There are many DOA estimation methods based on different signal features, and these methods are often evaluated by experimental results, but lack the necessary theoretical basis. Therefore, a direction of arrival (DOA...There are many DOA estimation methods based on different signal features, and these methods are often evaluated by experimental results, but lack the necessary theoretical basis. Therefore, a direction of arrival (DOA) estimation system based on self-organizing map (SOM) and designed for arbitrarily distributed sensor array is proposed. The essential principle of this method is that the map from distance difference of arrival (DDOA) to DOA is Lipschitz continuity, it indicates the similar topology between them, and thus Kohonen SOM is a suitable network to classify DOA through DDOA. The simulation results show that the DOA estimation errors are less than 1° for most signals between 0° to 180°. Compared to MUSIC, Root-MUSIC, ESPRIT, and RBF, the errors of signals under signal-to-noise ratios (SNR) declines from 20 dB to 2 dB are robust, SOM is better than RBF and almost close to MUSIC. Further, the network can be trained in advance, which makes it possible to be implemented in real-time.展开更多
Microwave ablation therapy has become an important method for tumor treatment in recent years.The temperature and the coagulation region need real-time noninvasive monitoring to ensure the safety and effectiveness dur...Microwave ablation therapy has become an important method for tumor treatment in recent years.The temperature and the coagulation region need real-time noninvasive monitoring to ensure the safety and effectiveness during the treatment.The authors reviewed the ultrasonic monitoring methods for tumor microwave ablation therapy both at home and abroad.In addition,the authors also prospected this technique in the future.展开更多
文摘There are many DOA estimation methods based on different signal features, and these methods are often evaluated by experimental results, but lack the necessary theoretical basis. Therefore, a direction of arrival (DOA) estimation system based on self-organizing map (SOM) and designed for arbitrarily distributed sensor array is proposed. The essential principle of this method is that the map from distance difference of arrival (DDOA) to DOA is Lipschitz continuity, it indicates the similar topology between them, and thus Kohonen SOM is a suitable network to classify DOA through DDOA. The simulation results show that the DOA estimation errors are less than 1° for most signals between 0° to 180°. Compared to MUSIC, Root-MUSIC, ESPRIT, and RBF, the errors of signals under signal-to-noise ratios (SNR) declines from 20 dB to 2 dB are robust, SOM is better than RBF and almost close to MUSIC. Further, the network can be trained in advance, which makes it possible to be implemented in real-time.
基金supported by the National Natural Science Foundation of China(Grant No.30770547).
文摘Microwave ablation therapy has become an important method for tumor treatment in recent years.The temperature and the coagulation region need real-time noninvasive monitoring to ensure the safety and effectiveness during the treatment.The authors reviewed the ultrasonic monitoring methods for tumor microwave ablation therapy both at home and abroad.In addition,the authors also prospected this technique in the future.
