Modeling of the power spectrum density of an entirely randomized modulation in power converters

The response of a large-size cooling tower with 250m high subjected to the seismic action are investigated by both random vibration theory and response spectrum method. Shell element is taken to model the tower body, and beam element is used for the circular foundation and supporting columns. The earthquake motion input is a colored filtered white noise model and mode superposition method is adopted to analyze the random response of the large-size cooling tower. The paper presents the power spectrum density functions (PDF) and standard deviation of the displacement of the top and characteristic node, and the analysis results indicate that the results of the stationary random vibration theory and the response spectrum method are the same order of magnitude. The power spectrum density function of the bottom node stress is obviously bigger than the one at the top and the throat, and the random response of meridonal stress is dominated at the top. In addition, the peak frequency position of the power spectrum density function is different from the corresponding stress.

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Improved Noise Power Spectrum Density Estimation for Binaural Hearing Aids Operating in a Diffuse Noise Field Environment

IEEE Transactions on Audio Speech and Language Processing ◽

10.1109/tasl.2008.2009017 ◽

2009 ◽

Vol 17 (4) ◽

pp. 521-533 ◽

Cited By ~ 39

Author(s):

A.H. Kamkar-Parsi ◽

M. Bouchard

Keyword(s):

Power Spectrum ◽

Density Estimation ◽

Hearing Aids ◽

Binaural Hearing ◽

Power Spectrum Density ◽

Noise Power ◽

Field Environment ◽

Spectrum Density ◽

Binaural Hearing Aids ◽

Diffuse Noise

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The Time Domain Simulation of Non-Stationary Road Roughness

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.423-426.1238 ◽

2013 ◽

Vol 423-426 ◽

pp. 1238-1242

Author(s):

Hao Wang ◽

Xiao Mei Shi

Keyword(s):

Power Spectrum ◽

Time Domain ◽

Ride Comfort ◽

Time History ◽

Random Excitation ◽

Power Spectrum Density ◽

The Road ◽

Road Roughness ◽

Spectrum Density ◽

History Of

The input of road roughness, which affects the ride comfort and the handling stability of vehicle, is the main excitation for the running vehicle. The time history of the road roughness was researched with the random phases, based on the stationary power spectrum density of the road roughness determined by the standards. Through the inverse Fourier transform, the random phases can be used to get the road roughness in time domain, together with the amplitude. Then, the time domain simulation of the non-stationary random excitation when the vehicle ran at the changing speed, would also be studied based on the random phases. It is proved that the random road excitation for the vehicle with the changing speed is stationary modulated evolution random excitation, and its power spectrum density is the stationary modulated evolutionary power spectrum density. And the numerical results for the time history of the non-stationary random inputs were also provided. The time history of the non-stationary random road can be used to evaluate the ride comfort of the vehicle which is running at the changing speed.

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