Successful application of inductive energy storage depends critically on the performance of the opening switch. The new Hawk generator at NRL1 is used in plasma opening switch (POS) experiments in the 1-~s conduction time regime to study lon9 conduction time POS physics. In th1s experiment, different POS configurations were used, including various switch to load distances and different cathode ...

This work starts from the analysis of the literature about the Random Access protocols with contention resolution, such as Contention Resolution Diversity Slotted Aloha (CRDSA), and introduces a possible enhancement, named Generalized Encoding Contention Resolution Diversity Slotted Aloha (GE-CRDSA). The GE-CRDSA aims at improving the aggregated throughput when the system load is less than 50%,...

eGaN FETs have repeatedly demonstrated higher efficiency than MOSFETs in wireless power transfer amplifiers when operated over a wide impedance range using a ZVS Class D amplifier [1, 2, 3, 4, 5, 6, 7, and 8]. In this article we examine a method to further improve the performance of eGaN FETs by replacing the bootstrap diode of the high side gate driver with an eGaN FET that is driven synchrono...

PEM fuel cells in a Ballard Nexa stack were analyzed via AC impedance using a Gamry FC350 monitor and a TDI electronic load. Single MEAs, multiple MEA cell groups, and full 47 MEA stacks were examined. Impedance results were successfully fit to equivalent circuit diagrams containing charge transfer polarization resistances related to activation energies, uncompensated resistances related to the...

microgrids are nowadays used to produce electric energy with more efficiency and advantage. however, the use of microgrids presents some challenges. one of the main problems of the microgrids widely used in electrical power systems is the control of voltage, frequency and load sharing balance among inverter- based distributed generators (dgs) in islanded mode. droop method performance degrades ...

t-shape profile barriers are one of the most successful barriers among many different profiles. it has been shown that using welled diffusers on the top of t-shaped barriers makes a reactive barrier that shows better performance than that of any other used profile barriers compared with their equivalent absorbent barrier. the contribution of the top surface of reactive t-profile barriers to the...

In this paper a variety of techniques to characterize the mechanical properties of polymers in the MHz frequency range based on the impedance analysis of thickness and thickness shear composite resonators will be presented. The analysis is based on inverting the impedance data of the composite resonator to find the best fit using the material coefficients of the piezoelectric resonator and atta...

A laboratory experiment for the introductory electrical circuit course is presented. The experiment consists of the measurement of real commercial capacitors’ impedance using a relatively low-cost impedance meter, and further analysis on two levels. First, when results follow well the conventional impedance expression of an ideal capacitor, the capacitance can be determined accurately. Second, ...

Four-terminal impedance meters based on pseudo-bridges yield unexpected uncertainties when using high-contact-impedance electrodes. Adding a front-end amplifier to the impedance meter and rearranging the connection of the meter terminals overcome the contact impedance problem. However, because the compensation provisions in the instrument are meant to compensate only impedance residuals of test...

Integrative approaches to studying the coupled dynamics of skeletal muscles with their loads while under neural control have focused largely on questions pertaining to the postural and dynamical stability of animals and humans. Prior studies have focused on how the central nervous system actively modulates muscle mechanical impedance to generate and stabilize motion and posture. However, the qu...