The size distribution of the broken top coal blocks is an important factor,affecting the recovery ratio and the efficiency of drawing top coal in longwall top coal caving(LTCC)mining panel.The standard deviation of to...The size distribution of the broken top coal blocks is an important factor,affecting the recovery ratio and the efficiency of drawing top coal in longwall top coal caving(LTCC)mining panel.The standard deviation of top coal block size(dt)is one of the main parameters to reflect the size distribution of top coal.To find the effect of dt on the caving mechanism,this study simulates experiments with 9 different dt by using discrete element software PFC.The dt is divided into two stages:uniform distribution stage(UDS)whose dt is less than 0.1(Schemes 1–5),and nonuniform distribution stage(NDS)whose dt is more than 0.1(Schemes 6–9).This research mainly investigates the variation of recovery ratio,drawing body shape,boundary of top coal,and contact force between particles in the two stages,respectively.The results showed that with the increasing dt,the recovery ratio of the panel increases first and then decreases in UDS.It is the largest in Scheme 3,which mainly increases the drawing volume at the side of starting drawing end.However,the recovery ratio decreases first and then increases quickly in NDS,and it is the largest in Scheme 9,where the drawing volume at the side of finishing drawing end are relatively higher.In UDS,the major size of top coal is basically medium,while in NDS,the size varies from medium to small,and then to large,with a distinct difference in shape and volume of the drawing body.When the major size of top coal is medium and small,the cross-section width of the initial boundary of top coal at each height is relatively small.Conversely,when the top coal size is large,the initial boundary of top coal has a larger opening range,the rotating angle of lower boundary is relatively small in the normal drawing stage,which is conducive to the development of drawing body and reduces the residual top coal,and the maximum particle velocity and the particles movement angle are both larger.This study lays a foundation for the prediction of recovery ratio,and suggests that the uniform top coal is more manageable and has a larger recovery ratio.展开更多
As an explosion control measure, rock dusting has been used in underground coal mines in many major coal producing countries with different standards. The effectiveness of the rock dust in reducing explosion intensity...As an explosion control measure, rock dusting has been used in underground coal mines in many major coal producing countries with different standards. The effectiveness of the rock dust in reducing explosion intensity has been proven by historic events and laboratory experiments. The main functions of rock dust in controlling mine explosions (i.e., isolator, physical heat sink and chemical energy absorber) have been quantitatively studied and results are presented in this paper.展开更多
Based on catastrophe theory,we used the catastrophe progression method to predict the risk of coal and gas outbursts in coal mines.According to the major factors affecting coal and gas outbursts,we built a comprehensi...Based on catastrophe theory,we used the catastrophe progression method to predict the risk of coal and gas outbursts in coal mines.According to the major factors affecting coal and gas outbursts,we built a comprehensive evaluation index system and a coal and gas outburst prediction model.In addition,we performed a standard transformation for each index system;based on the degree the various indices affect the risk of an outburst,to make the data dimensionless.Based on the outburst data from eight mines,we determined catastrophe progression values and verified these values.The results show that:1) converting multi-dimensional problems into one-dimensional problems using this catastrophe progression method can simplify the steps of predicting coal and gas outbursts;2) when pre-determined catastrophe progression values are used to predict coal and gas outbursts,the predicting accuracy rate can be as high as 87.5%;3) the various coal mines have different factors inducing outbursts with varying importance of these factors and 4) the catastrophe progression values,calculated based on these factors,can be used effectively to predict the risk of outbursts in coal mines.展开更多
Laser-induced breakdown spectroscopy was employed to determine the inorganic elements in coal. To improve the measurement's accuracy and precision, a new internal standardization scheme, which we named changed intern...Laser-induced breakdown spectroscopy was employed to determine the inorganic elements in coal. To improve the measurement's accuracy and precision, a new internal standardization scheme, which we named changed internal standardization, was compared with the traditional internal standardization and no internal standardization for the analysis of inorganic elements. The new internal standardization scheme used the atomic line of carbon at 247.86 nm and the molecular band of CN at 388.34 nm and C2 at 516.32 nm to normalize the lines of inorganic elements that were distributed in the same spectral channel. The performance of the utilization of the new internal standardization scheme was evaluated using a set of coal samples, including twenty calibration samples and five validation samples. The results show that the coefficients of determination R2 and the slope of calibration models coupled with changed internal standard- ization are better than that of the calibration models coupled with fixed internal standardization and no internal standardization. Moreover, the measurement accuracy and reproducibility of changed internal standardization for the analysis of five validation samples also yielded further improvement. The results that we obtained suggest that changed internal standardization could compensate for the matrix effects, as well as the influence of the difference in the spectral response of the light collection system.展开更多
ETIOLOGICAL TERMSIn traditional Chinese medicine, etiology is commonly called "cause of disease". The various factors that may cause disease are called "pathogenic factors". In the past they were c...ETIOLOGICAL TERMSIn traditional Chinese medicine, etiology is commonly called "cause of disease". The various factors that may cause disease are called "pathogenic factors". In the past they were classified into three categories: "exogenous factors", "endogenous factors", and "non-exo-endogenous factors". In the modern textbooks this tri-causal hypothesis is not so widely used, while a new classification has been developed.展开更多
Via multi-dimensional gas chromatography, configured with parallel dual-channel, double detectors, valves switching and back flushing, rapid analysis of the gas compositions consisting of C1-C5 hydrocarbons and perman...Via multi-dimensional gas chromatography, configured with parallel dual-channel, double detectors, valves switching and back flushing, rapid analysis of the gas compositions consisting of C1-C5 hydrocarbons and permanent gases, such as CO2, H2S, H2, and CO, for direct coal liquefaction has been realized. With four packed chromatographic columns, which are Hayesep-Q pre-column, Hayesep-Q column, molecular sieve 5A column and one PLOT A1203 S capillary column, the gas compositions for direct coal liquefaction are analyzed qualitatively and quantitatively by the external standard method. The determination method has such advantages as excellent separation, simple operation, rapid analysis and accurate results.展开更多
Blood in Western medicine and血〔xue〕inTCM refer to the same substance,but some writ-ers insisted the use of xue or hsueh for TCM be-cause the latter’s knowledge about blood is differ-
Literary terms are the crystallization of Chinese ideology and wisdom. Translation and communication function as an important link in the construction of the discourse system with Chinese characteristics. Standardized...Literary terms are the crystallization of Chinese ideology and wisdom. Translation and communication function as an important link in the construction of the discourse system with Chinese characteristics. Standardized translation of literary terms is an important way to help the world understand China and promote international communication of Chinese culture, which is conducive to the inheritance and interpretation of fine traditional Chinese culture. From the perspective of the "going global" strategy of Chinese culture in the new era, and the existing asymmetry of English translation of Chinese literary terms in international cultural communication, we analyzed the divergence, variation and imposed interpretation of the translations of Chinese literary terms and put forward some suggestions for their standardization. We believe that the translation of Chinese literary terms should adhere to the principle of "localization" in cultural communication and focus on the transmission of Chinese cultural connotation to correct the imposed interpretations of Chinese literature in the West. Standardizing the translations of literary terms will facilitate the communication of "Chinese knowledge" to the world. The paper is expected to provide reference for research on construction and enhancement of discourse system for global communication with Chinese characteristics.展开更多
Standardization of translation of traditional Chinese medicine(TCM) terms has been the focus of TCM translation for a long time; and it is the important force to enhance the steps of TCM internationalization. The stan...Standardization of translation of traditional Chinese medicine(TCM) terms has been the focus of TCM translation for a long time; and it is the important force to enhance the steps of TCM internationalization. The standardization of translation of TCM terms is also the key to promote the theoretical research of TCM translation and the international exchange and scientific research.展开更多
There is an urgent need to develop optimal solutions for deformation control of deep high‐stress roadways,one of the critical problems in underground engineering.The previously proposed four‐dimensional support(here...There is an urgent need to develop optimal solutions for deformation control of deep high‐stress roadways,one of the critical problems in underground engineering.The previously proposed four‐dimensional support(hereinafter 4D support),as a new support technology,can set the roadway surrounding rock under three‐dimensional pressure in the new balanced structure,and prevent instability of surrounding rock in underground engineering.However,the influence of roadway depth and creep deformation on the surrounding rock supported by 4D support is still unknown.This study investigated the influence of roadway depth and creep deformation time on the instability of surrounding rock by analyzing the energy development.The elastic strain energy was analyzed using the program redeveloped in FLAC3D.The numerical simulation results indicate that the combined support mode of 4D roof supports and conventional side supports is highly applicable to the stability control of surrounding rock with a roadway depth exceeding 520 m.With the increase of roadway depth,4D support can effectively restrain the area and depth of plastic deformation in the surrounding rock.Further,4D support limits the accumulation range and rate of elastic strain energy as the creep deformation time increases.4D support can effectively reduce the plastic deformation of roadway surrounding rock and maintain the stability for a long deformation period of 6 months.As confirmed by in situ monitoring results,4D support is more effective for the long‐term stability control of surrounding rock than conventional support.展开更多
Many countries have strict emission limits for nitrogen oxides(NO_(x));thus NO_(x) control systems are widely deployed.India has recently introduced NO_(x) emission limits,which require that pollution control technolo...Many countries have strict emission limits for nitrogen oxides(NO_(x));thus NO_(x) control systems are widely deployed.India has recently introduced NO_(x) emission limits,which require that pollution control technologies must be installed on most coal-fired plants.However,operational experience with NO_(x) control systems in India is limited to primary measures only.Additionally,Indian coals have a high level of inherent ash,which is also highly erosive and can influence the behaviour of some NO_(x) control systems and thus affect the selection process.Primary measures for NO_(x) control from coal-fired power plants include low NO_(x) burners(LNBs),overfire air systems(OFA),fuel reburning,flue gas recirculation,fuel biasing,low excess air and combustion optimization.Secondary NO_(x) control includes selective catalytic reduction,selective non-catalytic reduction and multi-pollutant control systems.Retrofit of primary measures(LNBs and OFA)in India has been recommended to take place during next-scheduled plant outages;for many plants this could occur by 2019.However,control strategies for individual plants will be needed to ascertain the appropriateness of installing post-combustion technologies or various combinations of NO_(x) control measures.Hence installation of secondary NO_(x) controls is not expected before test results from secondary controls on selected Indian power plants units are known.展开更多
基金supported by the National Key R&D Plan of China,China(Grant No.2018YFC0604501)the Natural Science Foundation of China,China(Grant Nos.51934008,51674264,51904305)the Research Fund of the State Key Laboratory of Coal Resources and Safe Mining,CUMT,China(Grant No.SKLCRSM19KF023).
文摘The size distribution of the broken top coal blocks is an important factor,affecting the recovery ratio and the efficiency of drawing top coal in longwall top coal caving(LTCC)mining panel.The standard deviation of top coal block size(dt)is one of the main parameters to reflect the size distribution of top coal.To find the effect of dt on the caving mechanism,this study simulates experiments with 9 different dt by using discrete element software PFC.The dt is divided into two stages:uniform distribution stage(UDS)whose dt is less than 0.1(Schemes 1–5),and nonuniform distribution stage(NDS)whose dt is more than 0.1(Schemes 6–9).This research mainly investigates the variation of recovery ratio,drawing body shape,boundary of top coal,and contact force between particles in the two stages,respectively.The results showed that with the increasing dt,the recovery ratio of the panel increases first and then decreases in UDS.It is the largest in Scheme 3,which mainly increases the drawing volume at the side of starting drawing end.However,the recovery ratio decreases first and then increases quickly in NDS,and it is the largest in Scheme 9,where the drawing volume at the side of finishing drawing end are relatively higher.In UDS,the major size of top coal is basically medium,while in NDS,the size varies from medium to small,and then to large,with a distinct difference in shape and volume of the drawing body.When the major size of top coal is medium and small,the cross-section width of the initial boundary of top coal at each height is relatively small.Conversely,when the top coal size is large,the initial boundary of top coal has a larger opening range,the rotating angle of lower boundary is relatively small in the normal drawing stage,which is conducive to the development of drawing body and reduces the residual top coal,and the maximum particle velocity and the particles movement angle are both larger.This study lays a foundation for the prediction of recovery ratio,and suggests that the uniform top coal is more manageable and has a larger recovery ratio.
文摘As an explosion control measure, rock dusting has been used in underground coal mines in many major coal producing countries with different standards. The effectiveness of the rock dust in reducing explosion intensity has been proven by historic events and laboratory experiments. The main functions of rock dust in controlling mine explosions (i.e., isolator, physical heat sink and chemical energy absorber) have been quantitatively studied and results are presented in this paper.
基金Projects 50574072, 50874089 and 50534049 supported by the National Natural Science Foundation of China08JK366 by the Special Scientific Foundation of Educational Committee of Shaanxi Province
文摘Based on catastrophe theory,we used the catastrophe progression method to predict the risk of coal and gas outbursts in coal mines.According to the major factors affecting coal and gas outbursts,we built a comprehensive evaluation index system and a coal and gas outburst prediction model.In addition,we performed a standard transformation for each index system;based on the degree the various indices affect the risk of an outburst,to make the data dimensionless.Based on the outburst data from eight mines,we determined catastrophe progression values and verified these values.The results show that:1) converting multi-dimensional problems into one-dimensional problems using this catastrophe progression method can simplify the steps of predicting coal and gas outbursts;2) when pre-determined catastrophe progression values are used to predict coal and gas outbursts,the predicting accuracy rate can be as high as 87.5%;3) the various coal mines have different factors inducing outbursts with varying importance of these factors and 4) the catastrophe progression values,calculated based on these factors,can be used effectively to predict the risk of outbursts in coal mines.
基金supported by Open Research Fund of State Key Laboratory of Pulsed Power Laser Technology of China(No.SKL2013KF03)National Natural Science Foundation of China(Nos.51206055,51476061)+3 种基金the Fundamental Research Funds for the Central Universities of China(No.2014ZZ0014)the New Star of Pearl River on Science and Technology of Guangzhou,China(No.2014J2200054)the Key Laboratory of Efficient and Clean Energy Utilization of Guangdong Higher Education Institutes of China(No.KLB10004)Guangdong Province Key Laboratory of Efficient and Clean Energy Utilization,China(No.2013A061401005)
文摘Laser-induced breakdown spectroscopy was employed to determine the inorganic elements in coal. To improve the measurement's accuracy and precision, a new internal standardization scheme, which we named changed internal standardization, was compared with the traditional internal standardization and no internal standardization for the analysis of inorganic elements. The new internal standardization scheme used the atomic line of carbon at 247.86 nm and the molecular band of CN at 388.34 nm and C2 at 516.32 nm to normalize the lines of inorganic elements that were distributed in the same spectral channel. The performance of the utilization of the new internal standardization scheme was evaluated using a set of coal samples, including twenty calibration samples and five validation samples. The results show that the coefficients of determination R2 and the slope of calibration models coupled with changed internal standard- ization are better than that of the calibration models coupled with fixed internal standardization and no internal standardization. Moreover, the measurement accuracy and reproducibility of changed internal standardization for the analysis of five validation samples also yielded further improvement. The results that we obtained suggest that changed internal standardization could compensate for the matrix effects, as well as the influence of the difference in the spectral response of the light collection system.
文摘ETIOLOGICAL TERMSIn traditional Chinese medicine, etiology is commonly called "cause of disease". The various factors that may cause disease are called "pathogenic factors". In the past they were classified into three categories: "exogenous factors", "endogenous factors", and "non-exo-endogenous factors". In the modern textbooks this tri-causal hypothesis is not so widely used, while a new classification has been developed.
文摘Via multi-dimensional gas chromatography, configured with parallel dual-channel, double detectors, valves switching and back flushing, rapid analysis of the gas compositions consisting of C1-C5 hydrocarbons and permanent gases, such as CO2, H2S, H2, and CO, for direct coal liquefaction has been realized. With four packed chromatographic columns, which are Hayesep-Q pre-column, Hayesep-Q column, molecular sieve 5A column and one PLOT A1203 S capillary column, the gas compositions for direct coal liquefaction are analyzed qualitatively and quantitatively by the external standard method. The determination method has such advantages as excellent separation, simple operation, rapid analysis and accurate results.
文摘Blood in Western medicine and血〔xue〕inTCM refer to the same substance,but some writ-ers insisted the use of xue or hsueh for TCM be-cause the latter’s knowledge about blood is differ-
基金funded by the National Social Science Fund of China “Research on Henry H. Remak’s Thoughts in Comparative Literature”(20FWWB018)the research project of Translators Association of Sichuan “On the Translation of Chinese Literary Terms from the Perspective of International Communication”(YX2020011)。
文摘Literary terms are the crystallization of Chinese ideology and wisdom. Translation and communication function as an important link in the construction of the discourse system with Chinese characteristics. Standardized translation of literary terms is an important way to help the world understand China and promote international communication of Chinese culture, which is conducive to the inheritance and interpretation of fine traditional Chinese culture. From the perspective of the "going global" strategy of Chinese culture in the new era, and the existing asymmetry of English translation of Chinese literary terms in international cultural communication, we analyzed the divergence, variation and imposed interpretation of the translations of Chinese literary terms and put forward some suggestions for their standardization. We believe that the translation of Chinese literary terms should adhere to the principle of "localization" in cultural communication and focus on the transmission of Chinese cultural connotation to correct the imposed interpretations of Chinese literature in the West. Standardizing the translations of literary terms will facilitate the communication of "Chinese knowledge" to the world. The paper is expected to provide reference for research on construction and enhancement of discourse system for global communication with Chinese characteristics.
文摘Standardization of translation of traditional Chinese medicine(TCM) terms has been the focus of TCM translation for a long time; and it is the important force to enhance the steps of TCM internationalization. The standardization of translation of TCM terms is also the key to promote the theoretical research of TCM translation and the international exchange and scientific research.
基金support from the National Key Research and Development Program of China(Nos.2023YFC2907300 and 2019YFE0118500)the National Natural Science Foundation of China(Nos.U22A20598 and 52104107)the Natural Science Foundation of Jiangsu Province(No.BK20200634).
文摘There is an urgent need to develop optimal solutions for deformation control of deep high‐stress roadways,one of the critical problems in underground engineering.The previously proposed four‐dimensional support(hereinafter 4D support),as a new support technology,can set the roadway surrounding rock under three‐dimensional pressure in the new balanced structure,and prevent instability of surrounding rock in underground engineering.However,the influence of roadway depth and creep deformation on the surrounding rock supported by 4D support is still unknown.This study investigated the influence of roadway depth and creep deformation time on the instability of surrounding rock by analyzing the energy development.The elastic strain energy was analyzed using the program redeveloped in FLAC3D.The numerical simulation results indicate that the combined support mode of 4D roof supports and conventional side supports is highly applicable to the stability control of surrounding rock with a roadway depth exceeding 520 m.With the increase of roadway depth,4D support can effectively restrain the area and depth of plastic deformation in the surrounding rock.Further,4D support limits the accumulation range and rate of elastic strain energy as the creep deformation time increases.4D support can effectively reduce the plastic deformation of roadway surrounding rock and maintain the stability for a long deformation period of 6 months.As confirmed by in situ monitoring results,4D support is more effective for the long‐term stability control of surrounding rock than conventional support.
文摘Many countries have strict emission limits for nitrogen oxides(NO_(x));thus NO_(x) control systems are widely deployed.India has recently introduced NO_(x) emission limits,which require that pollution control technologies must be installed on most coal-fired plants.However,operational experience with NO_(x) control systems in India is limited to primary measures only.Additionally,Indian coals have a high level of inherent ash,which is also highly erosive and can influence the behaviour of some NO_(x) control systems and thus affect the selection process.Primary measures for NO_(x) control from coal-fired power plants include low NO_(x) burners(LNBs),overfire air systems(OFA),fuel reburning,flue gas recirculation,fuel biasing,low excess air and combustion optimization.Secondary NO_(x) control includes selective catalytic reduction,selective non-catalytic reduction and multi-pollutant control systems.Retrofit of primary measures(LNBs and OFA)in India has been recommended to take place during next-scheduled plant outages;for many plants this could occur by 2019.However,control strategies for individual plants will be needed to ascertain the appropriateness of installing post-combustion technologies or various combinations of NO_(x) control measures.Hence installation of secondary NO_(x) controls is not expected before test results from secondary controls on selected Indian power plants units are known.