When Shape memory alloy (SMA) wires are embedded in the composite structure with a specific volume fraction, the properties of the resulting hybrid composite structure, which is called SMA-reinforced composite structure, will be reinforced. Some of SMA wires embedded in the composite can be viewed as two electrodes of the capacitor. The deformation of the composite structure will cause change of the capacitor, therefore the segmental SMA wires embedded in the composite may be considered as the self-sensitive element of structure strain monitoring. The measurement circuit monitoring the change of micro capacitor in structure is designed, and it is integrated with radio frequency identification (RFID) technology to compose RFID sensor-tag, and the variation of capacitor is send to the RFID reader wirelessly to form a wireless health monitoring system. Experimental results show that this RFID sensor-tag and its system can be feasibly used in wireless structural health monitoring of SMA-reinforced composite structure.
In view of the current status and shortcomings of existing meter reading systems, in this paper, we proposed an automatic gas meter reading system based on the advantages of gas meter directly reading technology, WSN technology and GPRS technology, introduced the whole scheme and the design of hardware and software in detail. The system is consist of three level network. The first level network and the second level network use the different frequency during communication. It decreases the interface of each other during the translation of the data, and increase the lifetime of the smart gas meter. The system has the advantages of easy construct, flexible layout, lower power consumption
In the traditional ultrasonic flaw detection, two forms of A scan and B scan are mainly used to check the echo information. The traditional method of defect analysis can only detect the existence of defects, but can not locate the exact position and shape of defects. In this paper, we will present a method of locating the defects in ultrasonic detection for rail. In this method, the position information and incidence angle of ultrasonic probe are obtained, and then the propagation path of primary wave and secondary wave of ultrasonic wave in rail is calculated by mathematical modeling. Finally, the internal defects of rail can be located by combining the echo information collected by ultrasonic probe.
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