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160 results on '"He, Xueqiu"'

153. Coal-rock dynamic disaster assessment model based on electromagnetic emission and least-squares support vector machine

Author

He Xueqiu, Chen Wenxue, and Nie Baisheng

Subjects
Engineering, Operations research, business.industry, Coal mining, Sample (statistics), Disaster assessment, Management Science and Operations Research, Electromagnetic emission, computer.software_genre, Support vector machine, Least squares support vector machine, Coal, Data mining, Statistics, Probability and Uncertainty, Business and International Management, Multiple classification, business, computer
Abstract

A new non-linear assessment model for coal-rock dynamic disasters is reported in this paper. Coal-rock dynamic disaster assessment parameters are difficult to obtain because assessment samples are usually rare. The least-squares, a non-linear and few sample assessment methods can satisfy requirements on the availability of few samples. Based on the electromagnetic emission (EME) testing results and multiple classification theory of support vector machine, an EME least-squares support vector machine assessment model is built. In a case study, the results show that the EME least-squares support vector machine assessment model for coal and gas outburst is reliable and accurate, and can be applied to the assessment of coal-rock dynamic disasters in coal mines.

Published
2010

154. Basic Characteristics of Work Safety in China.

Author

He, Xueqiu and Song, Li

Abstract

Abstract: This paper describes current work safety status in China and analyzes main features of it from socioeconomic viewpoint. Rapid economic speed has certain negative effect on work safety, much high proportion of industry such as mining, manufacturing and construction in national economy reflects high social risks, and low level of industrial workers, especially peasant workers increases human error risks and make it urgent and necessary to build a scientific and suitable education system to enhance work safety training. Different regions show obvious difference both in work safety and socioeconomic development, regional fatality rate in industrial accidents would decline with rise of regional economic income. Forceful work safety policies and measures made by the Government since 2002 have put the tendency toward higher frequency of accidents under effective control. [Copyright &y& Elsevier]

Published
2012
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155. Study on mechanical property and electromagnetic emission during the fracture process of combined coal-rock

Author

Zhu Chen-wei, He Xueqiu, and Nie Baisheng

Subjects
Mechanical property, Materials science, electromagnetic emission, business.industry, technology, industry, and agriculture, Earth and Planetary Sciences(all), Uniaxial compression, General Medicine, Electromagnetic emission, respiratory system, complex mixtures, respiratory tract diseases, mechanical property, otorhinolaryngologic diseases, Geotechnical engineering, Coal, Fracture process, business, combined coal-rock
Abstract

The mechanical characteristics and electromagnetic emission rules during the uniaxial compression of the combined coal-rock were investigated in laboratory and its mechanical property was analyzed; the relation between mechanical characteristics and electromagnetic emission of the combined coal-rock was discussed. The results show that the combined coal-rock strength under the uniaxial compression is obviously different from that of single coal or rock and the fracture process of the combined coal-rock is gradual, accompanied by electromagnetic emission. This research has an important significance to further understanding of the mechanism and forecasting method of coal or rock dynamical disasters in theory and practice.

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156. Effect of meshy obstacle on methane gas explosion

Author

Wang Huia, Luo Geng, He Xueqiu, and Yang Yi

Subjects
Premixed flame, turbulent flow, fractal dimension, Materials science, Laminar flame speed, Turbulence, Diffusion flame, Environmental engineering, Poison control, flame propagation, General Medicine, Mechanics, Flame speed, Combustion, gas explosion, Schlieren, obstacle, Engineering(all)
Abstract

In this paper the effect of meshy obstacle on methane gas explosion is experimented by high speed schlieren technique, the images of explosion flame crossing obstacle is gained and flame propagation velocity and temperature is measured. The experimental results showed that meshy obstacle disturbed unburned gas and enhanced the camber of flame front surface and the turbulent intensity of flame inner flow field, combustion reaction is more violent and fractal dimension of flame front surface and flame inner flow field increase too.

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157. Different Gas Explosion Mechanisms and Explosion Suppression Techniques

Author

He Xueqiu, Liu Xinna, Nie Baisheng, Zhao Caihong, Dai Linchao, Li Hailong, Li Qian, Wang Chao, and Zhang Ruming

Subjects
Waste management, business.industry, Chemistry, deflagration, detonation, Coal mining, Detonation, porous medium, General Medicine, Combustion, Mining engineering, water barriers, Gas explosion, gas explosions, Deflagration, business, Engineering(all)
Abstract

Gas explosions are characterized principally in terms of two types according to the mechanism of combustion: deflagrations and detonations; detonations can be further subdivided into unstable detonations and stable detonations. All these three kinds of explosions are possible in confined underground coal mine roadways, so corresponding explosion suppression techniques shall be available. The effectiveness of water barriers commonly used in today's coal mines is in doubt in views of catastrophic gas explosions occurring from time to time. In this paper, different gas explosion mechanisms are theoretically investigated; the adequacy of current explosion suppression measures is explored. Along with the explosion suppression materials generally used in other process industries, their possible applications in coal mine roadways are discussed. It is concluded that porous medium is a promising material. If they are used with water barriers together, explosion accidents may be diminished to the minimum and production safety be guaranteed to the maximum.

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158. AFM characterization of surface mechanical and electrical properties of some common rocks

Author

Tian, Xianghui, He, Xueqiu, Song, Dazhao, Li, Zhenlei, Khan, Majid, Liu, Huifang, and Qiu, Liming

Abstract

The characterization of micro-surface mechanical and electrical properties of the natural rock materials remains inadequate, and their macroscopic performance can be better comprehended by investigating the surface properties. With this purpose, the present research focuses on characterizing the micro-surface morphology, Derjaguin-Muller-Toporov (DMT) modulus, adhesion, and potential of granite, shale, and limestone by employing the atomic force microscope (AFM) as a pioneer attempt. The results show that the micro-surface morphology of the rock fluctuates within hundreds of nanometers, among which the granite micro-surface is comparatively the smoothest, followed by limestone. The morphology of the shale is the roughest, indicating that the regional difference of shale micro-surface is dominant. The distribution of the adhesion on rock micro-surface is uneven; the average adhesion of eight measuring areas for shale is 23.93 nN, accounting for three times of granite and limestone, while the surface DMT modulus of shale is relatively lower than granite and limestone. It is inferred from the obtained results that higher surface adhesion is helpful to the gas adsorption of shale, and the lower surface DMT (elastic) modulus is useful to the formation of fractures and pores. Thus, these two are the micromechanical basis of shale gas adsorption. Additionally, introducing a method to reduce the surface adhesion will benefit the exploration of unconventional resources such as shale gas. The micro-surface of the three types of rocks all shows electricity, with average potential ranging from tens of millivolts to hundreds of millivolts. Besides, the micro-surface potential of the rocks are heterogeneous, and both positive and negative points can be found. The existence and uneven distribution of micro-surface potential provide a robust physical basis for the electromagnetic radiation generated by rock fracture under loading. This study offers a new method for revealing the adsorption characteristics of unconventional gas reservoir rocks and the electromagnetic radiation mechanism of the rock fracture.

Published
2021
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159. Research on electromagnetic radiation (EMR) waveform characteristics of coal failure process using Hilbert-Huang transform (HHT).

Author

Yin, Shan, Song, Dazhao, Li, Jie, He, Xueqiu, Qiu, Liming, Lou, Quan, Wei, Menghan, and Liu, Yang

Subjects
*ELECTROMAGNETIC radiation, *HILBERT-Huang transform, *COAL, *WAVELET transforms, *FOURIER transforms
Abstract

• HHT method can well process and analyze the EMR waveform signal of coal failure. • The EMR parameters extracted by HHT improve the identification of coal failure. • Compared with STFT and WT, HHT has more advantages in processing EMR waveform. Electromagnetic radiation (EMR) waveforms contain rich information on coal fracture law, which is of great value to the refined study of their characteristics. In this paper, the Hilbert-Huang transform (HHT) method is used to analyze and process EMR waveform of coal failure process. The results show that HHT method can adapt well to the nonstationary and nonlinear characteristics of EMR waveform. It adaptively decomposes EMR waveforms by empirical mode decomposition (EMD), extracts the intrinsic mode function (IMF) characteristics of EMR waveforms, and obtains the law of instantaneous energy changes of EMR waveforms. At the same time, EMR waveform energy is quantitatively expressed on the three-dimensional Hilbert energy spectrum (time–frequency-energy distribution), and the refined features of EMR waveform signal are effectively extracted. The instantaneous energy of EMR and the three-dimensional Hilbert energy spectrum processed by HHT method more easily describe the fracture law of coal body. Compared with conventional characteristic parameters, such as EMR amplitude and dominant frequency, the identification degree of the precursor characteristics of coal body instability is greatly improved. Among the short-term Fourier transform (STFT), wavelet transform (WT) and HHT nonstationary signal processing methods, HHT method has an improved adaptability and superiority and can reveal the characteristics of coal deformation and failure more carefully and accurately, which provides a new means for better using and improving EMR method to monitor coal instability and failure. [ABSTRACT FROM AUTHOR]

Published
2022
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160. Early-warning of rock burst in coal mine by low-frequency electromagnetic radiation.

Author

Qiu, Liming, Liu, Zhentang, Wang, Enyuan, He, Xueqiu, Feng, Junjun, and Li, Baolin

Subjects
*ROCK bursts, *ELECTROMAGNETIC radiation, *ROCK deformation, *ROCK concerts, *SEPARATION (Technology), *COAL mining accidents, *EMERGENCY management, *HORIZONTAL wells
Abstract

Rock burst is one of the major geological hazards in coal mines and is difficult to prevent. Faced with this problem, the low-frequency electromagnetic radiation (EMR) test experiments of coal and rock were conducted to explore the characteristics of low-frequency EMR (1 kHz) signals induced form fractures. The relation between EMR signals and paroxysmal fractures was analyzed theoretically. Time-series extraction method was put forward to represent coal and rock paroxysmal fractures. The research results showed that deformation and fracture of coal and rock is caused by the accumulation of paroxysmal and discrete fractures in the samples. The time series obtained by moving average method shows rather good correlation with interior coal rock fractures, which has more obvious precursory characteristics of coal rock instability and dynamic disasters. When the coal rocks are damaged under uniaxial compression, low-frequency EMR (1 kHz) signals are more sensitive to local fracture with more abundant precursor information than high-frequency EMR (500 kHz) signals. The paroxysmal and discrete low-frequency EMR (1 kHz) signal is quite sensitive to rock burst, and when the signals representing coal rock fractures show an increasing trend and the high signals last for some time, it can be regarded as the precursor of rock burst disaster in coal mine. The separation technology of EMR representing coal rock fractures provided the key scientific basis for the field monitoring and forewarning of EMR technology, and a new method to identify the precursor of dynamic disasters of coal and rock. • An effective method is proposed to analyze the discreteness and continuity of electromagnetic radiation sequence. • Compared with high-frequency EMR, the low-frequency EMR are more sensitive to fractures with richer precursor information. • The processed EMR signals have more obvious precursory features for rock burst in coal mine. [ABSTRACT FROM AUTHOR]

Published
2020
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