The Bayan Har block is mainly bounded by the east Kunlun fault zone to the north, Garze-Yushu -Xianshuihe fault zone to the south and Longmenshan fault zone to the east (Fig. 1). In the past 20 years, large earthqua...The Bayan Har block is mainly bounded by the east Kunlun fault zone to the north, Garze-Yushu -Xianshuihe fault zone to the south and Longmenshan fault zone to the east (Fig. 1). In the past 20 years, large earthquakes have occurred frequently along this block's boundaries, which has received much attention among geoscientists. Whether large earthquakes will happen (and where) along this block's boundary faults in the future are two key problems that need to be addressed. This study calculates the accumulated tectonic stress and superposition of the coulomb stress caused by fault slip of 16 large earthquakes since 1904, and evaluates the possible locations of future earthquakes that may occur around this block.展开更多
Block boundary value methods(BBVMs)are extended in this paper to obtain the numerical solutions of nonlinear delay-differential-algebraic equations with singular perturbation(DDAESP).It is proved that the extended BBV...Block boundary value methods(BBVMs)are extended in this paper to obtain the numerical solutions of nonlinear delay-differential-algebraic equations with singular perturbation(DDAESP).It is proved that the extended BBVMs in some suitable conditions are globally stable and can obtain a unique exact solution of the DDAESP.Besides,whenever the classic Lipschitz conditions are satisfied,the extended BBVMs are preconsistent and pth order consistent.Moreover,through some numerical examples,the correctness of the theoretical results and computational validity of the extended BBVMs is further confirmed.展开更多
On the basis of the velocity field results of horizontal crustal movement obtained from GPS measurements during the periods of 1993-1999, 1999-2001 and 2001-2003 in the northeastern margin of Qinghai-Xizang block, and...On the basis of the velocity field results of horizontal crustal movement obtained from GPS measurements during the periods of 1993-1999, 1999-2001 and 2001-2003 in the northeastern margin of Qinghai-Xizang block, and by the inversion of negative dislocation model for the elastic block boundaries, we provide in this paper a qualitative analysis and quantitative description for the difference of motion and deformation between the tectonic blocks and their boundary faults, time-space distribution of tectonic strain field, and locations with highly accumulated strain energy and correlative intensity. Furthermore, taking the regional tectonics and block strain into full consideration, we investigate the common features of background precursors relating to location prediction for M greater than or equal 6 earthquakes.展开更多
Based on gravity data processed with the matched filter, depth continuation and horizontal gradient we obtained the spatial distribution of the gravity field and made analyses of the tectonic framework of South China....Based on gravity data processed with the matched filter, depth continuation and horizontal gradient we obtained the spatial distribution of the gravity field and made analyses of the tectonic framework of South China. Then, inversion was conducted for the depth to study the depth variation of the boundary between the crust and upper mantle, namely the Mohorovicic discontinuity (Moho). The results demonstrate that the Moho depth in South China ranges from 30 to 40 km, and the crust thins from west to east, 27-29 km under the continent margin and shallow sea. We think it possible that the Tanlu fault crosses the Yangtze River and extends southwards along the Ganjiang and Wuchuan-Sihui faults to the South China Sea, and that there is an E-W hidden structural belt along 24.5°-26°.展开更多
Crustal thickness and composition are closely related to geology and tectonic evolution of the region.Studying the differences in the crustal thickness and composition of the South China Block(SCB)is important to gain...Crustal thickness and composition are closely related to geology and tectonic evolution of the region.Studying the differences in the crustal thickness and composition of the South China Block(SCB)is important to gain a comprehensive understanding of multi-phase amalgamation,breakup,reworking,and regional geodynamic processes.In this study,teleseismic data from 135 high-density portable broadband stations from Sino Probe were processed using Common Conversion Point(CCP)stacking and H-κstacking methods.The Moho depth and P-wave and S-wave velocity ratio(V_(p)/V_(s))were studied.Our results revealed several insights about the tectonic processes in the SCB.First,the crustal structure and V_(p)/V_(s)ratios of the Cathaysia Block,Jiangnan Orogenic Belt,and Yangtze Block were significantly different.The average depth of the Moho in the Cathaysia Block was approximately 31 km,and the V_(p)/V_(s)ratios increased from the inland area(1.66)to the coastal area(1.78),indicating the oceanward increase of mafic proportion in the lower crust,which is related to the influence of the Paleo-Pacific Plate westward subduction.Second,the crustal thickness of Jiangnan Orogenic Belt deepens from east ca.31 to the west ca.42 km and the V_(p)/V_(s)ratios varied from 1.75 to 1.64,illustrating a relatively felsic crust,which could have been related to the Mesozoic upper crustal thickening under compression followed by the lower crust removal under the extensional background.Third,the average crustal thickness of the Yangtze Block was 42 km,and the V_(p)/V_(s)ratios ranged from 1.64 to 1.84,presenting a positive correlation between the Moho depth and the V_(p)/V_(s)ratio,which is explained by the relatively thick mafic lower crust.Based on the variations in the crustal structure and V_(p)/V_(s)ratios of the profile,we inferred that the central part of the Jiangnan Orogenic Belt was bounded by the Jiangshan-Shaoxing-Hengyang in the east and the Jiujiang-Shitai-Jishou in the west.The small-scale Moho depth undulations at the intersection of the Cathaysia Block and the Jiangnan Orogenic Belt could be related to the Mesozoic compression-extension geodynamic transformation.展开更多
During the second period of China "Tanyue" Project, the explorer will softland on the moon. The cushion engines are used to decelerate the explorer and reduce the impact on the lunar ground. It is necessary to study...During the second period of China "Tanyue" Project, the explorer will softland on the moon. The cushion engines are used to decelerate the explorer and reduce the impact on the lunar ground. It is necessary to study its plume effects on the explorer component. The self-developed PWS (Plume WorkStation) software based on direct simulation Monte Carlo (DSMC) method is used to simulate the plume effects of two 150 N engines. Due to the complex structure of the explorer, PWS uses a decoupling method to treat the boundary mesh, which mainly interacts with simulation particles, and has no relation with the computational grids. After the analytical expressions of plane surfaces and curved surfaces of each boundary block are given, the particle position within or without the boundary blocks can be easily determined. Finally the 3D plume field of two 150 N engines is simulated. The pressure, temperature and velocity distributions of plume field are clearly presented by three characteristic slices. The aerodynamic effects on the explorer bottom, the landfall legs and antenna are separately shown. The compression influence on the plume flow of four landfall legs can be observed.展开更多
A CoCe/ZSM-5 catalyst was prepared by ultrasonic-assisted impregnation for the catalytic combustion of toluene.To study the effect of Na+on catalytic performance of CoCe/ZSM-5 catalysts,a series of different Si/Al ZSM...A CoCe/ZSM-5 catalyst was prepared by ultrasonic-assisted impregnation for the catalytic combustion of toluene.To study the effect of Na+on catalytic performance of CoCe/ZSM-5 catalysts,a series of different Si/Al ZSM-5 zeolites and catalysts doped with Na were synthesized.The experimental results show that 0.71 wt%Na+can inhibit active growth,generate more active small crystal grains,and promote improvement of the catalytic activity by the grain boundary segregation block mechanism,and the catalyst with 0.71 wt%of Na shows toluene conversion of 90 vol%at 250℃.Over 0.71 wt%of Na+content will neutralize the acid centre of the catalyst,lowering the specific surface area of the catalyst and resulting in a gradual decrease in the catalytic activity.展开更多
基金supported by Geological Survey programs from Geological Survey of China(No.1212011120163 and 12120114002101)Basic Science Research Fund of the Institute of Geomechanics,CAGS (No.DZLXJK201212)National Natural Science Foundation of China (No.41171009)
文摘The Bayan Har block is mainly bounded by the east Kunlun fault zone to the north, Garze-Yushu -Xianshuihe fault zone to the south and Longmenshan fault zone to the east (Fig. 1). In the past 20 years, large earthquakes have occurred frequently along this block's boundaries, which has received much attention among geoscientists. Whether large earthquakes will happen (and where) along this block's boundary faults in the future are two key problems that need to be addressed. This study calculates the accumulated tectonic stress and superposition of the coulomb stress caused by fault slip of 16 large earthquakes since 1904, and evaluates the possible locations of future earthquakes that may occur around this block.
基金supported by the National Key R&D Program of China(2020YFA0709800)the National Natural Science Foundation of China(Nos.11901577,11971481,12071481,12001539)+4 种基金the Natural Science Foundation of Hunan(No.S2017JJQNJJ-0764)the fund from Hunan Provincial Key Laboratory of Mathematical Modeling and Analysis in Engineering(No.2018MMAEZD004)the Basic Research Foundation of National Numerical Wind Tunnel Project(No.NNW2018-ZT4A08)the Research Fund of National University of Defense Technology(No.ZK19-37)The science and technology innovation Program of Hunan Province(No.2020RC2039).
文摘Block boundary value methods(BBVMs)are extended in this paper to obtain the numerical solutions of nonlinear delay-differential-algebraic equations with singular perturbation(DDAESP).It is proved that the extended BBVMs in some suitable conditions are globally stable and can obtain a unique exact solution of the DDAESP.Besides,whenever the classic Lipschitz conditions are satisfied,the extended BBVMs are preconsistent and pth order consistent.Moreover,through some numerical examples,the correctness of the theoretical results and computational validity of the extended BBVMs is further confirmed.
基金Joint Seismological Science Foundation (603001)Project of China Earthquake Administration during the tenth five-year (100501-04).
文摘On the basis of the velocity field results of horizontal crustal movement obtained from GPS measurements during the periods of 1993-1999, 1999-2001 and 2001-2003 in the northeastern margin of Qinghai-Xizang block, and by the inversion of negative dislocation model for the elastic block boundaries, we provide in this paper a qualitative analysis and quantitative description for the difference of motion and deformation between the tectonic blocks and their boundary faults, time-space distribution of tectonic strain field, and locations with highly accumulated strain energy and correlative intensity. Furthermore, taking the regional tectonics and block strain into full consideration, we investigate the common features of background precursors relating to location prediction for M greater than or equal 6 earthquakes.
基金Th is study was carried out during 2001-2003 and financially supposed by the National Natural Science Foundation of China(No.40074020)
文摘Based on gravity data processed with the matched filter, depth continuation and horizontal gradient we obtained the spatial distribution of the gravity field and made analyses of the tectonic framework of South China. Then, inversion was conducted for the depth to study the depth variation of the boundary between the crust and upper mantle, namely the Mohorovicic discontinuity (Moho). The results demonstrate that the Moho depth in South China ranges from 30 to 40 km, and the crust thins from west to east, 27-29 km under the continent margin and shallow sea. We think it possible that the Tanlu fault crosses the Yangtze River and extends southwards along the Ganjiang and Wuchuan-Sihui faults to the South China Sea, and that there is an E-W hidden structural belt along 24.5°-26°.
基金supported by the National Natural Science Foundation of China(Grant Nos.41630320,92062108)the China Geological Survey Project(Grant No.DD20190012)open fund from the Key Laboratory of Deep-Earth Dynamics of Ministry of Natural Resource,Institute of Geology,Chinese Academy of Geological Sciences(Grant No.J1901-16)。
文摘Crustal thickness and composition are closely related to geology and tectonic evolution of the region.Studying the differences in the crustal thickness and composition of the South China Block(SCB)is important to gain a comprehensive understanding of multi-phase amalgamation,breakup,reworking,and regional geodynamic processes.In this study,teleseismic data from 135 high-density portable broadband stations from Sino Probe were processed using Common Conversion Point(CCP)stacking and H-κstacking methods.The Moho depth and P-wave and S-wave velocity ratio(V_(p)/V_(s))were studied.Our results revealed several insights about the tectonic processes in the SCB.First,the crustal structure and V_(p)/V_(s)ratios of the Cathaysia Block,Jiangnan Orogenic Belt,and Yangtze Block were significantly different.The average depth of the Moho in the Cathaysia Block was approximately 31 km,and the V_(p)/V_(s)ratios increased from the inland area(1.66)to the coastal area(1.78),indicating the oceanward increase of mafic proportion in the lower crust,which is related to the influence of the Paleo-Pacific Plate westward subduction.Second,the crustal thickness of Jiangnan Orogenic Belt deepens from east ca.31 to the west ca.42 km and the V_(p)/V_(s)ratios varied from 1.75 to 1.64,illustrating a relatively felsic crust,which could have been related to the Mesozoic upper crustal thickening under compression followed by the lower crust removal under the extensional background.Third,the average crustal thickness of the Yangtze Block was 42 km,and the V_(p)/V_(s)ratios ranged from 1.64 to 1.84,presenting a positive correlation between the Moho depth and the V_(p)/V_(s)ratio,which is explained by the relatively thick mafic lower crust.Based on the variations in the crustal structure and V_(p)/V_(s)ratios of the profile,we inferred that the central part of the Jiangnan Orogenic Belt was bounded by the Jiangshan-Shaoxing-Hengyang in the east and the Jiujiang-Shitai-Jishou in the west.The small-scale Moho depth undulations at the intersection of the Cathaysia Block and the Jiangnan Orogenic Belt could be related to the Mesozoic compression-extension geodynamic transformation.
基金supported by the "Tanyue" Period Two Research Projects
文摘During the second period of China "Tanyue" Project, the explorer will softland on the moon. The cushion engines are used to decelerate the explorer and reduce the impact on the lunar ground. It is necessary to study its plume effects on the explorer component. The self-developed PWS (Plume WorkStation) software based on direct simulation Monte Carlo (DSMC) method is used to simulate the plume effects of two 150 N engines. Due to the complex structure of the explorer, PWS uses a decoupling method to treat the boundary mesh, which mainly interacts with simulation particles, and has no relation with the computational grids. After the analytical expressions of plane surfaces and curved surfaces of each boundary block are given, the particle position within or without the boundary blocks can be easily determined. Finally the 3D plume field of two 150 N engines is simulated. The pressure, temperature and velocity distributions of plume field are clearly presented by three characteristic slices. The aerodynamic effects on the explorer bottom, the landfall legs and antenna are separately shown. The compression influence on the plume flow of four landfall legs can be observed.
基金Project supported by Science and Technology Department of Jiangsu Province(BE2016769).
文摘A CoCe/ZSM-5 catalyst was prepared by ultrasonic-assisted impregnation for the catalytic combustion of toluene.To study the effect of Na+on catalytic performance of CoCe/ZSM-5 catalysts,a series of different Si/Al ZSM-5 zeolites and catalysts doped with Na were synthesized.The experimental results show that 0.71 wt%Na+can inhibit active growth,generate more active small crystal grains,and promote improvement of the catalytic activity by the grain boundary segregation block mechanism,and the catalyst with 0.71 wt%of Na shows toluene conversion of 90 vol%at 250℃.Over 0.71 wt%of Na+content will neutralize the acid centre of the catalyst,lowering the specific surface area of the catalyst and resulting in a gradual decrease in the catalytic activity.