Fractal Analysis of Positive Streamer Patterns in Transformer Oil-Based TiO2Nanofluid

2017 ◽  
Vol 45 (7) ◽  
pp. 1704-1709 ◽  
Author(s):  
Yuzhen Lv ◽  
Yang Ge ◽  
Qian Du ◽  
Qian Sun ◽  
Bingliang Shan ◽  
...  
Keyword(s):  
Fractal Analysis ◽  
Transformer Oil ◽  
Positive Streamer

The effects of shallow traps on the positive streamer electrodynamics in transformer oil based nanofluids

2018 ◽  
Vol 51 (10) ◽  
pp. 105304 ◽  
Author(s):  
You Zhou ◽  
Sanyi Sui ◽  
Jie Li ◽  
Zigui Ouyang ◽  
Yuzhen Lv ◽  
...  
Keyword(s):  
Transformer Oil ◽  
Shallow Traps ◽  
Positive Streamer

scholarly journals Finite Element Based Comparative Analysis of Positive Streamers in Multi Dispersed Nanoparticle Based Transformer Oil

2021 ◽  
Vol 12 (1) ◽  
pp. 29-44
Author(s):  
Mihir Bhatt ◽  
Praghnesh Bhatt
Keyword(s):  
Electron Density ◽  
Dielectric Strength ◽  
Space Charge Density ◽  
Transformer Oil ◽  
Ionization Region ◽  
Streamer Propagation ◽  
Positive Streamers ◽  
Al2o3 Nps ◽  
The Impact ◽  
Positive Streamer

The dispersion of dissimilar nanoparticles (NPs) in transformer oil (TO) has a major impact on fast propagating positive streamers. This work investigates the positive streamer dynamics in TO modified by dispersing both Fe3O4 and Al2O3 NPs at a homogenous concentration. The hydrodynamic drift diffusion model of positive streamer evolution and propagation are solved using the commercial software package COMSOL Multiphysics. The impact of multiple NPs (MNPs) has been analysed for streamer propagation, electric field intensity, electron density, and space charge density of modified TO. MNPs successfully reduce streamer propagation velocity by 50%, 17%, and 37.5% comparing to pure oil, Fe3O4 based nanodielectric fluids (NDFs), and Al2O3 based NDFs, respectively. The spatial distribution of electron density reveals the loss of electrons from the ionization region until the saturation of NPs. A comparative study demonstrates that MNPs significantly alter the streamer dynamics and augment the dielectric strength of TO compared to individual NPs.

scholarly journals Effect of Fe3O4 nanoparticles on positive streamer propagation in transformer oil

AIP Advances ◽  
2016 ◽  
Vol 6 (3) ◽  
pp. 035110 ◽  
Author(s):  
Yuzhen Lv ◽  
Qi Wang ◽  
You Zhou ◽  
Chengrong Li ◽  
Yang Ge ◽  
...  
Keyword(s):  
Fe3o4 Nanoparticles ◽  
Transformer Oil ◽  
Streamer Propagation ◽  
Positive Streamer

Heterogeneity of Cerebral Blood Flow: a Fractal Approach

2000 ◽  
Vol 39 (02) ◽  
pp. 37-42 ◽  
Author(s):  
P. Hartikainen ◽  
J. T. Kuikka
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Fractal Dimension ◽  
Frontal Lobe ◽  
Fractal Analysis ◽  
Relative Dispersion ◽  
Emission Computed Tomography ◽  
Brain Blood Flow ◽  
Healthy Controls ◽  
Fractal Approach

Summary Aim: We demonstrate the heterogeneity of regional cerebral blood flow using a fractal approach and singlephoton emission computed tomography (SPECT). Method: Tc-99m-labelled ethylcysteine dimer was injected intravenously in 10 healthy controls and in 10 patients with dementia of frontal lobe type. The head was imaged with a gamma camera and transaxial, sagittal and coronal slices were reconstructed. Two hundred fifty-six symmetrical regions of interest (ROIs) were drawn onto each hemisphere of functioning brain matter. Fractal analysis was used to examine the spatial heterogeneity of blood flow as a function of the number of ROIs. Results: Relative dispersion (= coefficient of variation of the regional flows) was fractal-like in healthy subjects and could be characterized by a fractal dimension of 1.17 ± 0.05 (mean ± SD) for the left hemisphere and 1.15 ± 0.04 for the right hemisphere, respectively. The fractal dimension of 1.0 reflects completely homogeneous blood flow and 1.5 indicates a random blood flow distribution. Patients with dementia of frontal lobe type had a significantly lower fractal dimension of 1.04 ± 0.03 than in healthy controls. Conclusion: Within the limits of spatial resolution of SPECT, the heterogeneity of brain blood flow is well characterized by a fractal dimension. Fractal analysis may help brain scientists to assess age-, sex- and laterality-related anatomic and physiological changes of brain blood flow and possibly to improve precision of diagnostic information available for patient care.

Air Pollution Attributable Deaths: A Global View Through Fractal Analysis

2014 ◽  
Vol 2 (1) ◽  
pp. 149-162
Author(s):  
Melvin de Castro ◽  
◽  
Tonette Villanueva ◽  
Grace Arcamo ◽  
Rayna Lynn de Castro ◽  
...  
Keyword(s):  
Air Pollution ◽  
Fractal Analysis ◽  
Global View

Structure characterization of ground calcium carbonate flocs by fractal analysis and their effects on handsheet properties

TAPPI Journal ◽  
2013 ◽  
Vol 12 (3) ◽  
pp. 17-23 ◽  
Author(s):  
WANHEE IM ◽  
HAK LAE LEE ◽  
HYE JUNG YOUN ◽  
DONGIL SEO
Keyword(s):  
Fractal Analysis ◽  
Structural Characteristics ◽  
Fractal Dimensions ◽  
Strength Loss ◽  
Structure Characterization ◽  
Uniform Size ◽  
Cross Sectional ◽  
Floc Size ◽  
Mass Fractal ◽  
Handsheet Properties

Preflocculation of filler particles before their addition to pulp stock provides the most viable and practical solution to increase filler content while minimizing strength loss. The characteristics of filler flocs, such as floc size and structure, have a strong influence on preflocculation efficiency. The influence of flocculant systems on the structural characteristics of filler flocs was examined using a mass fractal analysis method. Mass fractal dimensions of filler flocs under high shear conditions were obtained using light diffraction spectroscopy for three different flocculants. A single polymer (C-PAM), a dual cationic polymer (p-DADMAC/C-PAM) and a C-PAM/micropolymer system were used as flocculants, and their effects on handsheet properties were investigated. The C-PAM/micropolymer system gave the greatest improvement in tensile index. The mass fractal analysis showed that this can be attributed to the formation of highly dense and spherical flocs by this flocculant. A cross-sectional analysis of the handsheets showed that filler flocs with more uniform size were formed when a C-PAM/micropolymer was used. The results suggest that a better understanding of the characteristics of preflocculated fillers and their influence on the properties of paper can be gained based on a fractal analysis.

Abrasive fatigue wear rubber lining in the context of fractal analysis

2019 ◽  
pp. 103-110
Author(s):  
A.S. Kobets ◽  
◽  
V.I. Dyrda ◽  
Ye.V. Kalhankov ◽  
I.M. Tsanidi ◽  
...  
Keyword(s):  
Fractal Analysis ◽  
Fatigue Wear ◽  
Rubber Lining
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