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Articles 1 - 17 of 17
Full-Text Articles in Physical Sciences and Mathematics
Mechanical Behavior And Failure Response Characteristics Of Hard Sandstones Considering Bedding Dip Angles, Song Zhanping, Liu Hongke, Zheng Fang, Cheng Yun, Sun Yinhao, Song Wanxue
Mechanical Behavior And Failure Response Characteristics Of Hard Sandstones Considering Bedding Dip Angles, Song Zhanping, Liu Hongke, Zheng Fang, Cheng Yun, Sun Yinhao, Song Wanxue
Coal Geology & Exploration
This study focuses on the mechanical behavior and failure responses of hard sandstones considering bedding dip angles. Through uniaxial compression tests of hard sandstones with different bedding dip angles, this study delved into the influence of bedding dip angles on the mechanical behavior of hard sandstones and the relationship between the bedding dip angles and fractal characteristics of hard sandstone fragments. The test results show that bedding dip angles produced negligible effects on the type of the stress-strain curves of hard sandstones. However, low dip angles (0°, 22.5°, and 45°) corresponded to unimodal curves, while high dip angles (67.5° and …
Fractal Theory-Based Permeability Model Of Fracture Networks In Coals, Xia Binwei, Liao Chuanbin, Luo Yafei, Ji Kainan
Fractal Theory-Based Permeability Model Of Fracture Networks In Coals, Xia Binwei, Liao Chuanbin, Luo Yafei, Ji Kainan
Coal Geology & Exploration
Fractures in coal reservoirs, which act as the major seepage pathways for coalbed methane (CBM), determine the permeability and CBM productivity of coal reservoirs. Research on the relationships between fracture structures and reservoir permeability is of great theoretical and practical significance for the accurate prediction of CBM productivity. Based on the classical cubic law-based permeability model, as well as the fractal theory, fracture network structures, and effective stress, this study built a permeability model containing complex bending fractures, which was then combined with the S & D (Shi-Durucan) model to build the permeability model of fractured coals under the action …
Influencing Mechanisms Of Sc-Co2 Extraction On The Microstructures Of High-Rank Tectonic Coals, Zhang Xiaodong, Zhang Yu, Zhang Shuo, Li Guizhong, Li Xianzhong
Influencing Mechanisms Of Sc-Co2 Extraction On The Microstructures Of High-Rank Tectonic Coals, Zhang Xiaodong, Zhang Yu, Zhang Shuo, Li Guizhong, Li Xianzhong
Coal Geology & Exploration
This study aims to reveal the influencing patterns of supercritical CO2 (SC-CO2) on the microstructures of tectonic coals during the injection of CO2 into deep coal seams. The study conducted SC-CO2 extraction experiments on two types of high-rank coal samples with different damage degrees, namely the lean coal samples from the Daping coal mine in Shanxi Province and the anthracite samples from the Zhenxing coal mine in Guizhou Province. Accordingly, this study compared the parameters of pore structures and aromatic carbon stacking structures in the coal samples before and after the extraction experiments. Finally, this …
Structural Characteristics Of Adsorption Pores In Low-Rank Coals And Their Effects On Methane Adsorption Performance, Li Shugang, Zhou Yuxuan, Hu Biao, Qin Xueyan, Kon Xiangguo, Bai Yang, Zhang Jingfei
Structural Characteristics Of Adsorption Pores In Low-Rank Coals And Their Effects On Methane Adsorption Performance, Li Shugang, Zhou Yuxuan, Hu Biao, Qin Xueyan, Kon Xiangguo, Bai Yang, Zhang Jingfei
Coal Geology & Exploration
The study of the CH4 adsorption characteristics of low-rank coals is of great significance for gas content prediction, gas drainage, and hazard prevention. Therefore, this study selected six typical low-rank coal samples from coal mines in Shaanxi Province, on which low-temperature N2 adsorption experiments, low-pressure CO2 adsorption experiments, and CH4 isothermal adsorption experiments were carried out. As a result, the structural characteristics of adsorption pores in low-rank coals were obtained. Moreover, this study quantitatively characterized the relationships between the parameters of CH4 adsorption characteristics and those of adsorption pore structure using the micropore filling and …
Mechanical Properties And Impact Energy Index Of Coal Affected By Gas Pressure And Evolutionary Mechanism, Ding Xin, Xiao Xiaochun, Pan Yishan
Mechanical Properties And Impact Energy Index Of Coal Affected By Gas Pressure And Evolutionary Mechanism, Ding Xin, Xiao Xiaochun, Pan Yishan
Coal Geology & Exploration
The frequent occurrence of gas emission and outburst accidents caused by rock bursts in deep coal seams poses a great threat to safe underground production. Therefore, clarifying the evolution law of the mechanical properties and burst potential of gas on coal and rock is the basis for establishing effective prevention and control measures. Using the self-developed visual coal fluid-solid coupling test system, we carried out the physical experiment to study the gas adsorption, mechanical properties and fragment distribution of coal affected by gas pressure, and analyzed the evolution characteristics and mechanism of the bursting energy index. The results show that …
Study On The Effect Of Coal Microscopic Pore Structure To Its Spontaneous Combustion Tendency, Xianwei Dong, Gaojing Li, Xuanmeng Dong, Fusheng Wang
Study On The Effect Of Coal Microscopic Pore Structure To Its Spontaneous Combustion Tendency, Xianwei Dong, Gaojing Li, Xuanmeng Dong, Fusheng Wang
Journal of Sustainable Mining
Coal is a porous medium. Due to the large number of pores in coal and the pore size on its surface, usually ranging from millimeter to nanometer, it is difficult to measure and analyze the microscopic pore structure of coal. In order to investigate the effect of the microscopic pore structure of coal on its spontaneous combustion tendency, coal samples from different coal mines of the Kailuan Group were selected as the research objects, and the data of the microscopic pore distribution of three different coal samples were measured by using mercury injection apparatus. The regression analysis of microscopic pore …
Effect Of Load On Adsorption Characteristics Of Remolded Coal, Dai Juhua, Wang Zhaofeng, Li Xuechen, Li Yanfei, Yue Jiwei
Effect Of Load On Adsorption Characteristics Of Remolded Coal, Dai Juhua, Wang Zhaofeng, Li Xuechen, Li Yanfei, Yue Jiwei
Coal Geology & Exploration
In view of the difficulty in preparing the coal with broken soft structure intact, it needs to be processed into remolded coal. In order to study the influence of suppression loads on the physical characteristics of coal, the micro-pore structure and adsorption characteristics of remolded coal under different molding loads were discussed based on the pore test experiment of low temperature liquid nitrogen and the methane adsorption experiment of high pressure capacity method. The results show that: The pore volume of micropores and pores decreases slightly with the increase of molding load, the specific surface area increases slightly with the …
Micro-Pore Structure And Fractal Characteristics Of Terrestrial Shales: A Case Study Of Shahezi Formation In Xujiaweizi Fault Depression, Lin Zizhi, Lu Shuangfang, Chang Xiangchun, Li Junqian, Zhang Pengfei, Zhou Nengwu, Zhang Yu, Wang Junjie, Huang Hongsheng
Micro-Pore Structure And Fractal Characteristics Of Terrestrial Shales: A Case Study Of Shahezi Formation In Xujiaweizi Fault Depression, Lin Zizhi, Lu Shuangfang, Chang Xiangchun, Li Junqian, Zhang Pengfei, Zhou Nengwu, Zhang Yu, Wang Junjie, Huang Hongsheng
Coal Geology & Exploration
The pore structure and fractal characteristics of shale are analyzed, and their impacting factors are also revealed using the low temperature nitrogen adsorption-desorption method, combined with scanning electron microscopy, C-S analysis and XRD. The results showed that the mineral compositions of Shahezi Formation continental shales were dominated by clay minerals, quartz and feldspar. The pore types in shales were mainly clay mineral intragranular pores, feldspar dissolution pores and grain edge pore, while the organic pores were not developed. The adsorption isotherms of shales belonged to the type Ⅳ isotherm according to the IUPAC, which develop two types of hysteresis loop, …
Dem Clustering Simplification Algorithm Based On Fractal Dimension, Zhang Fan, Xiaoyang Li, Liu Huan, Hu Wei, Li Wei
Dem Clustering Simplification Algorithm Based On Fractal Dimension, Zhang Fan, Xiaoyang Li, Liu Huan, Hu Wei, Li Wei
Journal of System Simulation
Abstract: Fractal is the essential characteristic of natural scenes. It can describe the irregular extent of surface topography, so it is used for digital terrain generation. As the inverse process of terrain generation, digital terrain simplification usually uses geometric properties such as curvature index as a measure to reduce the grid to improve the efficiency of electromagnetic solver calculations, flood modeling, visual simulation and other issues, while ignoring the fractal nature of the terrain features. Since a traditional simplification algorithm of DEM is difficult to identify the characteristics of complex topography, a new clustering simplification algorithm based on fractal dimension …
Creep Acoustic Emission And Fractal Characteristics Of Coal Rock Under High Temperature Pre-Damage, Shi Hongcai
Creep Acoustic Emission And Fractal Characteristics Of Coal Rock Under High Temperature Pre-Damage, Shi Hongcai
Coal Geology & Exploration
The thermal damage and triaxial creep acoustic emission experiments of coal samples at different temperatures were carried out to investigate and analyze the mechanical characteristics of coal and rock after high temperature pre-damage. The results show that the thermal damage of coal and rock increases exponentially with the increase of temperature; the brittle-ductile failure characteristics of coal and rock appear at lower temperature(≤200℃) and the accelerated creep characteristics are not obvious; the brittle-brittle failure characteristics of coal and rock appear at higher temperature(＞200℃) and the accelerated creep characteristics are more obvious; the value of steady creep rate is between pre-damage …
Fractal Characteristics Of Pores And Microfractures Of Coals With Different Structure And Their Effect On Permeability, Ye Zhenni, Hou Enke, Duan Zhonghui, Wen Qiang, Huang Meitao, He Dan
Fractal Characteristics Of Pores And Microfractures Of Coals With Different Structure And Their Effect On Permeability, Ye Zhenni, Hou Enke, Duan Zhonghui, Wen Qiang, Huang Meitao, He Dan
Coal Geology & Exploration
The characteristics of pores and fractures in coal are the basis to study permeability. In this study, the micro-pores and fractures of coal samples with different structure taken from Guojiahe coal mine were analyzed using mercury injection experiment and scanning electron microscope. The micro-pores and fractures of intact coal and cataclastic coal samples were quantitatively analyzed by using Menger sponge and box-counting dimension. The comprehensive fractal dimension was calculated by pore volume weights. Based on fractal theory, the relationship between fractal dimension of coal samples and coal permeability have been discussed. The results show that brittle deformation adds complexity of …
A New Technique For The Measurement And Assessment Of Carotid Artery Wall Vibrations Using Ultrasound Rf Echoes, Samrand Sharifi, Hamid Behnam, Zahra Alizadeh Sani
A New Technique For The Measurement And Assessment Of Carotid Artery Wall Vibrations Using Ultrasound Rf Echoes, Samrand Sharifi, Hamid Behnam, Zahra Alizadeh Sani
Turkish Journal of Electrical Engineering and Computer Sciences
Atherosclerosis is known as the leading cause of heart attacks and brain strokes. One of the symptoms of this disease is the reduction of artery wall motion caused by age. This study presents a novel method to extract high frequency components of wall motion, wall vibrations, based on discrete wavelet transform. The fractal dimension, largest Lyapunov exponent, and spectral entropy are then analyzed to indicate the chaotic behavior in wall vibrations. Phase information from demodulated radiofrequency signals is extracted and the entropy of phase-difference is computed as a statistical measure for better characterization of the artery wall tissue. The results …
Analysis Of Clusterization Of C70 Molecules In Benzene Solutions Prepared By Various Methods, U. Makhmanov, O. Ismailova, A. Kokhkharov, S. Bakhramov
Analysis Of Clusterization Of C70 Molecules In Benzene Solutions Prepared By Various Methods, U. Makhmanov, O. Ismailova, A. Kokhkharov, S. Bakhramov
Bulletin of National University of Uzbekistan: Mathematics and Natural Sciences
Self-assembling features of molecules of C70 in benzene solution prepared in two various ways – equilibrium and non-equilibrium – has been investigated experimentally by method of high-resolution transmission electron microscopy. It was demonstrated, that the formation of densely packed monomolecular fullerene aggregates with a diameter of not more than 30 nm in solutions prepared by the equilibrium method (without the use of external mechanical influences on solution). In the case of solutions C70, which were prepared by the non-equilibrium method (stirring of solution of C70 by a mechanical rotator), large quasispherical aggregates of nanoporous structure with …
Simulation Of Fractal Growth On Metal Wire Electrode, Li-Feng Ding, Pei-Yuan Mao, Jun Cheng, Yu-Lan Niu, Yu-Hao Wen, Wei Chen
Simulation Of Fractal Growth On Metal Wire Electrode, Li-Feng Ding, Pei-Yuan Mao, Jun Cheng, Yu-Lan Niu, Yu-Hao Wen, Wei Chen
Journal of Electrochemistry
During processes of metal electrodepostion, there exist many complex morphological forms such as dendritic growing in the cathode deposited metal edge, which will seriously affect the quality of the electrodeposited product and current efficiency during machining. Investigations on dendritic crystal growing process and morphology could help controlling growth of electrolysis precipitate. In this work, Python and Matlab softwares were used, and the model of parallel electrode electrodeposition was established based on the diffusion-limited aggregation (DLA) model. By analyzing the law of fractal growth at different conditions of the particles number, probability, electrode spacing, the movement step length and orientation drift, …
Do Movement Patterns And Habitat Use Differ Between Optimal- And Suboptimal-Sized Northern Bobwhite Coveys?, Christopher K. Williams, Roger Applegate, Anthony R. Ives
Do Movement Patterns And Habitat Use Differ Between Optimal- And Suboptimal-Sized Northern Bobwhite Coveys?, Christopher K. Williams, Roger Applegate, Anthony R. Ives
National Quail Symposium Proceedings
The group size of social animals and spatial structure of the environment can affect group behavior and movement decisions. Our objective was to investigate movement patterns and habitat use of northern bobwhite coveys (Colinus virginianus) of different size. Using radiotelemetry, we continuously monitored covey group size, daily movement, and habitat use on 12 independent 259-ha study areas in eastern Kansas, USA, during the winters between 1997 and 2000. We used correlated random walk models and fractal dimension models to determine if covey size affected movement characteristics or habitat selection. Intermediate-sized coveys (9–12 individuals, close to optimal covey size) …
Color Texture Image Classification Based On Fractal Features And Extreme Learning Machine, Erkan Tanyildizi
Color Texture Image Classification Based On Fractal Features And Extreme Learning Machine, Erkan Tanyildizi
Turkish Journal of Electrical Engineering and Computer Sciences
Texture classification, especially color texture classification, is considered a significant step in segmentation and object classification. The property of color and texture is important for characterizing objects in natural scenes. Fractal dimension (FD) has many applications in the field of image compression and image segmentation. A series of FD features, such as mean, standard deviation, lacunarity, kurtosis, skewness, entropy, inverse difference moment, contrast, energy, dissimilarity, homogeneity, and maximum probability, are investigated for obtaining the maximum discrimination. In this manuscript, a methodology is proposed that is based on FD and an extreme learning machine for color texture classification. Performance of the …
Formation Of Copper Microcrystals On Porous Silicon Films, Lan-Li Chen, Fu-Fang Zhou, Bao-Gai Zhai, Yuan-Ming Huang
Formation Of Copper Microcrystals On Porous Silicon Films, Lan-Li Chen, Fu-Fang Zhou, Bao-Gai Zhai, Yuan-Ming Huang
Journal of Electrochemistry
Microcrystals of metallic copper were electrochemically deposited onto the surface of porous silicon films in the aqueous electrolyte of copper(II) chloride.The microstructures of electrochemically deposited copper microcrystals on the porous silicon films were characterized by using scanning electron microscopy.The results have demonstrated that both center-hollowed and center-solid equilateral triangles in the sizes of several micrometers can be formed on the smooth bed of copper microcrystals.As the deposition duration increased from 0 to 28 hours,the fractal dimensions of the porous silicon was decreased from 2.608 to 2.252,suggesting that the electrochemical deposition can smooth the rough surface of porous silicon films.Compared to …