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| 1 | A new method for detecting line spectrum of ship-radiated noise using Duffing oscillator显示文摘A detection scheme for line spectrum of ship-radiated noise is proposed using Duffing oscillator. The chaotic trajectory of Duffing oscillator is analyzed and the state equation of the system is improved to detect weak periodic signals in different frequencies. According to the simulation results, the phase transforms of Duffing oscillator are sensitive to periodic signals and immune to the random noise and the periodic interference signals which have larger angular frequency difference from the referential signal. By employing Lyapunov exponents in the field of detection as the criteria for chaos, the phase transforms of dynamic behaviors in quantity are successfully determined. Meanwhile, the threshold value in critical state has been evaluated more accurately. Based on the phase transforms of Duffing oscillator, a new method for detecting line spectrum of ship-radiated noise is given. Three types of ship-radiated noise signals are analyzed and the values of line spectrum are acquired successfully by this method. The experimental results show that this method has high sensitivity and high resolution. | ZHENG SiYi GUO HongXia LI YaAn WANG BingHe ZHANG PengYi | 2007 | Chinese Science Bulletin2007，52，14： | 21 |
| 2 | Axin and Fratl interact with dvl and GSK, bridging Dvl to GSK in Wnt - mediated regulation of LEF - 1 显示文摘 | Li L Yaan H Weaver C D | 1999 | EMBO J1999，18，15： | 1 |
| 3 | Feature extraction of ship radiated-noise by 1(1/2)-spectrum显示文摘The properties of 1(1/2)-spectrum are proved and the performances are an- alyzed. By means of the spectrum, the basic frequency component of the harmonic signals can be enhanced. Gaussian color noise and symetrical distribution noise can be canceled. And non-quadratic phase coupling harmonic components in harmonic signal can be reduced. The ship radiated-noise is analyzed and its 7 features are extracted by the spectrum. By means of B-P artificial neural network, three type ships are classified according to extracted features. The classification results about the three type ships A, B and C are 90%, 91.3% and 85.7%. respectively. | FAN Yangyu, TAO Baoqi, XIONG Ke, SHANG Jiuhao, SUN Jincai, LI Yaan (The key laboratory for smart materials and structures, Nanjing University of Aeronautics & Astronautics Nanjing 210016) (Northwest University of Light Industry Xianyang 712081) (Northwest | 2002 | Chinese Journal of Acoustics2002，21，2： | 0 |
| 4 | Relationship Between Several Biochemical Indexes and Resistance of Aegilops Species to Oat-Bird Cherry Aphids(Homoptera:Aphididae)显示文摘The biochemical mechanism of resistance of 9 Aegilops species including A.biuncialis,A.juvenalis, A.ovata, A.kotschyi var. varianilis, A.triaristata, A.tauschii, A.vavilovii, A.crassa and A.ventricosa in Triticeae to oat bird cherry aphid ( Rhopalosiphum padi ) were reported for the first time. The results showed that the content of total phenols in seedling was not associated with resistance to this aphid. The level of DIMBOA was negatively related to intrinsic innate rate of increase ( r m ) of R. padi. Neither of soluable sugar nor total phenols in adult stage was associated with resistance level. However, concentrations of free proline and serine in leaf were positively related to r m of R. padi ( r m =0.0636+0.23x pro ** +1.982x ser *). The content of DIMBOA was high negatively related to r m of R. padi ( r =0.819 ** ). The low level of free proline and serine and high concentration of DIMBOA could be regarded as important elements for resistance of Aegilops species to R. padi. | LI Qing, YE Hua zhi, YANG Qun fang and JIANG Su rong (College of Agronomy, Sichuan Agricultural University, Yaan 625014, P.R.China) | 2003 | Agricultural Sciences in China2003，2，9： | 0 |
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