scholarly journals Recursive formula for the peak delay time with travel distance in von Kármán type non-uniform random media on the basis of the Markov approximation

2008 ◽  
Vol 173 (2) ◽  
pp. 534-545 ◽  
Author(s):  
Tsutomu Takahashi ◽  
Haruo Sato ◽  
Takeshi Nishimura
Keyword(s):  
Delay Time ◽  
Random Media ◽  
Recursive Formula ◽  
Travel Distance ◽  
Markov Approximation ◽  
Von Karman ◽  
Von Kármán

Constructing Von Karman Random Media Model with Power Spectrum Method

2014 ◽  
Vol 536-537 ◽  
pp. 911-914
Author(s):  
Ning Yang ◽  
Xu Qian
Keyword(s):  
Power Spectrum ◽  
Frequency Domain ◽  
Random Media ◽  
Correlation Lengths ◽  
Spectrum Method ◽  
Inverse Fourier Transformation ◽  
Von Karman ◽  
Auto Correlation Function ◽  
Power Spectrum Method ◽  
Von Kármán

In this paper, Von Karman random media is constructed with power spectrum method. The random media with Von Karman autocorrelation cannot be constructed in time domain but in frequency domain. So power spectrum method is utilized to solve the problem. The spectrum of random function is generated in frequency domain with random field and auto-correlation function. With inverse Fourier transformation, the Von Karman random media model is constructed. With different correlation lengths, six group of Von Karman random media are constructed.

Study on the Scattering Effect of Micro-Scale Inhomogeneity to the Elastic Wave

2013 ◽  
Vol 807-809 ◽  
pp. 2228-2231
Author(s):  
Ning Yang ◽  
Xu Qian
Keyword(s):  
Random Media ◽  
Random Medium ◽  
Wave Length ◽  
Seismic Record ◽  
Obvious Effect ◽  
Von Karman ◽  
Scale Inhomogeneity ◽  
Von Kármán ◽  
Dielectric Objects ◽  
The Impact

Some research on the wave propagation in random medium with Von Karman correlation has been developed in this paper. It focuses on the seismic record of circular disturbance in random medium with Von Karman autocorrelation function. Six different kinds of random medium become the background of the dielectric object. The study of the impact to the responds of the dielectric objects can be measured by applying the FDTD to random background medium model. The numerical results show that the random media make the most obvious effect when the scale of imhomogeneity is close to the wave length.

scholarly journals The two-dimensional hydrodynamical theory of moving aerofoils. IV

1947 ◽  
Vol 188 (1015) ◽  
pp. 439-463
Keyword(s):  
Stability Problem ◽  
Two Dimensional ◽  
Centre Of Gravity ◽  
First Approximation ◽  
Von Karman ◽  
Moving Cylinder ◽  
Period Equation ◽  
The Stability ◽  
Von Kármán ◽  
Hydrodynamical Theory

In the first part of this paper opportunity has been taken to make some adjustments in certain general formulae of previous papers, the necessity for which appeared in discussions with other workers on this subject. The general results thus amended are then applied to a general discussion of the stability problem including the effect of the trailing wake which was deliberately excluded in the previous paper. The general conclusion is that to a first approximation the wake, as usually assumed, has little or no effect on the reality of the roots of the period equation, but that it may introduce instability of the oscillations, if the centre of gravity of the element is not sufficiently far forward. During the discussion contact is made with certain partial results recently obtained by von Karman and Sears, which are shown to be particular cases of the general formulae. An Appendix is also added containing certain results on the motion of a vortex behind a moving cylinder, which were obtained to justify certain of the assumptions underlying the trail theory.

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