckle defect formation during directional solidification are studied experimentally in a Hele-Shaw cell for a low-melting point Ga-25 wt.% In alloy and modelled numerically in three dimensions using a microscopic parallelized Cellular Automata Lattice Boltzmann Method. The size and distribution of freckles (long solute channels, or chimneys) are shown to be strongly dependent on the thermal profile of the casting, with flat, concave and convex isotherms being considered.

An evaluation of incentive spirometry in the management of pulmonary complications after cardiac surgery in a pediatric population.

Changes in pulmonary function and the development of atelectasis in the postoperative period have been well documented in the adult population. The use of incentive spirometry has been shown to be effective in the prevention of these postoperative complications. At the Hospital of Sick Children, we studied 17 children (8 control and 9 study) to determine if the same trends occurred.

Oral and inhaled salbutamol in the prevention of exercise-induced bronchospasm.

Oral salbutamol in a dose 0.15 mg/kg of body weight was compared to a total dose of 0.2 mg of salbutamol aerosol in its ability to produce bronchodilation and to prevent exercise-induced bronchospasm (EIB) in 16 asthmatic children in a single-blind crossover study.