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Xie Y.,CAS Shenyang Institute of Metal Research | Yang Y.,CAS Shenyang Institute of Metal Research | Wang M.,CAS Shenyang Institute of Metal Research | Hou J.,Shenyang Liaohai Equipment Co.
Acta Metallurgica Sinica (English Letters)

MCrAlY/TaC metal matrix composite coatings with 10, 20 and 30 wt.% TaC have been successfully produced by electrospark deposition (ESD). The effects of TaC content on microstructure, hardness and oxidation behavior of the composite coatings were studied. The results showed that the composite coatings were composed of superfine columnar dendrite and large TaC particles dispersedly distributed. The hardness was enhanced but oxidation resistance of the composite coatings was reduced with increasing TaC contents. © The Chinese Society for Metals and Springer-Verlag Berlin Heidelberg. Source

Zhu G.,Harbin Engineering University | Wang F.,Harbin Engineering University | Wang F.,Shenyang Liaohai Equipment Co. | Sun H.,Harbin Engineering University
Harbin Gongcheng Daxue Xuebao/Journal of Harbin Engineering University

When active sonar detects a bottom target, because of the disturbance from serious bottom reverberation, the copy-correlation method cannot effectively extract the highlight feature of the bottom target, which reduces the performance of target recognition. In this paper, the method for extracting the highlight feature of bottom target based on time-frequency domain filtering and Hough transforming is researched. In this method, firstly the received signal and copy of transmitted signal were transformed into time-frequency domain by means of cross Wigner-Ville transform. Next, the reverberation and noise were filtered by Ridgelet transform filter according to the different characters of energy distribution in time-frequency domain between the target echo and reverberation. Finally, the peaks of highlight were obtained using Hough transform and the feature vectors were extracted by projecting it into ρ axis. The mathematical relation between the target highlight and the position of peak value in Hough transform domain was researched at the same time. The steps for extracting the bottom target highlight features based on time-frequency domain were given. The performance of recognition was compared between the new method and copy-correlation method using support vectors machine in simulation and real experiments. The results showed that the new method can reduce the reverberation and noise in time-frequency domain and thereby improve recognition performance with a low signal reverberation ratio. ©, 2015, Editorial Board of Journal of HEU. All right reserved. Source

Liu X.-Z.,Northeastern University China | Shao X.,Northeastern University China | Shao X.,Shenyang Liaohai Equipment Co. | Yang Y.-H.,Northeastern University China | Chen X.-B.,Northeastern University China
Dongbei Daxue Xuebao/Journal of Northeastern University

A new blind multi-user detection algorithm was proposed on the basis of complex FastICA in MIMO-OFDM system. With the proposed algorithm, the separation of multi-user could be speeded up by fast convergence characteristics of complex FastICA algorithm firstly, and the indeterminacy of amplitude and indeterminacy of phase by CFastICA algorithm were revised by using correlation function. At last, comparing the improved algorithm with the complex natural gradient learning algorithm (CNGLA), it was proved that CFastICA algorithm has not only faster convergent speed but also smaller bit error rate. It also indicated that using more numbers of receiving antennas would get better signal separation. Source

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