Abstract: The invention relates to micro fuel cell systems whose performance is enhanced by an accurate fluid delivery system. The fluid delivery system improves reactant fluid provision to meet electrical output, while maintaining correct stoichiometries for chemical processing in a downstream reactor. The fluid delivery system includes a pressure source and a differential flow meter. The differential flow meter uses a flow restrictor and a sensor. The pressure source moves a fluid through the flow restrictor; the sensor detects differential pressure in the flow restrictor and outputs a signal that permits dynamic control of fluid flow, e.g., by controlling a pump.

Abstract: A helmet structure including a transparent shell. The transparent shell including a matrix of ventilation apertures coextensive with the shell. The shell further including a visor mounted at a forward end thereof overlying a forward facial opening, including lateral ventilation ports positioned coextensive with the visor laterally displaced side edges. The shell includes a multi-layer construction, including an inner and outer transparent layer sandwiching a central laminate layer of photochromic material to accommodate various environmental lighting conditions. A modification of the invention includes a further inner layer defined by an inflatable transparent polymeric material, including a squeeze bulb to direct air interiorly thereof to accommodate individuals' varying cranial geometric configurations, as well as providing an enhanced safety layer within the helmet structure.