Abstract: Techniques for performing channel estimation in an orthogonal time, frequency and space (OTFS) communication system include receiving a wireless signal comprising a data signal portion and a pilot signal portion in which the pilot signal portion includes multiple pilot signals multiplexed together in the OTFS domain, performing two-dimensional channel estimation in a time-frequency domain based on a minimum mean square error (MMSE) optimization criterion, and recovering information bits using a channel estimate obtained from the two-dimensional channel estimation.

Abstract: A recycled energy absorptive/moisture resistive underlayment includes a recycled energy absorbing layer comprised of either a nonwoven fiber batt formed from shoddy fibers or a foam pad formed from bonded foam. To protect the recycled energy absorbing layer from moisture, a moisture barrier is laminated on either one or preferably both side surfaces of the recycled energy absorbing layer. The moisture barrier laminated on a lower side surface of the recycled energy absorbing layer has a projecting flap which projects from first and second edge surfaces of the recycled energy absorbing layer to which the moisture barrier is laminated to the lower side surface thereof. The projecting flap enhances protection of the recycled energy absorbing layer from moisture by preventing moisture from migrating through seams and/or other exposed portions of the recycled energy absorbing layer.

Abstract: In a closed Stirling Cycle system gas, such as dried air, is heated and expanded within a power piston chamber, driving the power piston outwardly of the chamber into contact with a cam groove of a flywheel, rotating the flywheel. When the power piston reaches the top of its stroke, the cam slope reverses, and drives the power piston back into its chamber expelling the heated gas therefrom into one or more cooling chambers, cooling and contracting the gas which is then charged into a recovery piston chamber, driving the recovery piston outwardly of its chamber into contact with another cam groove of the flywheel. When the recovery piston reaches the top of its stroke, its cam groove reverses and drives the recovery piston back into its chamber, expelling the cooled gas therefrom back to the power piston chamber recommencing the power cycle to drive the flywheel. Preferably, several pair of power-recovery pistons operate out of phase to drive the flywheel.