A new fiber optic hydrophone is described. based on a distributed feedback fiber laser (DFB-fiber laser) Experimental arrangement consists of DFB-FL, unbalanced Mach-Zehnder interferometer, piezoelectric (PZT) modulat...A new fiber optic hydrophone is described. based on a distributed feedback fiber laser (DFB-fiber laser) Experimental arrangement consists of DFB-FL, unbalanced Mach-Zehnder interferometer, piezoelectric (PZT) modulator, detection and feedback control circuit, and oscillograph. Experimental results show that the bare DFB-FL hydrophone is extremely sensitive to small perturbations in their environment and can acquire exact acoustic signals.展开更多
Autonomous underwater vehicles(AUV) work in a complex marine environment. Its system reliability and autonomous fault diagnosis are particularly important and can provide the basis for underwater vehicles to take corr...Autonomous underwater vehicles(AUV) work in a complex marine environment. Its system reliability and autonomous fault diagnosis are particularly important and can provide the basis for underwater vehicles to take corresponding security policy in a failure. Aiming at the characteristics of the underwater vehicle which has uncertain system and modeling difficulty, an improved Elman neural network is introduced which is applied to the underwater vehicle motion modeling. Through designing self-feedback connection with fixed gain in the unit connection as well as increasing the feedback of the output layer node, improved Elman network has faster convergence speed and generalization ability. This method for high-order nonlinear system has stronger identification ability. Firstly, the residual is calculated by comparing the output of the underwater vehicle model(estimation in the motion state) with the actual measured values. Secondly, characteristics of the residual are analyzed on the basis of fault judging criteria. Finally, actuator fault diagnosis of the autonomous underwater vehicle is carried out. The results of the simulation experiment show that the method is effective.展开更多
基金Supported by China Scholarship Council, Natural Science Foun-dation of China (grant no.NSFC 60677027)Natural Science Foun-dation of Shandong Province of China (grant no.Y2006G08)Foundation for Doctoral Research of Shandong Academy of Sci-ence (grant no.2005-79).
文摘A new fiber optic hydrophone is described. based on a distributed feedback fiber laser (DFB-fiber laser) Experimental arrangement consists of DFB-FL, unbalanced Mach-Zehnder interferometer, piezoelectric (PZT) modulator, detection and feedback control circuit, and oscillograph. Experimental results show that the bare DFB-FL hydrophone is extremely sensitive to small perturbations in their environment and can acquire exact acoustic signals.
基金Project(2012T50331)supported by China Postdoctoral Science FoundationProject(2008AA092301-2)supported by the High-Tech Research and Development Program of China
文摘Autonomous underwater vehicles(AUV) work in a complex marine environment. Its system reliability and autonomous fault diagnosis are particularly important and can provide the basis for underwater vehicles to take corresponding security policy in a failure. Aiming at the characteristics of the underwater vehicle which has uncertain system and modeling difficulty, an improved Elman neural network is introduced which is applied to the underwater vehicle motion modeling. Through designing self-feedback connection with fixed gain in the unit connection as well as increasing the feedback of the output layer node, improved Elman network has faster convergence speed and generalization ability. This method for high-order nonlinear system has stronger identification ability. Firstly, the residual is calculated by comparing the output of the underwater vehicle model(estimation in the motion state) with the actual measured values. Secondly, characteristics of the residual are analyzed on the basis of fault judging criteria. Finally, actuator fault diagnosis of the autonomous underwater vehicle is carried out. The results of the simulation experiment show that the method is effective.
