Ultrasonic imaging by fractal dimension of power spectrum shape

Author(s):  
T. Kikuchi ◽  
S. Kiryu ◽  
S. Sato
IEEE Access ◽  
2019 ◽  
Vol 7 ◽  
pp. 185879-185892
Author(s):  
Syaimaa' Solehah Mohd Radzi ◽  
Vijanth Sagayan Asirvadam ◽  
Mohd Zuki Yusoff

Geophysics ◽  
2016 ◽  
Vol 81 (4) ◽  
pp. D441-D451 ◽  
Author(s):  
Tianyang Li ◽  
Ruihe Wang ◽  
Zizhen Wang ◽  
Yuzhong Wang

Fractures greatly increase the difficulty of oil and gas exploration and development in reservoirs consisting of interlayered carbonates and shales and increase the uncertainty of highly efficient development. The presence of fractures or layered media is also widely known to affect the elastic properties of rocks. The combined effects of fractures and layered media are still unknown. We have investigated the effects of fracture structure on wave propagation in interlayered carbonate and shale rocks using physical models based on wave theory and the similarity principle. We have designed and built two sets of layered physical models with randomly embedded predesigned vertically aligned fractures according to the control variate principle. We have measured the P- and S-wave velocities and attenuation and analyzed the effects of fracture porosity and aspect ratio (AR) on velocity, attenuation, and power spectral dimension of the P- and S-waves. The experimental results indicated that under conditions of low porosity ([Formula: see text]), Han’s empirical velocity-porosity relations and Wang’s attenuation-porosity relation combined with Wyllie’s time-average model are a good prediction for layered physical models with randomly embedded fractures. When the porosity is constant, the effect of different ARs on elastic wave properties can be described by a power law function. We have calculated the power spectrum fractal dimension [Formula: see text] of the transmitted signal in the frequency domain, which can supplement the S-wave splitting method for estimating the degree of anisotropy. The simple power law relation between the power spectrum fractal dimension of the P-waveform and fracture density suggests the possible use of P-waves for discriminating fracture density. The high precision and low error of this processing method give new ideas for rock anisotropy evaluation and fracture density prediction when only P-wave data are available.


1993 ◽  
Vol 5 (2) ◽  
pp. 198-201
Author(s):  
Hideto Ide ◽  
◽  
Shinjiro Yagi

We have tried to apply fractal analysis to time series which have 1/f power spectrum. Before carrying out any analysis, we expand the idea of fractal to time series. We examine the fractal dimension of time series to simulate the Brawnian function. We apply fractal analysis to observational data of event related potential (ERP) and compare averaging results with those based on fractal analysis.


2021 ◽  
Vol 27 (3) ◽  
pp. 71-77
Author(s):  
Georgios Pouraimis ◽  
Apostolos Kotopoulis ◽  
Basil Massinas ◽  
Panayiotis Frangos

This paper presents a novel method of sea state characterization by using four criteria, which are applied to normalized experimental Synthetic Aperture Radar (SAR) one–dimensional signatures (range profiles), provided to our research group by SET 215 Working Group on “SAR radar techniques”. These criteria are the “Fractal Dimension”, “Fractal Length”, “Variance σ2”, and “Power Spectrum Density - Least Squares”. The “Fractal Dimension” and “Fractal Length” criteria, which appear to be the most important out of the four criteria, use the “blanket” technique to provide sea state characterization from SAR radar range profiles. It is based on the calculation of the area of a “blanket”, corresponding to the range profile under examination, and then on the calculation of the corresponding “Fractal Dimension” and “Fractal Length” of the range profile. The main idea concerning this proposed technique is the fact that normalized SAR radar range profiles, corresponding to different sea states, produce different values of “Fractal Dimension” and “Fractal Length” for all angles of incidence examined here. As a result, a sea state characterization technique for two different sea states (turbulent and calm sea) is presented in this paper.


1995 ◽  
Vol 34 (Part 1, No. 5B) ◽  
pp. 2831-2834 ◽  
Author(s):  
Tsuneo Kikuchi ◽  
Toshihiro Nakazawa ◽  
Tetsuo Furukawa ◽  
Toshiyuki Higuchi ◽  
Yukio Maruyama ◽  
...  

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