Unveiling the underlying physical mechanisms governing the fracture of brittle rocks is imperative for preventing rockbursts.The novelty of this study lies in the analysis of the dynamic response process of rock three...Unveiling the underlying physical mechanisms governing the fracture of brittle rocks is imperative for preventing rockbursts.The novelty of this study lies in the analysis of the dynamic response process of rock three-dimensional(3D)deformation under true triaxial stress,and the surge behavior of timedependent multifractal spectrum has been successfully used to warn of progressive failure inside the rock.Firstly,this study analyzed the dynamic adjustment trajectory of rock deformation,specifically lateral strain,within the framework of the Poisson effect.This analysis highlighted the intricate dependence of rock mechanical properties on the intermediate principal stress.Secondly,by defining the crack interval function(ICF),this study compared the disparities between the two crack growth stages(strengthening stage and weakening stage)under varying stress levels.It was found that the fracture activity of granite system has significant multifractal characteristics.Notably,the multifractal spectrum emerges as a valuable tool for characterizing the distinct fracture properties of rocks,encompassing both the crack scale and the associated energy.Finally,a quantitative criterion grounded in the multifractal parameters of the acoustic emission(AE)time series was formulated,and it indicates that the abrupt changes observed in the time-dependent fractal spectra can serve as precursor indicators for the progressive development of rockbursts.展开更多
With the development of intelligent flexible manufacturing,traditional industrial manipulators with a single configuration are difficult to meet a variety of tasks.Reconfigurable robots have developed rapidly which co...With the development of intelligent flexible manufacturing,traditional industrial manipulators with a single configuration are difficult to meet a variety of tasks.Reconfigurable robots have developed rapidly which could change their configurations and end effectors for different tasks.The reconfigurable connecting mechanism(RCM)is a core component of reconfigurable robots.In this paper,two types of intelligent modularized RCMs with light weight,high payload,and large pose(position and attitude)error tolerance are developed.One is driven by shape memory alloy(SMA)and recovery spring.It is locked by steel balls and key.The other is driven by electromagnetic coil and locked by permanent magnet and key.The locking principle,mechanical system and control system of the two RCMs are detailed introduced.Both of them meet the requirements of high precision and high payload in the industrial field.Finally,the developed RCMs are respectively integrated to a practical robot and experimented.The experiment results verified the performance of the two RCMs.展开更多
By integrating surface geology,seismic data,resistivity sections,and drilling data,the structural deformation characteristics of the frontier fault of thrust nappes were delineated in detail.The frontier fault of thru...By integrating surface geology,seismic data,resistivity sections,and drilling data,the structural deformation characteristics of the frontier fault of thrust nappes were delineated in detail.The frontier fault of thrust nappes in northwest Scihuan Basin is a buried thrust fault with partial exposure in the Xiangshuichang-Jiangyou area,forming fault propagation folds in the hanging-wall and without presenting large-scale basin-ward displacement along the gypsum-salt layer of the Triassic Jialingjiang Formation to the Triassic Leikoupo Formation.The southwestern portion of the frontier fault of thrust nappes(southwest of Houba)forms fault bend folds with multiple ramps and flats,giving rise to the Zhongba anticline due to hanging-wall slip along the upper flat of the Jialingjiang Formation.In contrast,the northeastern portion of the frontier fault of thrust nappes(northeast of Houba)presents upward steepening geometry,leading to surface exposure of Cambrian in its hanging-wall.With the frontier fault of thrust nappes as the boundary between the Longmenshan Mountain and the Sichuan Basin,the imbricated structural belt in the hanging-wall thrusted strongly in the Indosinian orogeny and was reactivated in the Himalayan orogeny,while the piedmont buried structural belt in the footwall was formed in the Himalayan orogeny.In the footwall of the frontier fault of thrust nappes,the piedmont buried structural belt has good configuration of source rocks,reservoir rocks and cap rocks,presenting good potential to form large gas reservoirs.In comparison,the hanging-wall of the frontier fault of thrust nappes north of Chonghua has poor condition of oil/gas preservation due to the surface exposure of Triassic and deeper strata,while the fault blocks in the hanging-wall from Chonghua to Wudu,with Jurassic cover and thicker gypsum-salt layer of the Jialingjiang formation,has relative better oil/gas preservation conditions and thus potential of oil/gas accumulation.The frontier fault of thrust nappes is not only the boundary between the Longmenshan Mountain and the Sichuan Basin,but also the boundary of the oil/gas accumulation system in northwestern Sichuan Basin.展开更多
In this paper, a model of two-wave mixing in the photorefractive crystal, which takes account of the difference in spatial frequency in a beam, has been built to study the image enhancement effect in coherent optical ...In this paper, a model of two-wave mixing in the photorefractive crystal, which takes account of the difference in spatial frequency in a beam, has been built to study the image enhancement effect in coherent optical amplification. Based on the theoretical analysis of the model, the gain distribution for each pixel in the signal beam has been obtained. It shows that the unevenness of the gain is induced by the difference in spatial frequency in the beam. The factors that impact on the uniformity of image enhancement have been analyzed. As an example, the effects of these factors in a given photorefractive crystal have been studied through simulation.展开更多
Since 2014,great gas discoveries have been achieved in the Upper Paleozoic Shuangyushi zone in the piedmont zone of the Longmenshan mountains,northwestern Sichuan Basin,where multiple gas wells with industrial flows h...Since 2014,great gas discoveries have been achieved in the Upper Paleozoic Shuangyushi zone in the piedmont zone of the Longmenshan mountains,northwestern Sichuan Basin,where multiple gas wells with industrial flows have been drilled and completed successively in the Middle Permian Qixia Fm and Middle Devonian Guanwushan Fm,etc.Along with the steady progress of exploration there,to make a further in-depth study on the characteristics of the frontal–piedmont zones in the Longmenshan thrust–nappe structures will be of great significance to both a better understanding of Upper Paleozoic gas reservoirs in this study area and the expansion of oil and gas exploration field.In view of this,based on the newly deployed 3D seismic surveys,gravity–magnetic–electronic data,and practical drilling information from exploration wells like Well ST 9,the characteristics of the frontal–piedmont zones in the Longmenshan thrust–nappe structures are analyzed as well as the features of the buried structures,gas reservoir forming conditions and exploration prospect there.The following findings were obtained:(1)A huge buried structure belt is developed underlying the Longmenshan front fault belt No.1(LSFFB 1)and marine strata are thus formed below the Lower Triassic Jialingjiang Fm due to the roles of compressive folding,extrusion and deformation;(2)The detachment horizons from LSFFB 1 go from shallower in the south to deeper in the north,turning from Cambrian slipping in the south to basement-involved in the north.The Paleozoic and its overlying strata were overall uplifted with a higher degree northward and so did the strata between the up-thrown and down-thrown sides of the faults with a greater displacement distance and higher folding degree,resulting in that the Paleozoic strata in the north are 1500 higher uplifted than those in the south;(3)In the western Jiange and Guangyuan areas,the eastern LSFFB 1 presents a tectonic pattern of“three steps”as a whole.In conclusion,there are good gas reservoir forming conditions in LSFFB 1,the down-thrown sides of which cover an area of 1800 km2,where the Guanwushan Fm and Qixia Fm provide good accumulation and preservation conditions for gas reservoirs,which will become favorable gas exploration targets in the deep marine strata in NW Sichuan Basin.展开更多
基金funding support from the National Natural Science Foundation of China(Grant No.U2034207)the Natural Science Foundation of Hebei Province(Grant No.E2021210099).
文摘Unveiling the underlying physical mechanisms governing the fracture of brittle rocks is imperative for preventing rockbursts.The novelty of this study lies in the analysis of the dynamic response process of rock three-dimensional(3D)deformation under true triaxial stress,and the surge behavior of timedependent multifractal spectrum has been successfully used to warn of progressive failure inside the rock.Firstly,this study analyzed the dynamic adjustment trajectory of rock deformation,specifically lateral strain,within the framework of the Poisson effect.This analysis highlighted the intricate dependence of rock mechanical properties on the intermediate principal stress.Secondly,by defining the crack interval function(ICF),this study compared the disparities between the two crack growth stages(strengthening stage and weakening stage)under varying stress levels.It was found that the fracture activity of granite system has significant multifractal characteristics.Notably,the multifractal spectrum emerges as a valuable tool for characterizing the distinct fracture properties of rocks,encompassing both the crack scale and the associated energy.Finally,a quantitative criterion grounded in the multifractal parameters of the acoustic emission(AE)time series was formulated,and it indicates that the abrupt changes observed in the time-dependent fractal spectra can serve as precursor indicators for the progressive development of rockbursts.
基金Supported by National Key R&D Program of China(Grant No.2018YFB1304600)Guangdong Provincial Key Research and Development Program of China(Grant No.2019B090915001)+1 种基金Guangdong Provincial Special Support Program of China(Grant No.2017TX04X0071)Basic Research Program of Shenzhen City(Grant No.JCYJ20180507183610564).
文摘With the development of intelligent flexible manufacturing,traditional industrial manipulators with a single configuration are difficult to meet a variety of tasks.Reconfigurable robots have developed rapidly which could change their configurations and end effectors for different tasks.The reconfigurable connecting mechanism(RCM)is a core component of reconfigurable robots.In this paper,two types of intelligent modularized RCMs with light weight,high payload,and large pose(position and attitude)error tolerance are developed.One is driven by shape memory alloy(SMA)and recovery spring.It is locked by steel balls and key.The other is driven by electromagnetic coil and locked by permanent magnet and key.The locking principle,mechanical system and control system of the two RCMs are detailed introduced.Both of them meet the requirements of high precision and high payload in the industrial field.Finally,the developed RCMs are respectively integrated to a practical robot and experimented.The experiment results verified the performance of the two RCMs.
基金Supported by the National Natural Science Foundation of China(41872143)National Science and Technology Major Project of China(2016ZX05007-004)PetroChina Science and Technology Major Project(2016E-0604)。
文摘By integrating surface geology,seismic data,resistivity sections,and drilling data,the structural deformation characteristics of the frontier fault of thrust nappes were delineated in detail.The frontier fault of thrust nappes in northwest Scihuan Basin is a buried thrust fault with partial exposure in the Xiangshuichang-Jiangyou area,forming fault propagation folds in the hanging-wall and without presenting large-scale basin-ward displacement along the gypsum-salt layer of the Triassic Jialingjiang Formation to the Triassic Leikoupo Formation.The southwestern portion of the frontier fault of thrust nappes(southwest of Houba)forms fault bend folds with multiple ramps and flats,giving rise to the Zhongba anticline due to hanging-wall slip along the upper flat of the Jialingjiang Formation.In contrast,the northeastern portion of the frontier fault of thrust nappes(northeast of Houba)presents upward steepening geometry,leading to surface exposure of Cambrian in its hanging-wall.With the frontier fault of thrust nappes as the boundary between the Longmenshan Mountain and the Sichuan Basin,the imbricated structural belt in the hanging-wall thrusted strongly in the Indosinian orogeny and was reactivated in the Himalayan orogeny,while the piedmont buried structural belt in the footwall was formed in the Himalayan orogeny.In the footwall of the frontier fault of thrust nappes,the piedmont buried structural belt has good configuration of source rocks,reservoir rocks and cap rocks,presenting good potential to form large gas reservoirs.In comparison,the hanging-wall of the frontier fault of thrust nappes north of Chonghua has poor condition of oil/gas preservation due to the surface exposure of Triassic and deeper strata,while the fault blocks in the hanging-wall from Chonghua to Wudu,with Jurassic cover and thicker gypsum-salt layer of the Jialingjiang formation,has relative better oil/gas preservation conditions and thus potential of oil/gas accumulation.The frontier fault of thrust nappes is not only the boundary between the Longmenshan Mountain and the Sichuan Basin,but also the boundary of the oil/gas accumulation system in northwestern Sichuan Basin.
文摘胃癌腹膜转移(GCPM)是进展期胃癌常见且致死性高的并发症,中位生存期仅5~11个月。本共识由亚洲30位专家(中国、日本、韩国、新加坡)采用德尔菲法和GRADE证据分级制定,共29条声明,涵盖GCPM诊断评估、腹腔镜探查与NIPS(normothermic intraperitoneal and systemic treatment)适应证、治疗方案、并发症预防管理、转化手术指征及术后腹腔治疗等。共识旨在规范临床实践,提高GCPM预后。
文摘In this paper, a model of two-wave mixing in the photorefractive crystal, which takes account of the difference in spatial frequency in a beam, has been built to study the image enhancement effect in coherent optical amplification. Based on the theoretical analysis of the model, the gain distribution for each pixel in the signal beam has been obtained. It shows that the unevenness of the gain is induced by the difference in spatial frequency in the beam. The factors that impact on the uniformity of image enhancement have been analyzed. As an example, the effects of these factors in a given photorefractive crystal have been studied through simulation.
基金supported by the National Major Science and Technology Project“Enrichment law and target evaluation of large gas fields in Permian-Middle Triassic in Sichuan Basin”(No.:2016ZX05007004)the CNPC Major Science and Technology Project“Study and application of key techniques for 30 billion m^(3)gas production in PetroChina Southwest Oil&Gas Field Company”(No.:2016E-06).
文摘Since 2014,great gas discoveries have been achieved in the Upper Paleozoic Shuangyushi zone in the piedmont zone of the Longmenshan mountains,northwestern Sichuan Basin,where multiple gas wells with industrial flows have been drilled and completed successively in the Middle Permian Qixia Fm and Middle Devonian Guanwushan Fm,etc.Along with the steady progress of exploration there,to make a further in-depth study on the characteristics of the frontal–piedmont zones in the Longmenshan thrust–nappe structures will be of great significance to both a better understanding of Upper Paleozoic gas reservoirs in this study area and the expansion of oil and gas exploration field.In view of this,based on the newly deployed 3D seismic surveys,gravity–magnetic–electronic data,and practical drilling information from exploration wells like Well ST 9,the characteristics of the frontal–piedmont zones in the Longmenshan thrust–nappe structures are analyzed as well as the features of the buried structures,gas reservoir forming conditions and exploration prospect there.The following findings were obtained:(1)A huge buried structure belt is developed underlying the Longmenshan front fault belt No.1(LSFFB 1)and marine strata are thus formed below the Lower Triassic Jialingjiang Fm due to the roles of compressive folding,extrusion and deformation;(2)The detachment horizons from LSFFB 1 go from shallower in the south to deeper in the north,turning from Cambrian slipping in the south to basement-involved in the north.The Paleozoic and its overlying strata were overall uplifted with a higher degree northward and so did the strata between the up-thrown and down-thrown sides of the faults with a greater displacement distance and higher folding degree,resulting in that the Paleozoic strata in the north are 1500 higher uplifted than those in the south;(3)In the western Jiange and Guangyuan areas,the eastern LSFFB 1 presents a tectonic pattern of“three steps”as a whole.In conclusion,there are good gas reservoir forming conditions in LSFFB 1,the down-thrown sides of which cover an area of 1800 km2,where the Guanwushan Fm and Qixia Fm provide good accumulation and preservation conditions for gas reservoirs,which will become favorable gas exploration targets in the deep marine strata in NW Sichuan Basin.
