Esther A. Hughes

Scheduling for information gathering on sensor network

We investigate a unique wireless sensor network scheduling problem in which all nodes in a cluster send exactly one packet to a designated sink node in an effort to minimize transmission time. However, node transmissions must be sufficiently isolated either in time or in space to avoid collisions. The problem is formulated and solved via graph representation. We prove that an optimal transmission schedule can be obtained efficiently through a pipeline-like schedule when the underlying topology is either line or tree. The minimum time required for a line or tree topology with

Scheduling on sensor hybrid network

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Efficient route establishment and maintenance in wireless sensor networks with mobile base stations

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IEEE-CS/ACM computing curricula: computer engineering & software engineering volumes

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A biomedical sensor system for real-time monitoring of astronauts' physiological parameters during extra-vehicular activities

. We further prove that our scheduling problem is NP-hard for general graphs. We propose a heuristic algorithm for general graphs. Our heuristic tries to schedule as many independent segments as possible to increase the degree of parallel transmissions. This algorithm is compared to an RTS/CTS based distributed algorithm. Preliminary simulated results indicate that our heuristic algorithm outperforms the RTS/CTS based distributed algorithm (up to 30%) and exhibits stable behavior.

An Efficient Multicast Scheme with Orthogonal CTS Encoding in Wireless Network.

Mathematical models and circuitry necessary for optimal energy conversion have been developed for piezoelectric devices because of their ability to convert mechanical energy to electrical energy. The piezoelectric device that is the focus of this study is a curved, thin unimorph prestressed bender. This device consists of layers of piezoelectric material, polyimide, and metal bonded at high temperatures. Effects of its layer composition and geometry on energy harvesting and actuation are investigated. Through this investigation, a method for developing empirical relationships is established and it is demonstrated that an actuator can be engineered so that the same energy output could be obtained with different materials by adjusting relevant parameters.