Abstract: A method for providing frequency agility in a wireless network with a plurality of RF frequency channels. The nodes are formed into a hierarchical branching tree for communication. The RF environment for each of the plurality of RF channels is sensed as a function of time and the sensed measurements are stored. Based on the stored measurements of RF environment, a channel assignment scheme as a function of time is selected and transmitted to the network nodes. Nodes within the tree can be segmented geographically and assigned channels based on the sensed local RF environment. Nodes can also be segmented to reduce the density of nodes using the same assigned channels. Such frequency agility enhances the communication capability of a wireless sensor network in a harsh RF environment.

Abstract: A carrier pocket engineering technique used to provide superlattice structures having relatively high values of the three-dimensional thermoelectric figure of merit (Z3DT) is described. Also described are several superlattice systems provided in acordance with the carrier pocket engineering technique. Superlattice structures designed in accordance with this technique include a plurality of alternating layers of at least two different semiconductor materials. First ones of the layers correspond to barrier layers and second ones of the layers correspond to well layers but barrier layers can also work as well layers for some certain carrier pockets and vice-versa. Each of the well layers are provided having quantum well states formed from carrier pockets at various high symmetry points in the Brillouin zone of the structure to provide the superlattice having a relatively high three-dimensional thermoelectric figure of merit.

Abstract: A superlattice structure for thermoelectric power generation includes m monolayers of a first barrier material alternating with n monolayers of a second quantum well material with a pair of monolayers defining a superlattice period and each of the materials having a relatively smooth interface therebetween. Each of the quantum well layers have a thickness which is less than the thickness of the barrier layer by an amount which causes substantial confinement of conduction carriers to the quantum well layer and the alternating layers provide a superlattice structure having a figure of merit which increases with increasing temperature.

Abstract: A superlattice structure for use in thermoelectric power generation systems includes m layers of a first one of Silicon and Antimony doped Silicon-Germanium alternating with n layers of Silicon-Germanium which provides a superlattice structure having a thermoelectric figure of merit which increases with increasing temperature above the maximum thermoelectric figure of merit achievable for bulk SiGe alloys.