Research of Coal Pores and Integrity Evaluation Method Based on Fractal Theory

2014 ◽  
Vol 670-671 ◽  
pp. 258-262 ◽  
Author(s):  
Ji Li ◽  
Xin Wu
Keyword(s):  
Fractal Dimension ◽  
Coal Sample ◽  
Evaluation Method ◽  
Structural Integrity ◽  
Gas Adsorption ◽  
Fractal Theory ◽  
Physical And Mechanical Properties ◽  
Box Dimension ◽  
Sem Images ◽  
Sem Image

Coal is a natural porous media, its porosity and structural integrity influenced the gas adsorption and desorption characteristics greatly, as well as physical and mechanical properties of coal. Scanning electron microscopy (SEM) is applied to acquire SEM image of four kinds of coal samples at different zoom levels, and the box dimension can be worked out based on the pore preprocessing of SEM images. Then, the numerical value of box dimension is used to describe the development degree of the four kinds of coal sample and four development degrees’ sequence. At last, the intrinsic relevance between fractal dimension and other parameters is analyzed through mathematic method. The results show as follows: coal sample has self-similarity characteristic; the fractal dimension is related to both the total number of pores and porosity degree; the data of the coal pore, analyzed through fractal dimension, are consistent with that through traditional method; what’s more, fractal dimension has more advantages in describing accuracy and simplicity.

scholarly journals Recycled Mortars with Ceramic Aggregates. Pore Network Transmutation and Its Relationship with Physical and Mechanical Properties

Materials ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1543
Author(s):  
Francisca Guadalupe Cabrera-Covarrubias ◽  
José Manuel Gómez-Soberón ◽  
Carlos Antonio Rosas-Casarez ◽  
Jorge Luis Almaral-Sánchez ◽  
Jesús Manuel Bernal-Camacho
Keyword(s):  
Mechanical Properties ◽  
Image Analysis ◽  
Open Porosity ◽  
Gas Adsorption ◽  
Physical And Mechanical Properties ◽  
Recycled Aggregate ◽  
Bet Surface Area ◽  
Sem Image ◽  
The Relationship ◽  
Sem Image Analysis

The porosity of mortars with recycled ceramic aggregates (10, 20, 30, 50, and 100% as a replacement of natural aggregate) was evaluated and analyzed using three different techniques. The results of gas adsorption (N2), Scanning Electron Microscopy (SEM) image analysis and open porosity allowed establishing the relationship between the recycled aggregate content and the porosity of these mortars, as well as the relationship between porosity and the physical and mechanical properties of the mortars: absorption, density, compressive strength, modulus of elasticity, and drying shrinkage. Using the R2 coefficient and the equation typology as criteria, additional data such as Brunauer, Emmett, and Teller (BET) surface area (N2 adsorption) established significant correlations with the mentioned properties; with SEM image analysis, no explanatory relationships could be established; and with open porosity, revealing relationships were established (R2 > 0.9). With the three techniques, it was confirmed that the increase in porosity is related to the increase in the amount of ceramic aggregate; in particular with gas adsorption (N2) and open porosity. It was concluded that the open porosity technique can explain the behavior of these recycled mortars with more reliable data, in a simple and direct way, linked to its establishment with a more representative sample of the mortar matrix.

scholarly journals Response of Floc Networks in Cemented Paste Backfill to a Pumping Agent

Metals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1906
Author(s):  
Jiaqi Zhu ◽  
Shunchuan Wu ◽  
Haiyong Cheng ◽  
Xiaojie Geng ◽  
Jin Liu
Keyword(s):  
Fractal Dimension ◽  
Fractal Theory ◽  
Mineral Resources ◽  
Cemented Paste Backfill ◽  
Sem Image ◽  
Multi Scale ◽  
Paste Backfill ◽  
Engineering Significance ◽  
Deep Underground ◽  
Dominant Structure

Cemented paste backfill is critical for the development of green mines, the safe exploitation of mineral resources deep underground, and the efficient disposal of solid wastes produced by mining. In this paper, the mechanism underpinning how the pumping agent works was studied. The number, area, and fractal dimension of pores in the microstructure of fresh paste were quantitatively analyzed using scanning electron microscopy (SEM), image processing, and fractal theory, and the response of flocs was investigated. The results show that floc networks disintegrated and the liquid network became the dominant structure under the action of the pumping agent, which enhanced the lubrication and promotion of multi-scale particles. In addition, the force chains became fragile and scattered, diminishing the yield stress of the paste. The pores had a more homogenized dimension and the porosity was 15.52% higher. The increase in the fractal dimension of the pores indicated that there was a higher self-similarity, in terms of microstructure, with a strengthened liquid network. The migration of floc structures contributed to the enhancement of the fluidity and rheology of the paste. This study provides insights into the effects of floc and liquid networks on the performance of paste, and it is of engineering significance in terms of realizing safe and efficient CPB operations.

Effect of Glutinous Rice Paste on Compressive Strength of Lime-Stabilized Soil

2011 ◽  
Vol 280 ◽  
pp. 5-8
Author(s):  
Hong Tao Peng ◽  
Qi Zhang ◽  
Nai Sheng Li ◽  
De Fa Wang
Keyword(s):  
Compressive Strength ◽  
Soil Sample ◽  
Experimental Results ◽  
Box Dimension ◽  
Sem Images ◽  
Sem Image ◽  
Glutinous Rice ◽  
Stabilized Soil ◽  
The Difference ◽  
The One

The lime-stabilized soil was mixed with glutinous rice paste in proper proportion to determine the difference in compressive strength caused by introduction of glutinous rice paste. The experimental results show that the unconfined compressive strengths of lime-stabilized soil specimens treated with glutinous rice paste are all higher than those without treated at different curing times (7d, 28d, 40d, and 60d). The calculated fractal box dimension value of SEM image of lime stabilized soil sample is close to and slightly less than the one treated with glutinous rice paste. The SEM images show that the microstructure of lime-stabilized soil treated with glutinous rice paste is denser than that without treated. This kind of denser microstructure should be the basis of higher unconfined compressive strengths of the specimens treated with glutinous rice paste.

Study on Fractal Characteristics of Acoustic Emission in Circular Double-Layer Stirrup Confined Concrete

2014 ◽  
Vol 578-579 ◽  
pp. 359-368 ◽  
Author(s):  
Peng Fei Geng ◽  
Lin Zhu Sun ◽  
Fang Yang ◽  
Wei Li
Keyword(s):  
Acoustic Emission ◽  
Fractal Dimension ◽  
Double Layer ◽  
Fractal Theory ◽  
Equivalent Stress ◽  
Concrete Columns ◽  
Confined Concrete ◽  
Box Dimension ◽  
Emission Parameter ◽  
Fractal Characteristics

Vertical bearing capacity experiments were conducted with circular double-layer stirrup confined concrete columns as study objects, data acquisition was carried out using acoustic emission (AE) equipment and the AE parameters and graphs acquired during the experiments were analyzed to obtain the damage evolution of steel reinforced concrete columns under compression. The correlation between fractal dimension of AE graphs and curve was studied using the fractal theory, and the results show that the AE parameter graphs have fractal characteristics and the box dimension of each AE parameter graph constantly increases with the increase in stress, with a positive correlation exhibited between the fractal dimension and stress level. The loss variable expressed with fractal dimension was defined to establish actual equivalent stresses and the equivalent stress curves and experimental curves were compared; the results show that the fractal dimension of acoustic emission parameter graph can characterize the damage laws of the concrete member.

scholarly journals Research On the Fractal Dimensions of the Organic-Rich Shale Pores Via Different Models

2022 ◽  
Vol 2152 (1) ◽  
pp. 012020
Author(s):  
Fangyao Dai
Keyword(s):  
Fractal Dimension ◽  
Gas Adsorption ◽  
Fractal Theory ◽  
Fractal Dimensions ◽  
Fractal Model ◽  
Relative Pressure ◽  
Longmaxi Formation ◽  
High Relative Pressure ◽  
Adsorption Data ◽  
Different Dimensions

Abstract Fractal dimension can be used to the pore surface characterize. For pore structures in different sizes, the calculation models of fractal theory should be distinguished due to the different principles of the gas adsorption experiments. To further study the adaptability of the fractal model for gas adsorption experimental data, the author collected shale samples of Longmaxi formation from Well JY1, then CO2 and N2 adsorption provided the PSD curves. In addition, the fractal dimensions of micropore and mesopore were calculated by the Jaroniec fractal model and Frenkel–Halsey–Hill (FHH) fractal model respectively. The research shows that the Jaroniec model may be suitable to calculate CO2 adsorption data and could characterize the fractal dimension of micropore, while the FHH model may be suitable to calculate N2 adsorption data in the high relative pressure region. It suggests that the micropore and mesopore could have different dimensions and the evaluation of the structure in shale pores should consider both of them.

Research on microstructure properties of clay-sand mixtures studied by ipp and mip methods

2020 ◽  
pp. 16-23
Author(s):  
QI DAOZHENG ◽  
GU CONG ◽  
FU JIAJIA ◽  
WANG YAO
Keyword(s):  
Electron Microscopy ◽  
Image Processing ◽  
Scanning Electron Microscopy ◽  
Mercury Intrusion Porosimetry ◽  
Fractal Theory ◽  
Sand Content ◽  
Sem Images ◽  
Mercury Intrusion ◽  
Sem Image ◽  
Scanning Electron

The clay-sand mixtures with diferent partcle sizes were prepared to investgate partcle and pore characteristcs. The microstructure characteristcs of the sand-clay mixtures were studied by the Mercury Intrusion Porosimetry (MIP) test and Scanning Electron Microscopy (SEM). Image-Pro Plus (IPP) image processing sofware was used to quantfy SEM images which investgated the micro-mechanism of structural evoluton of mixtures under diferent gradatons. The research results indicate that the units of mixtures develop from platelets and honeycomb to agglomerated and granular with the increase of sand content. The contact between partcles transits from face-face contacts to edge-face and pointface contacts. This artcle evaluated the fractal characteristc of partcle and pore structure based on the fractal theory. With the increase Circularity of the partcles, the ordered arrangement of the partcles in the mixed soil is further reduced. In general, the distributon of pores changes from intergranular pores to pores in aggregate, which provides a theoretcal basis for further study on the micro-macro correlaton of mixtures.

Computer Design of Low Silicon Sinter Fractal Dimension Based on SEM Images

2012 ◽  
Vol 510 ◽  
pp. 694-697
Author(s):  
Chang Ying Zhou
Keyword(s):  
Fractal Dimension ◽  
Quantitative Methods ◽  
Fractal Theory ◽  
Practical Significance ◽  
Multiphase Medium ◽  
Computer Design ◽  
Micro Structure ◽  
Sem Images ◽  
New Ideas

Sinter as an intermediate product of the iron making, is a multiphase medium, and the microstructure of finished sinter directly affects the quality of sinter. But because the sinter micro structure of the extreme irregularities, it is difficult to use the traditional quantitative methods on the accurate description, the introduction of the fractal theory provides us with new ideas. According to the characteristics of sinter SEM photos, and used the VC++ computer programming language, it is researched and designed that the fractal dimension of calculation program (FWJS) based on the sinter SEM microscopic photos, through which got the fractal dimension value and describe the microscopic structure of the sample quantificationally, which has very important practical significance for the fractal research of sinter .

Evaluation of WEDM Surface Quality

2010 ◽  
Vol 97-101 ◽  
pp. 4080-4083 ◽  
Author(s):  
Lei Geng ◽  
Hua Yan Zhong
Keyword(s):  
Surface Roughness ◽  
Fractal Dimension ◽  
Spectral Density ◽  
Surface Topography ◽  
Surface Quality ◽  
Power Spectral Density ◽  
Evaluation Method ◽  
Fractal Theory ◽  
Machined Surface ◽  
Power Spectral

The formation of WEDM surface is a complicated process. There are many factors which make machined surface topography have the characteristics of complex and irregular, and impact using performance of parts. The work investigated microscopic features of the WEDM surface topography based on power spectral density and fractal theory, and proposed power spectral density evaluation method of the WEDM surface. The fractal dimension of the WEDM surface was calculated by structure function method. The physical meaning of the fractal dimension of the WEDM surface was described. The result shows that topography of the WEDM surface exhibits strong fractal characteristics within a certain scale. The processing parameters and pulse power performance will affect the fractal dimension D. The fractal dimension D has a certain relationship with the surface roughness Ra. It is more reasonable to use the fractal dimension D as well as the surface roughness Ra together to evaluate WEDM surface quality.

The Blemish Identify in Ultrasonic Testing of Friction Welded Joints Based on Fractal Theory

2015 ◽  
Vol 799-800 ◽  
pp. 942-946
Author(s):  
Yuan Peng Liu ◽  
Xin Yin ◽  
Min Wang
Keyword(s):  
Fractal Dimension ◽  
Welded Joints ◽  
Ultrasonic Testing ◽  
Fractal Theory ◽  
Metal Alloys ◽  
Box Dimension ◽  
Box Counting ◽  
Signal Characteristics ◽  
Box Counting Dimension ◽  
Dimension Number

The friction welded joints made by GH4169 heat metal alloys are detected by U1traPAC system of the ultrasonic wave explore instrument. Aimed at the blemish signal characteristics, a method is put forward to identify the blemish signal in ultrasonic testing of friction welded joints based on fractal theory., A new kind of fractal dimension number calculation method—normalized scale box-counting dimension method is used to calculate the box-dimension of the blemish signal, and statistic and analysis the scopes of the box-dimension of the blemish signal and the square differ of the result. The preliminary experimental results show that the blemish signal and have each fractal dimension zones, and don’t hand over to fold. So it can use to judge whether the blemish exist or not. The method is identified to have better covariance characteristics about the blemish identify of the friction welded joints.

scholarly journals Evaluation of particle size distribution of granular blasting materials based on the fractal theory

2019 ◽  
Vol 11 (10) ◽  
pp. 168781401988156 ◽  
Author(s):  
Jiejie Ji ◽  
Qiang Yao ◽  
Faming Wu ◽  
Hongtao Li
Keyword(s):  
Particle Size ◽  
Fractal Dimension ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Evaluation Method ◽  
Fractal Theory ◽  
Distribution Model ◽  
Uniformity Coefficient ◽  
Functional Relationships ◽  
Fine Grain

The particle size distribution of granular blasting materials has a vital influence on the filling quality of earth-rockfill dams. The engineering experience-based method used to evaluate the particle size distribution has shortcomings at both the theoretical and practical aspects. This article proposes a new evaluation method based on the fractal theory. Grading sieve tests on granular materials, mass fractal analysis of particle size distribution, and a probability distribution model test of the characteristic parameters are used to revise the functional relationships between the fractal dimension D and the uniformity coefficient/curvature coefficient ( Cu/ Cc) of the grading curve. The feasibility of using D to evaluate the particle size distribution and the optimal fine grain content is then analyzed and determined. According to the results, the geometric shapes of the granular blasting materials have fractal characteristics, and their particle size distribution has a fractal distribution. The ranges of D where the rockfill and transition materials have a good particle size distribution are D = 2.254–2.529 and D = 2.358–2.559, corresponding to optimal fine grain content of 1.953%–11.805% and 10.268%–23.123%, respectively. Fractal dimension has a solid theoretical basis and strong practical applicability as an evaluation index for the particle size distribution of granular blasting materials.

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