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Existing systems for traffic information acquisition have high costs and low scalability owing to their characteristics such as large size, wired power supplies, and wired communication. To achieve low costs and high scalability, the use of traffic information acquisition systems based on wireless sensor networks (WSNs) has been suggested. However, WSN-based systems have important issues, such as low computing power, limited battery capacity, and high transmission delay. Existing studies on WSN-based acquisition systems have not considered all three of these problems together. Moreover, most studies have focused on theoretical problems rather than practical ones. Therefore, we propose a new system that considers all three limitations of WSN-based systems.In our experiments, we installed our system on real roads for an accurate evaluation. The results show that our system has a high detection accuracy, low power consumption, and low transmission delay.

NOMENCLATURE D = chamber diameter H = chamber height d 1 = diffuser inlet width d 2 = diffuser outlet width d 3 = air inlet channel width d 4 = air inlet gate length d 5 = air outlet channel width dh = diffuser lengthIn this paper, we propose a synthetic jet-type micropump for supplying air. Synthetic jet actuators usually include a small single pumping cavity, inlet/outlet channels, and a Lead zirconate titanate(PZT) membrane that exerts the pumping pressure. To determine the optimum design parameters of the air pump, a numerical analysis was carried out by varying its geometry. The optimized air pump was fabricated by replicating PDMS parts from silicon masters patterned by the deep RIE process. The size of the fabricated micropump was 16 × 13 × 3 mm 3 . In order to control the frequency of the PZT membrane and reduce the controller size and power consumption, an SP4423 microchip was used. At a pumping frequency of 80 Hz, a flow rate of 9.5 cc/min, pumping pressure of 438 Pa, and power consumption less than 0.15 mW were achieved.

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