In coal mines,dynamic disasters such as rock bursts seriously threaten the safety of mining activities.Exploring the dynamic behaviors and disaster characteristics in the impact failure process of coal serves as the b...In coal mines,dynamic disasters such as rock bursts seriously threaten the safety of mining activities.Exploring the dynamic behaviors and disaster characteristics in the impact failure process of coal serves as the basis and prerequisite for monitoring and warning rock bursts.In this context,impact failure tests of coal were carried out under different axial static loads and impact velocities to analyze the dynamic behaviors and acoustic emission(AE)response characteristics of coal.The results show that the dynamic behaviors of coal under combined dynamic and static loads are significantly different from those under static loads,and the stress-strain curve displays double peaks without an obvious compaction stage.As the axial static load grows,the dynamic strength and peak strain both have a quadratic function with the axial static load.When the coal damage intensifies instantaneously,the AE count and energy parameters both witness pulse-like increases and reach their peak values.The damage effect of axial static loads on coal,though limited,has an extreme point.In contrast,the impact velocity can strengthen the response of AE signals and has linear function relationships with the peak values of AE count and energy.This plays a leading role in the damage to samples and sets a critical point for coal failure and fracture.Compared with the analysis results of stress and strain,the responses of AE signals are more accurate and reliable.Based on AE response characteristics,the damage evolution process of coal under the combined dynamic and static loads can be identified more accurately to reveal the moment corresponding to coal damage and the characteristics of coal failure.The research results are conducive to the further application of AE monitoring methods to early warning of rock burst disasters in coal mining sites.展开更多
This study aims to investigate mechanical properties and failure mechanisms of layered rock with rough joint surfaces under direct shear loading.Cubic layered samples with dimensions of 100 mm×100 mm×100 mm ...This study aims to investigate mechanical properties and failure mechanisms of layered rock with rough joint surfaces under direct shear loading.Cubic layered samples with dimensions of 100 mm×100 mm×100 mm were casted using rock-like materials,with anisotropic angle(α)and joint roughness coefficient(JRC)ranging from 15°to 75°and 2-20,respectively.The direct shear tests were conducted under the application of initial normal stress(σ_(n)) ranging from 1-4 MPa.The test results indicate significant differences in mechanical properties,acoustic emission(AE)responses,maximum principal strain fields,and ultimate failure modes of layered samples under different test conditions.The peak stress increases with the increasingαand achieves a maximum value atα=60°or 75°.As σ_(n) increases,the peak stress shows an increasing trend,with correlation coefficients R² ranging from 0.918 to 0.995 for the linear least squares fitting.As JRC increases from 2-4 to 18-20,the cohesion increases by 86.32%whenα=15°,while the cohesion decreases by 27.93%whenα=75°.The differences in roughness characteristics of shear failure surface induced byαresult in anisotropic post-peak AE responses,which is characterized by active AE signals whenαis small and quiet AE signals for a largeα.For a given JRC=6-8 andσ_(n)=1 MPa,asαincreases,the accumulative AE counts increase by 224.31%(αincreased from 15°to 60°),and then decrease by 14.68%(αincreased from 60°to 75°).The shear failure surface is formed along the weak interlayer whenα=15°and penetrates the layered matrix whenα=60°.Whenα=15°,as σ_(n) increases,the adjacent weak interlayer induces a change in the direction of tensile cracks propagation,resulting in a stepped pattern of cracks distribution.The increase in JRC intensifies roughness characteristics of shear failure surface for a smallα,however,it is not pronounced for a largeα.The findings will contribute to a better understanding of the mechanical responses and failure mechanisms of the layered rocks subjected to shear loads.展开更多
Carbon emissions embodied in international trade of China during 1997-2007 are accounted by input-output method based on Chinese input-output table and global trade analysis project database.It is revealed that carbon...Carbon emissions embodied in international trade of China during 1997-2007 are accounted by input-output method based on Chinese input-output table and global trade analysis project database.It is revealed that carbon emissions embodied in imports and exports both increased during 1997-2007,but carbon emissions embodied in exports are greater than those embodied in imports,China is a net export nation in embodied carbon.The net exports of embodied carbon account for about 10.82%of the total carbon emissions in 1997,dropped to 7.15%in 2002,increased to 13.13%in 2006,and slightly dropped to 12.64%in 2007.Low-end position of international industry division is an objective factor of being a net exporter of embodied carbon for China,and usage of a large amount of obsolete energy-using equipments wasted much energy and increased carbon emissions embodied in exports. Importers should take more responsibilities for carbon emissions embodied in trade,and China should take a certain responsibility for unreasonable energy dissipations too.展开更多
A 24-metal Cd_((II))-Sm_((III))nanocluster[Cd_(18)Sm_(6)L_(9)(OAc)_(3)_(6)](CSN)was constructed from a new flexible Schiff base ligand.It can be used as a probe to detect 2,6-dichloro-4-nitroaniline(DCN,LOD:0.67-0.75...A 24-metal Cd_((II))-Sm_((III))nanocluster[Cd_(18)Sm_(6)L_(9)(OAc)_(3)_(6)](CSN)was constructed from a new flexible Schiff base ligand.It can be used as a probe to detect 2,6-dichloro-4-nitroaniline(DCN,LOD:0.67-0.75μM),which is not influenced by the presence of other pesticides.The response behavior of CSN to DCN is expressed using a first-order equation 1/I_(475nm)+1/I_(645nm)+1/I_(945nm)=A[DCN]+B,and it is used to determine DCN concentrations in the extract of fruits.For example,for the concentration determination of DCN in carrot extract,the ranges of recovery and RSD are 96.11-103.50%and 0.95-4.12%,respectively.展开更多
A 1-D coordination polymer[Sm(HL)_(2)(NO_(3))]_(n)(1)was constructed using a new flexible Schiff base ligand that has a long-chain(CH_(2))10 backbone.The Schiff base ligand exhibits a linear coordination configuration...A 1-D coordination polymer[Sm(HL)_(2)(NO_(3))]_(n)(1)was constructed using a new flexible Schiff base ligand that has a long-chain(CH_(2))10 backbone.The Schiff base ligand exhibits a linear coordination configuration,resulting in the“zig-zag”structure of 1.Besides the ligand-centered emission,1 displays typical visible and NIR luminescence of Sm^(3+).Interestingly,1 shows dual-emissive response to metal ions,especially to Co^(2+)at the ppm level.展开更多
Smart materials,such as stimuli-responsive luminescence,have attracted much attentions due to their potential application in semiconductor filed.In this context,platinum complexes of(dfppy-DC)Pt(acac) and(dfppy-O-DC)P...Smart materials,such as stimuli-responsive luminescence,have attracted much attentions due to their potential application in semiconductor filed.In this context,platinum complexes of(dfppy-DC)Pt(acac) and(dfppy-O-DC)Pt(acac) were prepared and characterized,in which(2-(4',6'-difluorophenyl)pyridinato-N,C2')(2,4-pentanedionato-0,0)Pt(Ⅱ) was used as the planar emission core and 9-(4-(phenylsulfonyl)phenyl)-9 H-carbazole(DC) was regard as the bent pendent.Both platinum complexes showed bright emission in solution and solid state,concomitant with charming external-stimuli-responsive emission under mechanical grinding,organic solvent vapors and pressure.The change emission color spanned from yellow to near-infrared region.Using the platinum complexes as the dopant,solution processable organic light-emitting diodes(OLEDs) were fabricated and a maximum external quantum efficiency of ~18% was achieved,which is the highest value among the reported solution-processable OLEDs based on externalstimuli-responsive luminescence.This research demonstrated that platinum complex can show promising stimuli responsive emission via ingenious molecular design,indicating a novel way for developing the smart materials in semiconductor filed.展开更多
This article describes the development and implementations of a novel software platform that supports real-time, science-based policy making on air quality through a user-friendly interface. The software, RSM-VAT, use...This article describes the development and implementations of a novel software platform that supports real-time, science-based policy making on air quality through a user-friendly interface. The software, RSM-VAT, uses a response surface modeling（RSM） methodology and serves as a visualization and analysis tool（VAT） for three-dimensional air quality data obtained by atmospheric models. The software features a number of powerful and intuitive data visualization functions for illustrating the complex nonlinear relationship between emission reductions and air quality benefits. The case study of contiguous U.S.demonstrates that the enhanced RSM-VAT is capable of reproducing the air quality model results with Normalized Mean Bias 〈 2% and assisting in air quality policy making in near real time.展开更多
Inter-provincial carbon compensation is an important means for a country to realize regional environmental protection and achieve coordinated regional development and realize the carbon neutral goal.It is easier to re...Inter-provincial carbon compensation is an important means for a country to realize regional environmental protection and achieve coordinated regional development and realize the carbon neutral goal.It is easier to realize inter-provincial carbon compensation compared with the national level.Based on the multi-regional input-output model and the input-output data of 30 provinces in China,this study measured the carbon transfer in,carbon transfer out and net carbon transfer of each province,and based on the undesirable slacks-based measurement model under the common frontier,the provinces were given the shadow price of carbon emission in line with the situation of the local economic development,resource endowment,and industrial structure,and based on which,the amount of carbon compensation of each province was measured.The results show that:China's provinces and regions have a larger share of trade-implied carbon emissions;the net carbon transfer in areas mainly concentrated in the traditional energy provinces,which provide industrial products for other regions and undertake the transfer of carbon emissions,and become the main carbon compensation recipient areas;the net carbon transfer out is mainly concentrated in the economically developed and densely populated areas such as Beijing-Tianjin region and the eastern and southern coasts,which satisfy the end-consumption by purchasing a large number of industrial products and generate a large amount of carbon emissions.Transfer out;becoming the main carbon offset payment area.Based on the results of this study,it is proposed to improve the national provincial carbon offset mechanism and implement a differentiated and synergistic carbon emission reduction cooperation approach.The research program of this study can provide a reference for the development of inter-regional carbon offset programs.展开更多
基金Open Fund of State Key Laboratory of Coal Mine Disaster Dynamics and Control,Grant/Award Number:2011DA105287-FW202306Postgraduate Research&Practice Innovation Program of Jiangsu Province,Grant/Award Number:KYCX24_2925+4 种基金Fundamental Research Program of Xuzhou,Grant/Award Number:KC23017National Natural Science Foundation of China,Grant/Award Number:52104234Fundamental Research Funds for the Central Universities,Grant/Award Number:2024-10962National Science Foundation for Young Scientists of Jiangsu Province,Grant/Award Number:BK20200657Graduate Innovation Program of China University of Mining and Technology,Grant/Award Number:2024WLKXJ152。
文摘In coal mines,dynamic disasters such as rock bursts seriously threaten the safety of mining activities.Exploring the dynamic behaviors and disaster characteristics in the impact failure process of coal serves as the basis and prerequisite for monitoring and warning rock bursts.In this context,impact failure tests of coal were carried out under different axial static loads and impact velocities to analyze the dynamic behaviors and acoustic emission(AE)response characteristics of coal.The results show that the dynamic behaviors of coal under combined dynamic and static loads are significantly different from those under static loads,and the stress-strain curve displays double peaks without an obvious compaction stage.As the axial static load grows,the dynamic strength and peak strain both have a quadratic function with the axial static load.When the coal damage intensifies instantaneously,the AE count and energy parameters both witness pulse-like increases and reach their peak values.The damage effect of axial static loads on coal,though limited,has an extreme point.In contrast,the impact velocity can strengthen the response of AE signals and has linear function relationships with the peak values of AE count and energy.This plays a leading role in the damage to samples and sets a critical point for coal failure and fracture.Compared with the analysis results of stress and strain,the responses of AE signals are more accurate and reliable.Based on AE response characteristics,the damage evolution process of coal under the combined dynamic and static loads can be identified more accurately to reveal the moment corresponding to coal damage and the characteristics of coal failure.The research results are conducive to the further application of AE monitoring methods to early warning of rock burst disasters in coal mining sites.
基金financial support from the National Natural Science Foundation of China(Nos.52174092,51904290,52004272,52104125,42372328,and U23B2091)Natural Science Foundation of Jiangsu Province,China(Nos.BK20220157 and BK20240209)+3 种基金the Fundamental Research Funds for the Central Universities,China(No.2022YCPY0202)Xuzhou Science and Technology Project,China(Nos.KC21033 and KC22005)Yunlong Lake Laboratory of Deep Underground Science and Engineering Project,China(No.104023002)the Graduate Innovation Program of China University of Mining and Technology(No.2023WLTCRCZL052)。
文摘This study aims to investigate mechanical properties and failure mechanisms of layered rock with rough joint surfaces under direct shear loading.Cubic layered samples with dimensions of 100 mm×100 mm×100 mm were casted using rock-like materials,with anisotropic angle(α)and joint roughness coefficient(JRC)ranging from 15°to 75°and 2-20,respectively.The direct shear tests were conducted under the application of initial normal stress(σ_(n)) ranging from 1-4 MPa.The test results indicate significant differences in mechanical properties,acoustic emission(AE)responses,maximum principal strain fields,and ultimate failure modes of layered samples under different test conditions.The peak stress increases with the increasingαand achieves a maximum value atα=60°or 75°.As σ_(n) increases,the peak stress shows an increasing trend,with correlation coefficients R² ranging from 0.918 to 0.995 for the linear least squares fitting.As JRC increases from 2-4 to 18-20,the cohesion increases by 86.32%whenα=15°,while the cohesion decreases by 27.93%whenα=75°.The differences in roughness characteristics of shear failure surface induced byαresult in anisotropic post-peak AE responses,which is characterized by active AE signals whenαis small and quiet AE signals for a largeα.For a given JRC=6-8 andσ_(n)=1 MPa,asαincreases,the accumulative AE counts increase by 224.31%(αincreased from 15°to 60°),and then decrease by 14.68%(αincreased from 60°to 75°).The shear failure surface is formed along the weak interlayer whenα=15°and penetrates the layered matrix whenα=60°.Whenα=15°,as σ_(n) increases,the adjacent weak interlayer induces a change in the direction of tensile cracks propagation,resulting in a stepped pattern of cracks distribution.The increase in JRC intensifies roughness characteristics of shear failure surface for a smallα,however,it is not pronounced for a largeα.The findings will contribute to a better understanding of the mechanical responses and failure mechanisms of the layered rocks subjected to shear loads.
文摘Carbon emissions embodied in international trade of China during 1997-2007 are accounted by input-output method based on Chinese input-output table and global trade analysis project database.It is revealed that carbon emissions embodied in imports and exports both increased during 1997-2007,but carbon emissions embodied in exports are greater than those embodied in imports,China is a net export nation in embodied carbon.The net exports of embodied carbon account for about 10.82%of the total carbon emissions in 1997,dropped to 7.15%in 2002,increased to 13.13%in 2006,and slightly dropped to 12.64%in 2007.Low-end position of international industry division is an objective factor of being a net exporter of embodied carbon for China,and usage of a large amount of obsolete energy-using equipments wasted much energy and increased carbon emissions embodied in exports. Importers should take more responsibilities for carbon emissions embodied in trade,and China should take a certain responsibility for unreasonable energy dissipations too.
基金support from the Post-doctoral Foundation Project of Tangshan Normal University(no.2018A03)the National Natural Science Foundation of China(no.21771141).
文摘A 24-metal Cd_((II))-Sm_((III))nanocluster[Cd_(18)Sm_(6)L_(9)(OAc)_(3)_(6)](CSN)was constructed from a new flexible Schiff base ligand.It can be used as a probe to detect 2,6-dichloro-4-nitroaniline(DCN,LOD:0.67-0.75μM),which is not influenced by the presence of other pesticides.The response behavior of CSN to DCN is expressed using a first-order equation 1/I_(475nm)+1/I_(645nm)+1/I_(945nm)=A[DCN]+B,and it is used to determine DCN concentrations in the extract of fruits.For example,for the concentration determination of DCN in carrot extract,the ranges of recovery and RSD are 96.11-103.50%and 0.95-4.12%,respectively.
基金supported by the National Natural Science Foundation of China(No.21771141)Key Foundation for High-level Talents Innovation Technology Projects of Wenzhou(2019).
文摘A 1-D coordination polymer[Sm(HL)_(2)(NO_(3))]_(n)(1)was constructed using a new flexible Schiff base ligand that has a long-chain(CH_(2))10 backbone.The Schiff base ligand exhibits a linear coordination configuration,resulting in the“zig-zag”structure of 1.Besides the ligand-centered emission,1 displays typical visible and NIR luminescence of Sm^(3+).Interestingly,1 shows dual-emissive response to metal ions,especially to Co^(2+)at the ppm level.
基金Financial support was from the National Natural Science Foundation of China(Nos.51773021,51911530197,U1663229)Six Talent Peaks Project in Jiangsu Province(No.XCL-102)the Talent Project of Jiangsu Specially-Appointed Professor,Natural Science Fund for Colleges and Universities in Jiangsu Province(No.19KJA430002)。
文摘Smart materials,such as stimuli-responsive luminescence,have attracted much attentions due to their potential application in semiconductor filed.In this context,platinum complexes of(dfppy-DC)Pt(acac) and(dfppy-O-DC)Pt(acac) were prepared and characterized,in which(2-(4',6'-difluorophenyl)pyridinato-N,C2')(2,4-pentanedionato-0,0)Pt(Ⅱ) was used as the planar emission core and 9-(4-(phenylsulfonyl)phenyl)-9 H-carbazole(DC) was regard as the bent pendent.Both platinum complexes showed bright emission in solution and solid state,concomitant with charming external-stimuli-responsive emission under mechanical grinding,organic solvent vapors and pressure.The change emission color spanned from yellow to near-infrared region.Using the platinum complexes as the dopant,solution processable organic light-emitting diodes(OLEDs) were fabricated and a maximum external quantum efficiency of ~18% was achieved,which is the highest value among the reported solution-processable OLEDs based on externalstimuli-responsive luminescence.This research demonstrated that platinum complex can show promising stimuli responsive emission via ingenious molecular design,indicating a novel way for developing the smart materials in semiconductor filed.
基金Financial and data support for this work is provided by the U.S. Environmental Protection Agency (No. GS-10F-0205T)partly supported by the funding of Guangdong Provincial Key Laboratory of Atmospheric Environment and Pollution Control (No. h2xj D612004 Ш )+1 种基金the funding of State Environmental Protection Key Laboratory of Sources and Control of Air Pollution Complex (No. SCAPC201308)the project of Atmospheric Haze Collaboration Control Technology Design (No. XDB05030400) from Chinese Academy of Sciences
文摘This article describes the development and implementations of a novel software platform that supports real-time, science-based policy making on air quality through a user-friendly interface. The software, RSM-VAT, uses a response surface modeling（RSM） methodology and serves as a visualization and analysis tool（VAT） for three-dimensional air quality data obtained by atmospheric models. The software features a number of powerful and intuitive data visualization functions for illustrating the complex nonlinear relationship between emission reductions and air quality benefits. The case study of contiguous U.S.demonstrates that the enhanced RSM-VAT is capable of reproducing the air quality model results with Normalized Mean Bias 〈 2% and assisting in air quality policy making in near real time.
基金Project supported by the Special Fund for Basic Scientific Research of Central Universities(21lzujbkyxs009).
文摘Inter-provincial carbon compensation is an important means for a country to realize regional environmental protection and achieve coordinated regional development and realize the carbon neutral goal.It is easier to realize inter-provincial carbon compensation compared with the national level.Based on the multi-regional input-output model and the input-output data of 30 provinces in China,this study measured the carbon transfer in,carbon transfer out and net carbon transfer of each province,and based on the undesirable slacks-based measurement model under the common frontier,the provinces were given the shadow price of carbon emission in line with the situation of the local economic development,resource endowment,and industrial structure,and based on which,the amount of carbon compensation of each province was measured.The results show that:China's provinces and regions have a larger share of trade-implied carbon emissions;the net carbon transfer in areas mainly concentrated in the traditional energy provinces,which provide industrial products for other regions and undertake the transfer of carbon emissions,and become the main carbon compensation recipient areas;the net carbon transfer out is mainly concentrated in the economically developed and densely populated areas such as Beijing-Tianjin region and the eastern and southern coasts,which satisfy the end-consumption by purchasing a large number of industrial products and generate a large amount of carbon emissions.Transfer out;becoming the main carbon offset payment area.Based on the results of this study,it is proposed to improve the national provincial carbon offset mechanism and implement a differentiated and synergistic carbon emission reduction cooperation approach.The research program of this study can provide a reference for the development of inter-regional carbon offset programs.
