Mechanical Engineering Commons^™

Optimization And Correlation Of The Penn State Model Of Friction Stir Welding To Experimental Welds In 304l Stainless Steel, Devin Donaldson Furse

Theses and Dissertations

A numerical model of friction stir welding developed by T. DebRoy, R. Nandan, and others has been optimized to fit experimental data of eleven welds of 304L stainless steel at various weld feed rates and spindle speeds. Optimization was used to determine the values of five difficult-to-measure model parameters. The optimal parameter values were then correlated to the weld machine inputs. The mechanical efficiency and the coefficient of friction were not correlated with feed rate, spindle speed, or axial pressure. Tool slip was positively correlated with feed rate, negatively correlated with spindle speed, and not correlated with axial pressure. The …

Mathematical Modeling Of Light Utilization And The Effects Of Temperature Cycles On Productivity In A Steady-State Algal Photobioreactor, Peter Edwin Zemke

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The work presented here investigated two methods of improving productivity in microalgal photobioreactors: applying temperature cycles intended to maximize photosynthesis and minimize respiration, and development of a mathematical model that predicts improvements in photon utilization using temporal light dilution (flashing).

The experiments conducted on diurnal temperature cycles with Dunaliella tertiolecta in 30-L outdoor photobioreactors showed that a properly chosen temperature cycle can improve mass and energy productivity by 18% over an identical photobioreactor with a constant temperature. However, excessively large temperature cycle amplitudes reduced productivity. A 4-7% increase in energy content was observed in microalgae exposed to temperature cycles. The …

Aircraft Gearbox Dynamics Subject To Electromechanical Actuator Regenerative Energy Flow, Matthew S. Rutledge

Browse all Theses and Dissertations

To increase reliability and efficiency, standard aircraft components are being replaced with more electric subsystems aimed to reduce weight, conserve space, and improve energy management. One application of this process replaces standard hydraulic actuators used in flap or aileron movements with electromechanical actuators powered by an external generator. During different types of return movements, the electromechanical actuator will produce regenerative power that flows back through the generator and pulses into the engine-gearbox subsystem. The regenerative power, defined by characteristic amplitude, frequency, and other pulse attributes, coupled with the driving force produced by the engine may dramatically impact the performance and …