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The near field acoustic holography technique for cyclostationary sound field and its experimental research

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Chinese Journal of Acoustics 2005年第3期24卷 263-270页

作者： WANQuan JIANGWeikang statekeylaboratoryofvibration Shock&NoiseShanghaiJiaotongUniversityShanghai200240

One near field acoustic holography (NAH) technique is proposed for analyzing cyclostationary sound field. The signal of this kind of sound field has very serious modulation phenomenon generally, in spectrum of which obvious sidebands exist. It is difficult for the traditional NAH to possess demodulation function, so virtual power of sidebands exists in its hologram. Replacing the Fourier's transform with the second-order cyclic statistics, the proposed NAH technique uses the cyclic spectrum density (CSD) function as reconstructed physical quantity, instead of the spectrum or power spectrum density of sound pressure signal. The CSD function can demodulate cyclostationary signals, which makes no virtual power of sidebands in its hologram. The results of simulation and experiment show that the proposed NAH can extract more information about cyclostationary sound field than traditional NAH, by which sound field can be known more clearly.

关键词： The near field acoustic holography technique for cyclostationary sound field and its experimental research

Interleaving distribution of multifractal strength of 16-channel EEG signals

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Chinese Science Bulletin 2003年第16期48卷 1700-1703页

作者： WANGWei NINGXinbao WANGJun ZHANGSheng CHENJie LILejia InstituteforBiomedicalElectronicEngineering instituteofAcousticsandDepartmentofElectronicScience&EngineeringNanjingUniversityNanjing210093China DepartmentofPhysics NanjingNormalUniversityNanjing210097China statekeylaboratoryofvibration Shock&NoiseShanghaiJiaotongUniversityShanghai300030China ElectroencephalogramOffice NanjingBrainHospitalNanjing210023China

Multifractal characteristics of 16-channel hu-man electroencephalogram (EEG) signals under eye-closed rest are analyzed for the first time. The result shows that the EEGs from the different sites on the scalp have different multifractal characteristics and the multifractal strength value a exhibits a kind of interleaving and left-right oppo-site distribution on scalp. This distribution rule is consistent with the localization of function and the lateralization theory in physiology. So Da can become an effective parameter to describe the brain potential character. And such a a stable distribution rule on sites of the scalp means a classic cerebral cortex active state.

关键词：脑电图大脑皮层分布规律脑电波信号生理学参数活动状态非线性动力学

Crashworthiness simulation and improvement design of auto-body based on finite element mehtod

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Journal of Systems Engineering and Electronics 2004年第4期15卷 741-746页

作者： ZhangXiaoyun JinXianlong QiWenguo SunYi ZhouChangying WangShida HighPerformanceComputingCenter ShanghaiJiaotongUniversityShanghai200030P.R.China HighPerformanceComputingCenter ShanghaiJiaotongUniversityShanghai200030P.R.China//StateKeyLaboratoryofVibrationShock&NoiseShanghaiJiaotongUniversityShanghai200030P.R.China ShanghaiAutomotiveIndustryTechnicalCenter Shanghai200090P.R.China

One developing commercial vehicle was simulated on crashworthiness using the nonlinear finite element method. The deformation of the auto-body, the movement of the steering wheel and the dynamic responses of the occupant at the initial velocity of 50 km/h were studied. The results show that the design of the vehicle could be improved on structure and material. The frontal longitudinal beam, the main energy-absorbing part of the auto-body, was optimized on structure. The data of the simulation predict that the hinge of the engine hood would fracture during the crash. The failure of the engine hood hinge would be a danger to both the driver and passengers. Then the problem was solved by changing the engine hood and hinge on structure and material. Simulation results also show that applying new material and new manufacture techniques could improve the crashworthiness of the vehicle greatly. These improvement methods are valuable to the virtual design of vehicles.

关键词： Vehicles Vehicle crash testing Engines Finite element methods Fasteners Computer crashes Materials

The statistical distributed source boundary point method to calculate the acoustic radiation from the random vibrating body

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Chinese Journal of Acoustics 2003年第4期22卷 369-377页

作者： WANGXiufeng CHENXinzhao LIUZhao statekeylaboratoryofvibration Shock~zNoiseShanghaiJiaotongUniversityShanghai200030 SchoolofMechanicalandAutomobileEngineering HefeiUniversityofTechnologyHefei230009 MechanicalEngineeringDepartment TongjiUniversityShanghai200092

The statistical distributed source boundary point method (SDSBPM) put forward is applied to calculate the acoustic radiation from the random vibrating body. A detailed description of this method is presented. A test for the SDSBPM is carried out through the random vibrating sphere and the random vibrating cuboid. An experiment on the exterior acoustic radiation of a random vibrating sirnulation axial box of the lathe tool is performed in a semi-anechoic chamber.

关键词：舟山出口