Deep mining is imperative,and the consequent coal and gas outburst disasters triggered during coal uncovering are becoming increasingly severe.Therefore,this study investigated the mechanical mechanisms of outburst in...Deep mining is imperative,and the consequent coal and gas outburst disasters triggered during coal uncovering are becoming increasingly severe.Therefore,this study investigated the mechanical mechanisms of outburst instability from three dimensions:experiment,numerical simulation,and field application.Based on physical simulation tests with different outburst pore diameter,it was found that the gas pressure relief rate,gas emission volume,and outburst dynamic phenomena increase with outburst pore diameter.The migration patterns of the gas-solid two-phase flow evolved over time approximately into suspension flow,plug flow,dune flow,and stratified flow.The dominant influence of gas-driven tensile failure was amplified by uncovering coal area.The employment of the“fluid-solid-damage”coupling model revealed that coal damage,gas emission volume,deflection angle of outburst hole,roof displacement,maximum horizontal tensile stress,the horizontal tensile stress zone,the peak seepage force,and the damage zone all increased with uncovering coal areas.At the gas pressure of 0.74 MPa,when the uncovering coal areas were 3.189,4.754 and 6.225 m,the total gas emission volumes were 4.72×10^(-4),16.83×10^(-4),and 17.67 m^(2)/s,deflection angles of outburst hole were 150.79°,152.89°and 158.66°,the maximum roof displacements were 0.044,0.046,and 0.325 m,and the peak seepage force were 0.85,1.27,and 1.46 MPa/m,respectively.The regions of coal failure calculated by tensile failure criterion largely coincided with those calculated by the mixed failure criterion,far greater than those calculated by the shear failure criterion.As the increase of uncovering coal area,tensile weights of 80.72%,89.78%,and 93.01%,respectively.Comparisons with field outburst cases showed that both gas emission volume and outburst hole deflection angle reflected the tensile failure of coal.The mechanical instability process of outbursts under the influence of uncovering coal area and gas pressure was analyzed,developing the progressive cyclical method of coal uncovering,which provided a novel approach for the achievement of safe coal mining.展开更多
To study the law of gas dilatation energy release of rock cross-cut coal uncovering face, according to the analysis of the physical parameters distribution features of coal and rock mass in front of crosscut face,the ...To study the law of gas dilatation energy release of rock cross-cut coal uncovering face, according to the analysis of the physical parameters distribution features of coal and rock mass in front of crosscut face,the equations of elastic potential of coal and gas dilatation energy theory were set up to process a contrast calculation of the sizes of two kinds of energy. The results show that gas dilatation energy is the uppermost energy source causing outburst occurrence. Furthermore, the mathematical model of spherical flow field gas dilatation energy release was established and MATLAB software was applied to make a numerical calculation analysis on the law of gas dilatation energy release. The results indicate that the gas dilatation energy is closely related to gas parameters and its energy index does reflect the possibility of coal seam outburst.展开更多
Introduction Primary liver cancer, the second most common cause of cancer related death worldwide, presents ethnic, etiological, sex, and geographical diversity2 （Figure 1A）. At the histological level, liver cancer ...Introduction Primary liver cancer, the second most common cause of cancer related death worldwide, presents ethnic, etiological, sex, and geographical diversity2 （Figure 1A）. At the histological level, liver cancer includes two major types： hepatocellular carcinoma （HCC, about 80%） and cholangiocarcinoma （CCA, about 15%）. Many etiological factors contribute to HCC development, such as hepatitis B virus （HBV）, hepatitis C virus （HCV）, aflatoxin B1 （AFB1）, alcohol, and metabolic diseases3. By contrast, the major risk factors for CCA are liver flukes （Opisthorchis viverrini and Clonorchis sinensis） and primary sclerosing cholangitis4,展开更多
As mines become deeper,the potential for coal and gas outbursts in deep rock cross-cut coal uncovering is enhanced.The outburst precursors are unclear,which restricts the effectiveness and reliability of warning syste...As mines become deeper,the potential for coal and gas outbursts in deep rock cross-cut coal uncovering is enhanced.The outburst precursors are unclear,which restricts the effectiveness and reliability of warning systems.To reveal the evolution characteristics of coal and gas outburst precursor information in deep rock cross-cut coal uncovering,briquette specimens are constructed and experiments are conducted using a self-developed true triaxial outburst test system.Using acoustic emission monitoring technology,the dynamic failure of coal is monitored,and variations in the root mean square(RMS)of the acoustic emissions allow the effective cracking time and effective cracking gas pressure to be defined.These characteristics are obviously different in deep and shallow coal.The characteristic parameters of gas outburst exhibit stepwise variations at different depths.The RMS and cumulative RMS have stepped failure characteristics with respect to changes in gas pressure.The characteristic parameters of coal failure are negatively correlated with the average in-situ stress and effective stress,but positively correlated with the lateral pressure coefficient of in-situ stress and the critical gas pressure.The transition characteristics are highly sensitive in all cases.The critical depth between deep and shallow coal and gas outbursts is 1700 m.The expansion multiple of acoustic emission intensity from the microfracture stage to the sharp-fracture stage of coal is defined as the outburst risk index,N1.For depths of 1100–1700 m,N1≥7 denotes a higher risk of outburst,whereas at depths of 1700–2500 m,N1≥3 indicates enhanced risk.展开更多
EDITOR'S NOTE: Since May 2004, the people's procuratorates in China have concentrated their efforts on uncovering cases of encroaching upon human rights by government functionaries by abusing their power. The ...EDITOR'S NOTE: Since May 2004, the people's procuratorates in China have concentrated their efforts on uncovering cases of encroaching upon human rights by government functionaries by abusing their power. The move has aroused extensive attention. On this, our staff reporter interviewed Deputy Chief Procurator Wang Zhenchuan, who is in charge of the campaign against human rights violations.展开更多
With the long-term support by the National Natural Science Foundation of China,Ministry of Agriculture,and Science and Technology Department of Zhejiang Province,the research team led by Prof.Zhang Mingfang(张明方)at ...With the long-term support by the National Natural Science Foundation of China,Ministry of Agriculture,and Science and Technology Department of Zhejiang Province,the research team led by Prof.Zhang Mingfang(张明方)at Zhejiang University,assembled an allopolyploid B.juncea genome and uncovered differential homoeolog gene expression influencing selection,which was published in Nature展开更多
Tsinghua University studies reveal secrets from ancient bamboo texts China’s prestigious Tsinghua University recently released preliminary results of research on a rare collection of
Dr Emily Thompson decided it was time to set sail on her first major maritime research expedition.She had always been fascinated by the mysteries of the ocean and wanted to uncover the secrets hidden beneath the waves...Dr Emily Thompson decided it was time to set sail on her first major maritime research expedition.She had always been fascinated by the mysteries of the ocean and wanted to uncover the secrets hidden beneath the waves.Her team boarded the research vessel early in the morning,excited at the adventure that awaited them.展开更多
基金supported by the National Natural Science Foundation of China(Nos.52274242 and 51904293)the National Key R&D Program of China(No.2022YFC3004701)+2 种基金the Fundamental Research Funds for the Central Universities(No.2025QN1030)the Youth Science and Technology Talent Support Project of Jiangsu Province(No.JSTJ-2024-063)the Special Fund for Science and Technology of Jiangsu Province(No.BM2022013)。
文摘Deep mining is imperative,and the consequent coal and gas outburst disasters triggered during coal uncovering are becoming increasingly severe.Therefore,this study investigated the mechanical mechanisms of outburst instability from three dimensions:experiment,numerical simulation,and field application.Based on physical simulation tests with different outburst pore diameter,it was found that the gas pressure relief rate,gas emission volume,and outburst dynamic phenomena increase with outburst pore diameter.The migration patterns of the gas-solid two-phase flow evolved over time approximately into suspension flow,plug flow,dune flow,and stratified flow.The dominant influence of gas-driven tensile failure was amplified by uncovering coal area.The employment of the“fluid-solid-damage”coupling model revealed that coal damage,gas emission volume,deflection angle of outburst hole,roof displacement,maximum horizontal tensile stress,the horizontal tensile stress zone,the peak seepage force,and the damage zone all increased with uncovering coal areas.At the gas pressure of 0.74 MPa,when the uncovering coal areas were 3.189,4.754 and 6.225 m,the total gas emission volumes were 4.72×10^(-4),16.83×10^(-4),and 17.67 m^(2)/s,deflection angles of outburst hole were 150.79°,152.89°and 158.66°,the maximum roof displacements were 0.044,0.046,and 0.325 m,and the peak seepage force were 0.85,1.27,and 1.46 MPa/m,respectively.The regions of coal failure calculated by tensile failure criterion largely coincided with those calculated by the mixed failure criterion,far greater than those calculated by the shear failure criterion.As the increase of uncovering coal area,tensile weights of 80.72%,89.78%,and 93.01%,respectively.Comparisons with field outburst cases showed that both gas emission volume and outburst hole deflection angle reflected the tensile failure of coal.The mechanical instability process of outbursts under the influence of uncovering coal area and gas pressure was analyzed,developing the progressive cyclical method of coal uncovering,which provided a novel approach for the achievement of safe coal mining.
文摘To study the law of gas dilatation energy release of rock cross-cut coal uncovering face, according to the analysis of the physical parameters distribution features of coal and rock mass in front of crosscut face,the equations of elastic potential of coal and gas dilatation energy theory were set up to process a contrast calculation of the sizes of two kinds of energy. The results show that gas dilatation energy is the uppermost energy source causing outburst occurrence. Furthermore, the mathematical model of spherical flow field gas dilatation energy release was established and MATLAB software was applied to make a numerical calculation analysis on the law of gas dilatation energy release. The results indicate that the gas dilatation energy is closely related to gas parameters and its energy index does reflect the possibility of coal seam outburst.
基金supported,in part,by the Precision Medical Research Program from Ministry of Science and Technology of China(Grant No.YL 2017YFC0908400)National Science and Technology Major Project for Infectious Disease and Funding(Grant No.YL 17-163-12-ZT-005-095-01)+2 种基金Science and Technology Commission in Ministry of National Defense of China(Grant No.YL 17-163-12-ZT-005-095-01)Xinwei Wang was supported by the intramural research program of the Center for Cancer Research,National Cancer Institute of the United StatesJunfang Ji was supported by the Thousand Young Talents Plan of China,National Natural Science Foundation of China(Grant No.81672905)
文摘Introduction Primary liver cancer, the second most common cause of cancer related death worldwide, presents ethnic, etiological, sex, and geographical diversity2 （Figure 1A）. At the histological level, liver cancer includes two major types： hepatocellular carcinoma （HCC, about 80%） and cholangiocarcinoma （CCA, about 15%）. Many etiological factors contribute to HCC development, such as hepatitis B virus （HBV）, hepatitis C virus （HCV）, aflatoxin B1 （AFB1）, alcohol, and metabolic diseases3. By contrast, the major risk factors for CCA are liver flukes （Opisthorchis viverrini and Clonorchis sinensis） and primary sclerosing cholangitis4,
基金This research was financially supported by the National Natural Science Foundation of China(51874165,51974148)Liaoning Xingliao Talent Program(XLYC1902106).
文摘As mines become deeper,the potential for coal and gas outbursts in deep rock cross-cut coal uncovering is enhanced.The outburst precursors are unclear,which restricts the effectiveness and reliability of warning systems.To reveal the evolution characteristics of coal and gas outburst precursor information in deep rock cross-cut coal uncovering,briquette specimens are constructed and experiments are conducted using a self-developed true triaxial outburst test system.Using acoustic emission monitoring technology,the dynamic failure of coal is monitored,and variations in the root mean square(RMS)of the acoustic emissions allow the effective cracking time and effective cracking gas pressure to be defined.These characteristics are obviously different in deep and shallow coal.The characteristic parameters of gas outburst exhibit stepwise variations at different depths.The RMS and cumulative RMS have stepped failure characteristics with respect to changes in gas pressure.The characteristic parameters of coal failure are negatively correlated with the average in-situ stress and effective stress,but positively correlated with the lateral pressure coefficient of in-situ stress and the critical gas pressure.The transition characteristics are highly sensitive in all cases.The critical depth between deep and shallow coal and gas outbursts is 1700 m.The expansion multiple of acoustic emission intensity from the microfracture stage to the sharp-fracture stage of coal is defined as the outburst risk index,N1.For depths of 1100–1700 m,N1≥7 denotes a higher risk of outburst,whereas at depths of 1700–2500 m,N1≥3 indicates enhanced risk.
文摘EDITOR'S NOTE: Since May 2004, the people's procuratorates in China have concentrated their efforts on uncovering cases of encroaching upon human rights by government functionaries by abusing their power. The move has aroused extensive attention. On this, our staff reporter interviewed Deputy Chief Procurator Wang Zhenchuan, who is in charge of the campaign against human rights violations.
文摘With the long-term support by the National Natural Science Foundation of China,Ministry of Agriculture,and Science and Technology Department of Zhejiang Province,the research team led by Prof.Zhang Mingfang(张明方)at Zhejiang University,assembled an allopolyploid B.juncea genome and uncovered differential homoeolog gene expression influencing selection,which was published in Nature
文摘Tsinghua University studies reveal secrets from ancient bamboo texts China’s prestigious Tsinghua University recently released preliminary results of research on a rare collection of
文摘Dr Emily Thompson decided it was time to set sail on her first major maritime research expedition.She had always been fascinated by the mysteries of the ocean and wanted to uncover the secrets hidden beneath the waves.Her team boarded the research vessel early in the morning,excited at the adventure that awaited them.
