Abstract. The design of matching circuit for broadband underwater acoustic transducer is a key technology in sonar system. Matching circuit can reduce the energy loss of the power amplifier, extend the system bandwidth and improve the distortion of the transmitted waveform. In this paper, the theory of real frequency direct computational technique (RFDT) is discussed. Then, we design the matching circuit for a tubular transducer. Finally, the match performance is tested in anechoic pool. The results illustrate that the broadband matching circuit can expand the bandwidth and improve the efficiency of the transmitter. Compared with the transmitter without matching, the sound source level of the system increased about 10dB. Compared with the single inductor matching circuit, the work bandwidth is extended. The whole design process of broadband matching circuit completed with computer and without the equivalent circuit of the transducer, so the RFDT is fit for practical project.
With chaotic dynamics analysis to the mechanical vibration signals of on-load tap changers(OLTC) operations, a geometric feature extraction scheme is developed for phase portrait structure based on a multi-dimensional coordinate space. The fuzzy set theory is further introduced into OLTC mechanical fault diagnosis, with a view to establishing the normal distribution membership function of every condition fuzzy set. Regarding two sample categories, i.e. single analyte sample and analyte sample sets, both principles of the largest membership and the optional nearly are used for fuzzy reasoning to finally realize mechanical fault diagnosis of OLTC.
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