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In order to examine the feasibility of full wide-bandgap GaN-based converters in aerospace power conversion applications, this paper proposes a monolithic DC-DC buck converter design with integrated high-side gate driver, over-current protection, and pulse-width-modulation feedback control circuits based on full AlGaN/GaN MIS-HEMT configuration. After model calibration of the DC and transient behaviors with fabricated normally-ON and normally-OFF AlGaN/GaN MIS-HEMT devices, the DC-DC buck converter is simulated. The circuit converts the input 100 V down to an adjustable range at 1 MHz switching frequency. The over-current protection function can properly protect the converter at a preset over-current threshold. The converter can respond to the load current and line input voltage fluctuations due to the integrated feedback control. These results illustrate the performance of proposed all-GaN DC-DC power converter design. [ABSTRACT FROM AUTHOR]

An analytical methodology involving the concept of "electrostatic equilibrium" is developed for granular flow in pneumatic conveying systems. The methodology can be used for estimation of the electrostatic field distribution at various sections of the system and explanation of the mechanisms involved for various electrostatic phenomena observed. For all cases conducted in the conveying system, there was a "charging time" required for the system to reach the state of "electrostatic equilibrium" Experiments conducted at different sections of the system showed that the time required increased in the order." horizontal pipe, vertical pipe, and pipe bend Through a physical analysis, it is deduced that electrostatic equilibrium is related to the granules' behavior and local flow characteristics. In general, a longer time duration taken to reach equilibrium corresponds to a process with mare complicated granular flow patterns. In the electrostatic equilibrium state, the field distribution shows the highest electrostatic field strength near the pipe wall, and this field strength degrades from the pipe wall to the pipe center. At various pipe sections, the highest strength occurs at the bend, in accord with observations that electric sparking first occurs at that location within the entire pneumatic conveying system In the vertical pipe, granular distribution was measured using electrical capacitance tomagraphy (ECT), and granular velocities were cross-referenced with those using particle image velocimetry (PIV). The electrostatic force at low airflow rates is found to be the primary cause for granules sticking to the pipe wall and results in the formation of the half-ring or ring structure. The state of electrostatic equilibrium is physically influenced by several elements in conveying systems. In a cyclic conveying system, a new pipe (or low humidity or no antistatic agent) tends to expedite the process to reach electrostatic equilibrium and attain high magnitude of electrostatic current at the state. In a non-cyclic horizontal conveying system, a thin film (pipe) is found to prolong the process duration to reach equilibrium, while the case with charged film (pipe) takes shorter duration to do so. [ABSTRACT FROM AUTHOR]