Yung-Kuei Chiang

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In a wireless sensor network (WSN), a great number of sensor nodes are deployed to gather sensed data. These sensor nodes are typically powered by batteries so their energy is restricted. Sensor nodes mainly consume energy consumption in data transmission, especially for a long distance. Since the location of the base station (BS) is remote, the energy(More)
In wireless sensor networks (WSNs), sink mobility has been drawing more and more attention in recent years. Some approaches suggest that mobile sinks repeatedly propagate packets to notify the potential sources of their latest location information. As a result, frequent location updates from multiple sinks introduce both increased transmission traffic and(More)
In this paper, we propose a dual-path-based data aggregation scheme (DPBDAS) for grid-based wireless sensor networks (WSNs). We build a grid infrastructure by equally partitioning the whole sensor field into a grid of cells. The sensor nodes are randomly classified as type A and type B. All sensor nodes of type A and type B in the grid are further organized(More)
In this paper, we propose a power efficient data dissemination (PEDD) scheme for wireless sensor networks (WSNs) with mobile sinks. A source proactively constructs a grid structure to disseminate data to the mobile sinks. For each grid point, a cost function is applied to choose a dissemination node to serve it. Only the dissemination nodes are in working(More)
In this paper, we propose a Cycle-Based Data Aggregation Scheme (CBDAS) for grid-based wireless sensor networks (WSNs). The whole sensor filed is partitioned into a 2D logical grid of cells. Each cell has a head responsible for aggregating its own data with the data sensed by the others in the same cell and then transmitting out. In order to efficiently and(More)
The research and development of next generation networks results in continuously growing in heterogeneity of wireless systems. Those systems also offer users the increasing possibility of roaming between different networks, which undoubtedly needs seamless integration. As mobile users continue to expand their requirements for seamless roaming, a good(More)
⎯ Electrically pumped high power terahertz (THz) emitters that operated above room temperature in a pulse mode were fabricated from nitrogen-doped n-type 6H-SiC. The emission spectra had peaks centered on 5 THz and 12 THz (20 meV and 50 meV) that were attributed to radiative transitions of excitons bound to nitrogen donor impurities. Due to the relatively(More)
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