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16. Segmentation of micro-cracks in fractured coal based on convolutional neural network

Author

Zheng Jiangtao, Qi Zihao, Liu Jiacun, Ma Deming, and Jü Yang

Subjects
fractured coal, image segmentation of micro-cracks, convolutional neural network, deep learning, Engineering geology. Rock mechanics. Soil mechanics. Underground construction, TA703-712, Mining engineering. Metallurgy, TN1-997
Abstract

The extension, penetration and expansion of coal and rock fracture structure caused by deep mining are the key factors that cause coal and rock damage.Therefore, the accurate characterization of the fracture structure is one of the core elements for understanding the coal and rock failure mechanism and developing coal and gas green co-mining.In this study, the Waifu2x convolutional neural network model was used to process the fractured coal and rock CT images to obtain CT images with higher resolution.And put forward the "seven-step processing method of fissure coal and rock labeling", which improves the efficiency of labeling, and uses image enhancement technology to expand the training set, which meets the model's requirements for the quantity and quality of the training set.The trained U-Net convolutional neural network is used for image segmentation to extract the fracture information in the coal and rock.Through comparison, it is found that the fracture connectivity, opening and distribution obtained by this method are closer to the real CT images, and the four quantitative indicators of the extracted fractures are better than other extraction methods.This study can provide a research foundation for the physical and mechanical behavior and mechanism analysis of fractured coal.

Published
2022
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24. van der Waals ZnO/HfSn2N4Heterojunction with Exceptional Photoresponse for Photodetectors

Author

Shen, Yang, Zhao, Xiaoyu, Cui, Zhen, Qin, Ke, Ma, Deming, Cheng, Fengjiao, Yuan, Pei, Qi, Xiangfeng, and Li, Enling

Abstract

Two-dimensional van der Waals heterojunctions represent a promising avenue for a spectrum of optoelectronic endeavors. Nonetheless, their deployment has been somewhat constrained by the suboptimal efficiency of the photocurrent generated. In this article, a ZnO/HfSn2N4heterojunction is proposed to achieve high photoresponse efficiency. First-principles calculations are utilized to confirm that this heterojunction possesses thermal stability with a direct bandgap (1.36 eV). It exhibits a high light absorption coefficient and high carrier mobility (2.51 × 103cm2V–1s–1), and biaxial strain has a significant effect on the modulation of the band structure. As the tensile strain increases, the bandgap changes nonlinearly, transitioning from a type-II to a type-I heterojunction. When compressive strain increases, the bandgap decreases. Quantum transport simulations are employed to calculate the density of states and transmission spectrum of the ZnO/HfSn2N4model, verifying its excellent photoresponse (a photocurrent peak reaching 4.93 a02/photon and an extinction ratio peak of 75.1). It shows that the ZnO/HfSn2N4heterojunction is a potentially efficient photodetector.

Published
2024
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41. g-ZnO/Si9C15: a S-scheme heterojunction with high carrier mobility for photo-electro catalysis of water splitting.

Author

Shen, Yang, Yuan, Zhihao, Cui, Zhen, Ma, Deming, Yuan, Pei, Cheng, Fengjiao, Yang, Kunqi, Dong, Yanbo, and Li, Enling

Abstract

The g-ZnO/Si9C15 heterojunction is designed, and its stability, electronic properties and photo-electro catalytic properties, and the impact of biaxial strain on the electronic and photocatalytic properties are investigated. The g-ZnO/Si9C15 heterojunction has a staggered (type-II) band structure (band gap is 1.770 eV), following the S-scheme mechanism. A high electron mobility of 5.113 × 103 cm2 V−1 s−1 and hole mobility of 3.324 × 104 cm2 V−1 s−1 are obtained in the zigzag and armchair directions, respectively. Suitable oxidation and reduction potentials are obtained such that photocatalytic water decomposition can occur at pH = 0–14, and the corrected solar to hydrogen (STH) efficiency is up to 35.4%. The absorption of visible light is enhanced, and the power conversion efficiency (PCE) is 15.1%. The electro-catalytic hydrogen evolution reaction (HER) is more likely to occur at the Si9C15 interface with a low over-voltage of 0.190 V. Under biaxial strain, due to the controllable band structure, the corrected STH efficiency and PCE increase to 42.7% and 16.7%, respectively. The heterojunction shows potential value in the field of high-efficiency solar devices and catalytic materials for water splitting. [ABSTRACT FROM AUTHOR]

Published
2024
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