Abstract: A wind turbine arrangement is disclosed that includes a substantially vertical tower mounted to a ground surface, a horizontally-extending hub rotatably fixed in a substantially horizontal plane to an upper end of the tower, at least one radial support arm rotatably fixed with a distal end of the hub, each support arm including a turbine mounting means at a distal end thereof, and at least one electricity-generating turbine selectively mountable with the turbine mounting means of the any of the support arms. An elevator means adapted to raise and lower each of the turbines between an upper loading position adjacent to a lower loading position of each support arm, and a lower loading position adjacent to the ground surface. In use, each support arm may be rotated to the loading position for receiving one of the turbines thereon. The support arm is then rotated about the hub into an operating position.

Abstract: A portable oxygen concentrator system adapted to be readily transported by a user includes a rechargeable energy source and a concentrator powered by the energy source. The concentrator converts ambient air into concentrated oxygen gas for the user and includes a plurality of adsorption beds and a rotary valve assembly. The rotary valve assembly is relatively rotatable with respect to the plurality of adsorption beds to provide valving action for selectively transferring fluids through the plurality of adsorption beds for converting ambient air into concentrated oxygen gas for the user. The ratio of adiabatic power to oxygen flow for the concentrator is in the range of 6.2 W/LPM to 23.0 W/LPM.