Treating Uncertainties in Multibody Dynamic Systems Using a Polynomial Chaos Spectral Decomposition

2004 ◽  
Author(s):  
Corina Sandu ◽  
Adrian Sandu ◽  
Brendan J. Chan ◽  
Mehdi Ahmadian
Keyword(s):  
Frequency Domain ◽  
Dynamic Systems ◽  
Time Domain ◽  
Spectral Decomposition ◽  
Polynomial Chaos ◽  
Model Uncertainties ◽  
Dynamic Simulations ◽  
Computational Tools ◽  
Model Complex ◽  
Multibody Dynamic

This study addresses the critical need for computational tools to model complex nonlinear multibody dynamic systems in the presence of parametric and external uncertainty. Polynomial chaos has been used extensively to model uncertainties in structural mechanics and in fluids, but to our knowledge they have yet to be applied to multibody dynamic simulations. We show that the method can be applied to quantify uncertainties in time domain and frequency domain.

Application of Multi-Seismic Attributes Analysis in Prospective Oil and Gas Area Evaluation

2013 ◽  
Vol 868 ◽  
pp. 150-153 ◽  
Author(s):  
Xu Tao Li
Keyword(s):  
Frequency Domain ◽  
Time Domain ◽  
Spectral Decomposition ◽  
Oil And Gas ◽  
Time Window ◽  
Seismic Attributes ◽  
Decomposition Technique ◽  
Gas Distribution ◽  
Good Relationship ◽  
Seismic Waveform

Seismic attributes analysis were used to predict the sand distribution in this paper. Spectral decomposition technique was carried out in frequency domain. Spectral seismic attributes made an identification of target geological-mass from time domain to frequency domain in Lower U sandstone of HMO 3D area. The 40hz frequency attribute was the best attribute to predict sand distribution. Seismic waveform classification for Lower U sandstone with the time window from-7ms to +7ms of Lower U sandstone had a good relationship with the sandstone distribution. With the comprehansive analysis of borehole oil and gas distribution and seismic attributes characteristics, a prospective oil and gas area target was determined.

scholarly journals An Alternating Frequency/Time Domain Method for Calculating the Steady-State Response of Nonlinear Dynamic Systems

1989 ◽  
Vol 56 (1) ◽  
pp. 149-154 ◽  
Author(s):  
T. M. Cameron ◽  
J. H. Griffin
Keyword(s):  
Steady State ◽  
Frequency Domain ◽  
Dynamic Systems ◽  
Time Domain ◽  
Nonlinear Dynamic ◽  
Nonlinear Dynamic Systems ◽  
System Response ◽  
Steady State Response ◽  
State Response ◽  
The Time Domain

A method is proposed for analyzing the steady-state response of nonlinear dynamic systems. The method iterates to obtain the discrete Fourier transform of the system response, returning to the time domain at each iteration to take advantage of the ease in evaluating nonlinearities there—rather than analytically describing the nonlinear terms in the frequency domain. The updated estimates of the nonlinear terms are transformed back into the frequency domain in order to continue iterating on the frequency spectrum of the steady-state response. The method is demonstrated by solving a problem with friction damping in which the excitation has multiple discrete frequencies.

scholarly journals Research on the Statistical Characteristics of Crosstalk in Naval Ships Wiring Harness Based on Polynomial Chaos Expansion Method

2017 ◽  
Vol 24 (s2) ◽  
pp. 205-214
Author(s):  
Yaodan Chi ◽  
Bin Li ◽  
Xiaotian Yang ◽  
Tianhao Wang ◽  
Kaiyu Yang ◽  
...  
Keyword(s):  
Frequency Domain ◽  
Time Domain ◽  
Electromagnetic Compatibility ◽  
Polynomial Chaos ◽  
Expansion Method ◽  
Polynomial Chaos Expansion ◽  
Statistical Characteristics ◽  
Chaos Expansion ◽  
Wiring Harness ◽  
Mc Method

Abstract Crosstalk in wiring harness has been studied extensively for its importance in the naval ships electromagnetic compatibility field. An effective and high-efficiency method is proposed in this paper for analyzing Statistical Characteristics of crosstalk in wiring harness with random variation of position based on Polynomial Chaos Expansion (PCE). A typical 14-cable wiring harness was simulated as the object of research. Distance among interfering cable, affected cable and GND is synthesized and analyzed in both frequency domain and time domain. The model of naval ships wiring harness distribution parameter was established by utilizing Legendre orthogonal polynomials as basis functions along with prediction model of statistical characters. Detailed mean value, mean square error, probability density function and reasonable varying range of crosstalk in naval ships wiring harness are described in both time domain and frequency domain. Numerical experiment proves that the method proposed in this paper, not only has good consistency with the MC method can be applied in the naval ships EMC research field to provide theoretical support for guaranteeing safety, but also has better time-efficiency than the MC method. Therefore, the Polynomial Chaos Expansion method.

JOINT INTERPRETATION OF AIRBORNE ELECTROMAGNETIC DATA IN THE TIME DOMAIN AND FREQUENCY DOMAIN

2018 ◽  
Vol 12 (7-8) ◽  
pp. 76-83
Author(s):  
E. V. KARSHAKOV ◽  
J. MOILANEN
Keyword(s):  
Fourier Transform ◽  
Frequency Domain ◽  
Time Domain ◽  
Frequency Interval ◽  
Single Spectrum ◽  
Simultaneous Inversion ◽  
Homogeneous Half Space ◽  
Time Domain Data ◽  
The Time Domain

Тhe advantage of combine processing of frequency domain and time domain data provided by the EQUATOR system is discussed. The heliborne complex has a towed transmitter, and, raised above it on the same cable a towed receiver. The excitation signal contains both pulsed and harmonic components. In fact, there are two independent transmitters operate in the system: one of them is a normal pulsed domain transmitter, with a half-sinusoidal pulse and a small "cut" on the falling edge, and the other one is a classical frequency domain transmitter at several specially selected frequencies. The received signal is first processed to a direct Fourier transform with high Q-factor detection at all significant frequencies. After that, in the spectral region, operations of converting the spectra of two sounding signals to a single spectrum of an ideal transmitter are performed. Than we do an inverse Fourier transform and return to the time domain. The detection of spectral components is done at a frequency band of several Hz, the receiver has the ability to perfectly suppress all sorts of extra-band noise. The detection bandwidth is several dozen times less the frequency interval between the harmonics, it turns out thatto achieve the same measurement quality of ground response without using out-of-band suppression you need several dozen times higher moment of airborne transmitting system. The data obtained from the model of a homogeneous half-space, a two-layered model, and a model of a horizontally layered medium is considered. A time-domain data makes it easier to detect a conductor in a relative insulator at greater depths. The data in the frequency domain gives more detailed information about subsurface. These conclusions are illustrated by the example of processing the survey data of the Republic of Rwanda in 2017. The simultaneous inversion of data in frequency domain and time domain can significantly improve the quality of interpretation.

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