Recent studies have shown that high intensity focused ultrasound (HIFU) accelerates thrombolysis for ischemic stroke. Although the mechanisms are not fully understood, cavitation is thought to play an important role. The goal of this paper is to investigate the potential for cavitation to cause mechanical damage to a blood clot. The amount of damage to the fiber network caused by a single bubble expansion and collapse is estimated by two independent approaches: One based on the stretch of individual fibers and the other based on the energy available to break individual fibers. The two methods yield consistent results. The energy method is extended to the more important scenario of a bubble outside a blood clot that collapses asymmetrically creating an impinging jet. This leads to significantly more damage compared to a bubble embedded within the clot structure. Finally, as an example of how one can apply the theory, a simulation of the propagation of HIFU waves through model calvaria of varying density is explored. The maximum amount of energy available to cause damage to a blood clot increases as the density of the calvaria decreases.

He received a Ph.D. in mechanical engineering from the Massachusetts Institute of Technology [2007] where he held a research assistantship at MIT's Institute for Soldier Nanotechnologies (ISN). At MIT he invented a new nano-enabled garment to provide simultaneous ballistic and thermal protection to infantry soldiers. Dr. Traum also holds a master's degree in mechanical engineering from MIT [2003] with a focus on cryogenics and two bachelor's degrees from the University of California, Irvine [2001]: one in mechanical engineering and the second in aerospace engineering. In addition, he attended the University of Bristol, UK as a non-matriculating visiting scholar where he completed an M.Eng thesis in the Department of Aerospace Engineering [2000] on low-speed rotorcraft control. Prior to his appointment at MSOE, Dr. Traum was a founding faculty member of the Mechanical and Energy Engineering Department at the University of North Texas where he established an externally-funded researcher incubator that trained undergraduates how to perform experimental research and encouraged their matriculation to graduate school. Dr. Traum also serves as the founding Chief Technology Officer at EASENET, a start-up renewable energy company he co-founded with his former students to commercialize residential scale waste-to-energy biomass processor systems.

Tesla turbines produce power at high rotation rate and low torque relative to other prime movers. At a tiny scale, this attribute renders Tesla turbines poorly matched to dynamometers designed to characterize electricand gasoline-powered radio-controlled vehicles and kit cars. Techniques are needed to enable Tesla turbine design and performance evaluation. An analytical modelling approach was recently developed by Carey, and a complimentary experimental technique, dynamic dynamometry, can determine Tesla turbine power curves without a dynamometer. This paper mutually validates these approaches by comparing them to each other using results from a 3D printed 4-disk tiny Tesla turbine with characteristic disk inner/outer diameter of 11.54 ± 0.01 mm and 24.85 ± 0.01 mm respectively. The Carey model predicts maximum power output of 0.077 ± 0.015 W, and dynamic dynamometry predicts 0.122 ± 0.008 W, a 36.9% difference. Bounding assumptions were used and more accurate parameter measurements will drive these values closer together. Peculiarities of tiny Tesla turbine operation are also described, including the discovery that turbine spin-down rotational velocity is not linear with time. This phenomenon is likely caused by fluid boundary layer shear between the housing and outer disks. It is not observed in larger Tesla turbines, suggesting a speed, size and/or disk count threshold at which this phenomenon introduces non-trivial parasitic reduction in performance.

To provide students a more coherent and cohesive view of the mechanical engineering curriculum, we created and are delivering a multicourse curriculum-integrated engineering project that permeates and unifies five required classes within our undergraduate curriculum: 1) Freshman Design, 2) Dynamics, 3) Numerical Analysis, 4) Fluid Mechanics, and 5) Thermodynamics. Students enrolled in these Rocket Project (RP) classes design, build, flight test, and analyze model rockets through hands-on exercises. These activities challenge students to work on different aspects of the same rocket project across all four years of their degree program.Critical to the seamless collection and presentation of data and experimental/numerical techniques across five courses was the development of new laboratory, field, and simulation capabilities driven by our goal: to measure all unknown variables needed for rocket performance analysis and modeling in-house without reliance on external data. These needed capabilities included: 1) collecting acceleration and barometric altitude data from a model rocket flight, 2) simulating via computer rocket trajectories for comparison to actual measured altitudes, 3) evaluating rocket performance by numerical methods to validate modeling assumptions, 4) determining rocket drag coefficient as a function of Reynolds number for velocities relevant to a launch, and 5) measuring rocket motor thrust as a function of time as well as the energy density of the fuel used. As these capabilities were developed, additional course interconnectivities and opportunities for data sharing were discovered and exploited to further enrich the course experience for students.

Rankine cycles will someday be the power plants of choice for manned space missions, providing excellent thermodynamic efficiency and high power density. The Rankine cycle's hallmark is a working fluid that changes phase between liquid and vapor. However, the working fluid must remain in the vapor phase as it passes through the turbine to avoid damaging this component. The need to tightly regulate the working fluid phase through the turbine imposes limits on the power produced and the overall efficiency of the cycle, especially given limitations on power plant volume and mass necessarily imposed by housing it in an interplanetary spacecraft.These limitations could be relaxed if a turbine were incorporated into the Rankine power cycle that was robust and fully operational while processing two-phase flows. Disk turbines have the potential for continuous operation regardless of the thermodynamic quality of working fluid running through them. However, due to high rotational velocity and low torque output by disk turbines, their performance is difficult to evaluate using conventional techniques for aero-derived turbines.To assess disk turbines as candidates for space-based power generation, we describe a method to accurately measure and predict turbine mechanical power output using the rational inertia of the turbine's spinning components and friction in its bearings as the load. The turbine's time response to Dirac load inputs, as well as its no-load responses to compressed air input over a range of pressures, are measured. This technique, called dynamic dynamometry, produces turbine power-versus-angular-velocity curves, useful for quantitative performance analysis.