To study the mechanism of rockburst and its spatio-temporal evolution criterion,a rockburst simulation experiment was performed on granite specimens,each with a prefabricated circular hole,under different lateral load...To study the mechanism of rockburst and its spatio-temporal evolution criterion,a rockburst simulation experiment was performed on granite specimens,each with a prefabricated circular hole,under different lateral loads.Using micro camera,acoustic emission(AE)system,and infrared thermal imager,the AE characteristics and thermal radiation temperature migration were studied during the rockburst process.Then,the failure mode and damage evolution of the surrounding rock were analyzed.The results demonstrate that increasing the lateral load can first increase and then reduce the bearing capacity of the hole.In this experiment,the hole failure process could be divided into four periods:quiet,particle ejection,stability failure and collapse.Correspondingly,the AE signals evolved from a calm stage,to have intermittent appearance;then,they were continuous with a sudden increase,and finally increased dramatically.The failure of the surrounding rock was mainly tensile failure,while shear failure tended to first increase and then decrease.Meanwhile,damage to the hole increased gradually during the particle ejection period,whereas damage to the rockburst mainly occurred in the stability failure period.The thermal radiation temperature migration exhibited warming in shallow parts,inward expansion,cooling in the shallow parts with free surface heating,inward expansion,a sudden rise in temperature of the rockburst pits,and finally specimen failure.The initial reinforcement support should fully contribute to surface support.Furthermore,an appropriate tensile capacity and good energy absorption capacity should be established in support systems for high-stress roadways.展开更多
Climate sequences can be applied to defining sensitive climate zones, and then the mining of spatio-temporal teleconnection patterns is useful for learning from the past and preparing for the future. However, scale-de...Climate sequences can be applied to defining sensitive climate zones, and then the mining of spatio-temporal teleconnection patterns is useful for learning from the past and preparing for the future. However, scale-dependency in this kind of pattern is still not well handled by existing work. Therefore, in this study, the multi-scale regionalization is embedded into the spatio-temporal teleconnection pattern mining between anomalous sea and land climatic events. A modified scale-space clustering algorithm is first developed to group climate sequences into multi-scale climate zones. Then, scale variance analysis method is employed to identify climate zones at characteristic scales, indicating the main characteristics of geographical phenomena. Finally, by using the climate zones identified at characteristic scales, a time association rule mining algorithm based on sliding time windows is employed to discover spatio-temporal teleconnection patterns. Experiments on sea surface temperature, sea level pressure, land precipitation and land temperature datasets show that many patterns obtained by the multi-scale approach are coincident with prior knowledge, indicating that this method is effective and reasonable. In addition, some unknown teleconnection patterns discovered from the multi-scale approach can be further used to guide the prediction of land climate.展开更多
To reveal stress distribution and crack propagation of Brazilian discs under impact loads, dynamic tests were conducted with SHPB （split Hopkinson pressure bar） device. Stress states of specimens were monitored with...To reveal stress distribution and crack propagation of Brazilian discs under impact loads, dynamic tests were conducted with SHPB （split Hopkinson pressure bar） device. Stress states of specimens were monitored with strain gauges on specimen surface and SHPB bars. The failure process of specimen was recorded by ultra speed camera FASTCAM SAI.1 （675 000 fps）. Stress histories from strain gauges offer comprehensive information to evaluate the stress equilibrium of specimen in time and space. When a slowly rising load （with loading rates less than 1 200 N/s for d 50 mm bar） is applied, there is usually good stress equilibrium in specimen. The stress distribution after equilibrium is similar to its static counterpart. And the first crack initiates at the disc center and propagates along the load direction. But with the front of incident wave becoming steep, it is hard for specimens to get to stress equilibrium. The first crack may appear anywhere on the specimen together with multiple randomly distributed secondary cracks. For a valid dynamic Brazil test with stress equilibrium, the specimen will break into two halves neatly. While for tests with stress disequilibrium, missing strap may be found when broken halves of specimens are put together. For those specimens broken up neatly at center but having missing wedges at the loading areas, it is usually subjected to local buckling from SHPB bars.展开更多
Background:Pectin is a key substance involved in cell wall development,and the galacturonosyltransferases(GAUTs)gene family is a critical participant in the pectin synthesis pathway.Systematic and comprehensive resear...Background:Pectin is a key substance involved in cell wall development,and the galacturonosyltransferases(GAUTs)gene family is a critical participant in the pectin synthesis pathway.Systematic and comprehensive research on GAUTs has not been performed in cotton.Analysis of the evolution and expression patterns of the GAUT gene family in different cotton species is needed to in crease kno wledge of the functi on of pectin in cotto n fiber development.Results:In this study,we have identified 131 GAUT genes in the genomes of four Gossypium species(G.raimondii,G barbadense,G.hirsutum,and G.arboreum),and classified them as GAUT-A,GAUT-B and GAUT-C,which coding probable galacturonosyltransferases.Among them,the GAUT genes encode proteins GAUT1 to GAUT15.All GAUT proteins except for GAUT7 contai n a con served glycosyl transferase family 8 domain(H-DN-A-SW-S-V-H-T-F).The conserved sequence of GAUT7 is PLN(phospholamban)02769 domain.According to c/s-elemet analysis,GAUT genes transcript levels may be regulated by horm ones such as JA,GA,SA,ABA,Me-JA,and IA A.The evoluti on and transcription patterns of the GAUT gene family in different cotton species and the transcript levels in upland cotton lines with different fiber st「ength were analyzed.Peak transcript level of GhGAUT genes have been observed before 15 DPA.In the six materials with high fiber strength,the transcription of GhGAUT genes were concentrated from 10 to 15 DPA;while the highest transcript levels in low fiber st「ength materials were detected between 5 and 10 DPA.These results lays the foundation for future research on gene function during cotton fiber development.Conclusions:The GAUT gene family may affect cotton fiber development,including fiber elongation and fiber thickening.In the low strength fiber lines,GAUTs mainly participate in fiber elongation,whereas their major effect on cotton with high strength fiber is related to both elongation and thickening.展开更多
基金Project(2017YFC0603003)supported by the National Key Research and Development Project of ChinaProjects(51974009,51674008)supported by the National Natural Science Foundation of China+3 种基金Project(201904a07020010)supported by the Key Research and Development Program of Anhui Province,ChinaProject(2018D187)supported by the Leading Talent Project of Anhui“Special Support Program”,Anhui Provincial Academic and Technology Leaders Research Activities Funding,ChinaProject(gxbjZD2016051)supported by the Excellence Talent Training Program of High School,ChinaProject(2019CX2008)supported by the Graduate Innovation Fund of Anhui University of Science and Technology,China。
文摘To study the mechanism of rockburst and its spatio-temporal evolution criterion,a rockburst simulation experiment was performed on granite specimens,each with a prefabricated circular hole,under different lateral loads.Using micro camera,acoustic emission(AE)system,and infrared thermal imager,the AE characteristics and thermal radiation temperature migration were studied during the rockburst process.Then,the failure mode and damage evolution of the surrounding rock were analyzed.The results demonstrate that increasing the lateral load can first increase and then reduce the bearing capacity of the hole.In this experiment,the hole failure process could be divided into four periods:quiet,particle ejection,stability failure and collapse.Correspondingly,the AE signals evolved from a calm stage,to have intermittent appearance;then,they were continuous with a sudden increase,and finally increased dramatically.The failure of the surrounding rock was mainly tensile failure,while shear failure tended to first increase and then decrease.Meanwhile,damage to the hole increased gradually during the particle ejection period,whereas damage to the rockburst mainly occurred in the stability failure period.The thermal radiation temperature migration exhibited warming in shallow parts,inward expansion,cooling in the shallow parts with free surface heating,inward expansion,a sudden rise in temperature of the rockburst pits,and finally specimen failure.The initial reinforcement support should fully contribute to surface support.Furthermore,an appropriate tensile capacity and good energy absorption capacity should be established in support systems for high-stress roadways.
基金Projects(41601424,41171351)supported by the National Natural Science Foundation of ChinaProject(2012CB719906)supported by the National Basic Research Program of China(973 Program)+2 种基金Project(14JJ1007)supported by the Hunan Natural Science Fund for Distinguished Young Scholars,ChinaProject(2017M610486)supported by the China Postdoctoral Science FoundationProjects(2017YFB0503700,2017YFB0503601)supported by the National Key Research and Development Foundation of China
文摘Climate sequences can be applied to defining sensitive climate zones, and then the mining of spatio-temporal teleconnection patterns is useful for learning from the past and preparing for the future. However, scale-dependency in this kind of pattern is still not well handled by existing work. Therefore, in this study, the multi-scale regionalization is embedded into the spatio-temporal teleconnection pattern mining between anomalous sea and land climatic events. A modified scale-space clustering algorithm is first developed to group climate sequences into multi-scale climate zones. Then, scale variance analysis method is employed to identify climate zones at characteristic scales, indicating the main characteristics of geographical phenomena. Finally, by using the climate zones identified at characteristic scales, a time association rule mining algorithm based on sliding time windows is employed to discover spatio-temporal teleconnection patterns. Experiments on sea surface temperature, sea level pressure, land precipitation and land temperature datasets show that many patterns obtained by the multi-scale approach are coincident with prior knowledge, indicating that this method is effective and reasonable. In addition, some unknown teleconnection patterns discovered from the multi-scale approach can be further used to guide the prediction of land climate.
基金Projects(50904079, 51274254, 50934006) supported by the National Natural Science Foundation of ChinaProject(2010CB732004) supported by the National Basic Research Program of ChinaProject(NCET-11-0528) supported by Program for New Century Excellent Talents in University of China
文摘To reveal stress distribution and crack propagation of Brazilian discs under impact loads, dynamic tests were conducted with SHPB （split Hopkinson pressure bar） device. Stress states of specimens were monitored with strain gauges on specimen surface and SHPB bars. The failure process of specimen was recorded by ultra speed camera FASTCAM SAI.1 （675 000 fps）. Stress histories from strain gauges offer comprehensive information to evaluate the stress equilibrium of specimen in time and space. When a slowly rising load （with loading rates less than 1 200 N/s for d 50 mm bar） is applied, there is usually good stress equilibrium in specimen. The stress distribution after equilibrium is similar to its static counterpart. And the first crack initiates at the disc center and propagates along the load direction. But with the front of incident wave becoming steep, it is hard for specimens to get to stress equilibrium. The first crack may appear anywhere on the specimen together with multiple randomly distributed secondary cracks. For a valid dynamic Brazil test with stress equilibrium, the specimen will break into two halves neatly. While for tests with stress disequilibrium, missing strap may be found when broken halves of specimens are put together. For those specimens broken up neatly at center but having missing wedges at the loading areas, it is usually subjected to local buckling from SHPB bars.
基金the Major Research Plan of National Natural Science Foundation of China(NO.31690093)the National Agricultural Science and Technology Innovation project for CAAS(CAAS-ASTIP-2016-ICR)the Central Level of the Scientific Research Institutes for Basic R&D Special Fund Business(Y2017PT51)。
文摘Background:Pectin is a key substance involved in cell wall development,and the galacturonosyltransferases(GAUTs)gene family is a critical participant in the pectin synthesis pathway.Systematic and comprehensive research on GAUTs has not been performed in cotton.Analysis of the evolution and expression patterns of the GAUT gene family in different cotton species is needed to in crease kno wledge of the functi on of pectin in cotto n fiber development.Results:In this study,we have identified 131 GAUT genes in the genomes of four Gossypium species(G.raimondii,G barbadense,G.hirsutum,and G.arboreum),and classified them as GAUT-A,GAUT-B and GAUT-C,which coding probable galacturonosyltransferases.Among them,the GAUT genes encode proteins GAUT1 to GAUT15.All GAUT proteins except for GAUT7 contai n a con served glycosyl transferase family 8 domain(H-DN-A-SW-S-V-H-T-F).The conserved sequence of GAUT7 is PLN(phospholamban)02769 domain.According to c/s-elemet analysis,GAUT genes transcript levels may be regulated by horm ones such as JA,GA,SA,ABA,Me-JA,and IA A.The evoluti on and transcription patterns of the GAUT gene family in different cotton species and the transcript levels in upland cotton lines with different fiber st「ength were analyzed.Peak transcript level of GhGAUT genes have been observed before 15 DPA.In the six materials with high fiber strength,the transcription of GhGAUT genes were concentrated from 10 to 15 DPA;while the highest transcript levels in low fiber st「ength materials were detected between 5 and 10 DPA.These results lays the foundation for future research on gene function during cotton fiber development.Conclusions:The GAUT gene family may affect cotton fiber development,including fiber elongation and fiber thickening.In the low strength fiber lines,GAUTs mainly participate in fiber elongation,whereas their major effect on cotton with high strength fiber is related to both elongation and thickening.
