Hierarchical VOOH hollow spheres with low crystallinity composed of nanoparticles were prepared by a facile and template-free method, which involved a precipitation of precursor microspheres in aqueous solution at room temperature and subsequent hydrothermal reaction. Quasi-solid-state symmetric and asymmetric supercapacitor (SSC and ASC) devices were fabricated using hierarchical VOOH hollow s...

Photovoltaic arc faults have led to a number of rooftop fires that have caused significant property damage and threatened the safety of building occupants. In response, Article 690.11 was added to the United States 2011 National Electrical Code, requiring new PV systems on or penetrating a building to include a listed arc fault protection device. Many proposed arc fault detectors utilize freque...

An impedance-source (or impedance-fed) power converter (abbreviated as Z-source) and its control method for implementing dc-to-ac, ac-to-dc, ac-to-ac, and dc-to-dc power conversion are presented in this paper. This impedance converter employs a unique impedance network (or circuit) to couple the converter main circuit to the power source, hence provides a unique feature that cannot be obtained ...

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...

In the present work, we report synthesis of surface modified activated carbon (AC). The have been by using silver nanoparticles. process is simple, cost effective and environment friendly. modified-AC powders characterized X-ray diffraction, scanning electron microscopy area pore size measurements. electrochemical performance prepared materials tested fabricating symmetric configuration EDLC ma...