Wide angle acquisition has been taken as a significant measure to obtain high quality seismic data and is getting greater attention, In this paper, we discuss ocean bottom cable （OBC） seismic wide angle reflections ...Wide angle acquisition has been taken as a significant measure to obtain high quality seismic data and is getting greater attention, In this paper, we discuss ocean bottom cable （OBC） seismic wide angle reflections on the basis of a layered model experiment. Some experiment results don＇t support theoretical conclusions. The main experimental conclusions are： 1. Wide angle reflection energies are stronger than non-wide-angle reflections （up to twice as strong） but there is a big difference between observations and theoretical calculations that suggest the wide angle reflection energies are 15 times the non- wide-angle reflection energy. The reflection energy increases gradually rather than sharply as the theoretical calculations suggest. 2. The reflection events remain hyperbolic when the offset increases. 3. Wide angle reflection dominant frequency is about 20-30% less than non- wide-angle reflections and decreases as the offset increases. The non-wide-angle reflection dominant frequency shows no obvious variation for small offsets. 4. There is no wave shape mutation or polarity reversal near the critical angle. 5. The reflection event group features are the same for both cases of incidence angle greater and less than the critical angle. 6. Direct arrivals, multiples, and water bottom refractions influence the wide angle reflections of the sea floor.展开更多
In 2018,a catastrophic high-altitude landslide occurred at Baige,located within the tectonic suture zone of the Upper Jinsha River.The failure mechanism of this event remains poorly understood.This study aims to eluci...In 2018,a catastrophic high-altitude landslide occurred at Baige,located within the tectonic suture zone of the Upper Jinsha River.The failure mechanism of this event remains poorly understood.This study aims to elucidate the deformation characteristics and failure mechanism of the Baige landslide by employing a comprehensive methodology,including field geological surveys,analysis of historical remote sensing imagery,high-density electrical resistivity surveys,and advanced displacement monitoring.Additionally,the physical modeling experiments were conducted to replicate the unique failure modes.The findings propose a novel perspective on the failure mechanism of the Baige landslide,which involves two critical stages:first,the brittle shear zone bypasses and fails at the lower locked segment,and second,the failure of the upper locked segment,combined with the shear zone's impact on the lower locked segment,triggers overall slope instability.Physical modeling experiments revealed a transition from initial acceleration to a rapid acceleration phase,particularly marked by a significant increase in velocity following the failure of the upper locked segment.The intensity of acoustic emission signals was found to correlate with the failure of the locked segments and the state of particle collisions post-failure.It offers new insights into the failure mechanisms of tectonic mélange belt large-scale landslides in suture zones,contributing to the broader field of landslide research.展开更多
Based on the existing Land Surface Physical Process Models(Deardorff, Dickinson, LIU, Noilhan, Seller, ZHAO), a Comprehensive Land Surface Physical Process Model (CLSPPM) is developed by considering the different phys...Based on the existing Land Surface Physical Process Models(Deardorff, Dickinson, LIU, Noilhan, Seller, ZHAO), a Comprehensive Land Surface Physical Process Model (CLSPPM) is developed by considering the different physical processes of the earth's surface-vegetation-atmosphere system more completely. Compared with SiB and BATS, which are famous for their detailed parameterizations of physical variables, this simplified model is more convenient and saves much more computation time. Though simple, the feas...展开更多
A modified version of the NCAR/RegCM2 has been developed at the National Climate Center （NCC）, China Meteorological Administration, through a series of sensitivity experiments and multi-year simulations and hindcast...A modified version of the NCAR/RegCM2 has been developed at the National Climate Center （NCC）, China Meteorological Administration, through a series of sensitivity experiments and multi-year simulations and hindcasts, with a special emphasis on the adequate choice of physical parameterization schemes suitable for the East Asian monsoon climate. This regional climate model is nested with the NCC/IAP （Institute of Atmospheric Physics） T63 coupled GCM to make an experimental seasonal prediction for China and East Asia. The four-year （2001 to 2004） prediction results are encouraging. This paper is the first part of a two-part paper, and it mainly describes the sensitivity study of the physical process paraxneterization represented in the model. The systematic errors produced by the different physical parameterization schemes such as the land surface processes, convective precipitation, cloud-radiation transfer process, boundary layer process and large-scale terrain features have been identified based on multi-year and extreme flooding event simulations. A number of comparative experiments has shown that the mass flux scheme （MFS） and Betts-Miller scheme （BM） for convective precipitation, the LPMI （land surface process model I） and LPMII （land surface process model Ⅱ） for the land surface process, the CCM3 radiation transfer scheme for cloud-radiation transfer processes, the TKE （turbulent kinetic energy） scheme for the boundary layer processes and the topography treatment schemes for the Tibetan Plateau are suitable for simulations and prediction of the East Asia monsoon climate in rainy seasons. Based on the above sensitivity study, a modified version of the RegCM2 （RegCM_NCC） has been set up for climate simulations and seasonal predictions.展开更多
The electrophysical property of saturated rocks is very important for reservoir identification and evaluation. In this paper, the lattice Boltzmann method （LBM） was used to study the electrophysical property of rock...The electrophysical property of saturated rocks is very important for reservoir identification and evaluation. In this paper, the lattice Boltzmann method （LBM） was used to study the electrophysical property of rock saturated with fluid because of its advantages over conventional numerical approaches in handling complex pore geometry and boundary conditions. The digital core model was constructed through the accumulation of matrix grains based on their radius distribution obtained by the measurements of core samples. The flow of electrical current through the core model saturated with oil and water was simulated on the mesoscopic scale to reveal the non-Archie relationship between resistivity index and water saturation （I-Sw）. The results from LBM simulation and laboratory measurements demonstrated that the I-Sw relation in the range of low water saturation was generally not a straight line in the log-log coordinates as described by the Archie equation. We thus developed a new equation based on numerical simulation and physical experiments. This new equation was used to fit the data from laboratory core measurements and previously published data. Determination of fluid saturation and reservoir evaluation could be significantly improved by using the new equation.展开更多
The western fault zone of the South China Sea is a strike-slip fault system and consists of four typical strike-slip faults. It is the western border of the South China Sea. The formation of the system is due to the e...The western fault zone of the South China Sea is a strike-slip fault system and consists of four typical strike-slip faults. It is the western border of the South China Sea. The formation of the system is due to the extrusion of Indo - China Peninsula caused by the collision of India with Tibet and the spreading of the South China Sea in Cenozoic. There are five episodes of tectonic movement along this fault zone, which plays an important role in the Cenozoic evolution of the South China Sea. By the physical modeling experiments, it can be seen the strike-slip fault undergoes the sinistral and dextral movement due to the relative movement velocity change between the South China Sea block and the Indo - China block. The fault zone controls the evolution of the pull basins locating in the west of the South China Sea.展开更多
Fishing boats are usually anchored side by side in the harbor because of the small structural size and poor resistance to wind and waves.A series of physical model experiments are conducted to investigate the motion c...Fishing boats are usually anchored side by side in the harbor because of the small structural size and poor resistance to wind and waves.A series of physical model experiments are conducted to investigate the motion characteristics of multiple fishing boats that are moored together.A decay test in calm water is conducted to study the natural period and damping coefficients.Regular wave experiments are performed to analyze the roll motion response of each boat for four modes(different numbers of boats side-by-side).The results indicate that the“natural period”of each boat for the mode of multi-boats especially three or four boats,is slightly smaller than that of a single boat,whereas the damping coefficient is visibly larger than that of a single boat.The maximum roll angle of each boat does not appear at the same time under a 90°incident wave.Small roll motion energy is generated at low frequencies and high frequencies when multiple boats are moored together.The energy decreases with the increasing wave period.The roll motion responses of each boat in four modes exhibit different trends with the increasing wave frequency.The number of boats and boat position have significant effects on roll motion.展开更多
In this paper,the dynamic response characteristics of an ancient shipwreck“ChangJiangKou II”salvaging system during its salvaging operation,including off-bottom,lifting and off-surface stage,are numerically and expe...In this paper,the dynamic response characteristics of an ancient shipwreck“ChangJiangKou II”salvaging system during its salvaging operation,including off-bottom,lifting and off-surface stage,are numerically and experimentally investigated.In order to accurately predict the hydrodynamic performance of“ChangJiangKou II”and the crane barge during the salvaging operation,a specific designed coupled time-domain model combining wreck-soil interaction,lifting module and mooring module is established.A physical model-scale experiment for dynamic lifting of an underwater structure is performed to validate the coupled numerical model.The performance of the dynamic lifting process in different lifting speeds and different environmental conditions is analysed and discussed.The experimental results indicate that there is a tension distribution process during the lifting operation and an external disturbance to the shipwreck can lead to a large increase in lifting cable tensions.展开更多
To address the problems of difficult leveling and poor stability of hill crawler tractors,an attitude adjustment device based on a parallel four-bar mechanism was designed,and the mechanical reasons for the sideslip i...To address the problems of difficult leveling and poor stability of hill crawler tractors,an attitude adjustment device based on a parallel four-bar mechanism was designed,and the mechanical reasons for the sideslip instability of hill crawler tractors were analyzed.On this basis,a posture adjustment mechanism based on a parallel four-bar mechanism was proposed,and the structure of the complete attitude adjustment device was designed.To ensure that this device meets the strength requirements during operation,a mechanical analysis of the key components(active rocker and slave rocker)was carried out to accommodate the load during leveling.Based on ANSYS software,a finite element simulation analysis was used to determine the maximum stress position of the active and slave rockers.Finally,to verify the accuracy of the above simulation analysis results and determine the influence rules of the lateral slope angle,longitudinal slope angle and loading quality on the abovementioned maximum stress,a physical model test bench of the attitude adjustment device was built.An orthogonal regression experiment was carried out with the maximum stresses of the active and slave rockers as the test indices.The experimental data were analyzed by Design-Expert 10 software,and the results show that the order of the primary and secondary factors influencing the maximum stress of the active rocker was the loading mass,lateral slope angle and longitudinal slope angle.The order of the factors influencing the maximum stress of the slave rocker was the longitudinal slope angle,lateral slope angle and loading mass.The active and slave rockers meet the strength requirements.This work provides technical support for the production of hill crawler tractor physical prototypes.展开更多
文摘Wide angle acquisition has been taken as a significant measure to obtain high quality seismic data and is getting greater attention, In this paper, we discuss ocean bottom cable （OBC） seismic wide angle reflections on the basis of a layered model experiment. Some experiment results don＇t support theoretical conclusions. The main experimental conclusions are： 1. Wide angle reflection energies are stronger than non-wide-angle reflections （up to twice as strong） but there is a big difference between observations and theoretical calculations that suggest the wide angle reflection energies are 15 times the non- wide-angle reflection energy. The reflection energy increases gradually rather than sharply as the theoretical calculations suggest. 2. The reflection events remain hyperbolic when the offset increases. 3. Wide angle reflection dominant frequency is about 20-30% less than non- wide-angle reflections and decreases as the offset increases. The non-wide-angle reflection dominant frequency shows no obvious variation for small offsets. 4. There is no wave shape mutation or polarity reversal near the critical angle. 5. The reflection event group features are the same for both cases of incidence angle greater and less than the critical angle. 6. Direct arrivals, multiples, and water bottom refractions influence the wide angle reflections of the sea floor.
基金supported by the National Major Scientific Instruments and Equipment Development Projects of China(No.41827808)the Major Program of the National Natural Science Foundation of China(No.42090055)Supported by Science and Technology Projects of Xizang Autonomous Region,China(No.XZ202402ZD0001)。
文摘In 2018,a catastrophic high-altitude landslide occurred at Baige,located within the tectonic suture zone of the Upper Jinsha River.The failure mechanism of this event remains poorly understood.This study aims to elucidate the deformation characteristics and failure mechanism of the Baige landslide by employing a comprehensive methodology,including field geological surveys,analysis of historical remote sensing imagery,high-density electrical resistivity surveys,and advanced displacement monitoring.Additionally,the physical modeling experiments were conducted to replicate the unique failure modes.The findings propose a novel perspective on the failure mechanism of the Baige landslide,which involves two critical stages:first,the brittle shear zone bypasses and fails at the lower locked segment,and second,the failure of the upper locked segment,combined with the shear zone's impact on the lower locked segment,triggers overall slope instability.Physical modeling experiments revealed a transition from initial acceleration to a rapid acceleration phase,particularly marked by a significant increase in velocity following the failure of the upper locked segment.The intensity of acoustic emission signals was found to correlate with the failure of the locked segments and the state of particle collisions post-failure.It offers new insights into the failure mechanisms of tectonic mélange belt large-scale landslides in suture zones,contributing to the broader field of landslide research.
基金National Natural Science Foundation of China (No. 40275004)State Key Laboratory of Atmosphere Physics and Chemistry
文摘Based on the existing Land Surface Physical Process Models(Deardorff, Dickinson, LIU, Noilhan, Seller, ZHAO), a Comprehensive Land Surface Physical Process Model (CLSPPM) is developed by considering the different physical processes of the earth's surface-vegetation-atmosphere system more completely. Compared with SiB and BATS, which are famous for their detailed parameterizations of physical variables, this simplified model is more convenient and saves much more computation time. Though simple, the feas...
文摘A modified version of the NCAR/RegCM2 has been developed at the National Climate Center （NCC）, China Meteorological Administration, through a series of sensitivity experiments and multi-year simulations and hindcasts, with a special emphasis on the adequate choice of physical parameterization schemes suitable for the East Asian monsoon climate. This regional climate model is nested with the NCC/IAP （Institute of Atmospheric Physics） T63 coupled GCM to make an experimental seasonal prediction for China and East Asia. The four-year （2001 to 2004） prediction results are encouraging. This paper is the first part of a two-part paper, and it mainly describes the sensitivity study of the physical process paraxneterization represented in the model. The systematic errors produced by the different physical parameterization schemes such as the land surface processes, convective precipitation, cloud-radiation transfer process, boundary layer process and large-scale terrain features have been identified based on multi-year and extreme flooding event simulations. A number of comparative experiments has shown that the mass flux scheme （MFS） and Betts-Miller scheme （BM） for convective precipitation, the LPMI （land surface process model I） and LPMII （land surface process model Ⅱ） for the land surface process, the CCM3 radiation transfer scheme for cloud-radiation transfer processes, the TKE （turbulent kinetic energy） scheme for the boundary layer processes and the topography treatment schemes for the Tibetan Plateau are suitable for simulations and prediction of the East Asia monsoon climate in rainy seasons. Based on the above sensitivity study, a modified version of the RegCM2 （RegCM_NCC） has been set up for climate simulations and seasonal predictions.
基金sponsored by the project No.50404001 from the National Natural Science Foundation of Chinathe National Key Fundamental Research & Development Project(Grant No.2007CB209601)+1 种基金the China National PetroleumCorporation Fundamental Research Program (Grant No.06A30102)the China Postdoctoral Science Foundation(Project No.2004035350)
文摘The electrophysical property of saturated rocks is very important for reservoir identification and evaluation. In this paper, the lattice Boltzmann method （LBM） was used to study the electrophysical property of rock saturated with fluid because of its advantages over conventional numerical approaches in handling complex pore geometry and boundary conditions. The digital core model was constructed through the accumulation of matrix grains based on their radius distribution obtained by the measurements of core samples. The flow of electrical current through the core model saturated with oil and water was simulated on the mesoscopic scale to reveal the non-Archie relationship between resistivity index and water saturation （I-Sw）. The results from LBM simulation and laboratory measurements demonstrated that the I-Sw relation in the range of low water saturation was generally not a straight line in the log-log coordinates as described by the Archie equation. We thus developed a new equation based on numerical simulation and physical experiments. This new equation was used to fit the data from laboratory core measurements and previously published data. Determination of fluid saturation and reservoir evaluation could be significantly improved by using the new equation.
基金Acknowledgements This research was supported by the National Natural Science Foundation of China under contract Nos 40476026 and 40406012, the National Natural Science Foundation of Guangdong Province under contract No. 04001309, and the Key Laboratory of Marginal Sea Geology Foundation of South China Sea Institute of 0ceanology, Chinese Academy of Sciences under contract No. MSGL0510. We are grateful to Yan Pin and Liu Hailing for their generous help in providing seismic profiles.
文摘The western fault zone of the South China Sea is a strike-slip fault system and consists of four typical strike-slip faults. It is the western border of the South China Sea. The formation of the system is due to the extrusion of Indo - China Peninsula caused by the collision of India with Tibet and the spreading of the South China Sea in Cenozoic. There are five episodes of tectonic movement along this fault zone, which plays an important role in the Cenozoic evolution of the South China Sea. By the physical modeling experiments, it can be seen the strike-slip fault undergoes the sinistral and dextral movement due to the relative movement velocity change between the South China Sea block and the Indo - China block. The fault zone controls the evolution of the pull basins locating in the west of the South China Sea.
基金financially supported by Central Public-interest Scientific Institution Basal Research Fund,CAFS(Grant Nos.2023TD88,2024HY-ZC005,and 2024XT0801).
文摘Fishing boats are usually anchored side by side in the harbor because of the small structural size and poor resistance to wind and waves.A series of physical model experiments are conducted to investigate the motion characteristics of multiple fishing boats that are moored together.A decay test in calm water is conducted to study the natural period and damping coefficients.Regular wave experiments are performed to analyze the roll motion response of each boat for four modes(different numbers of boats side-by-side).The results indicate that the“natural period”of each boat for the mode of multi-boats especially three or four boats,is slightly smaller than that of a single boat,whereas the damping coefficient is visibly larger than that of a single boat.The maximum roll angle of each boat does not appear at the same time under a 90°incident wave.Small roll motion energy is generated at low frequencies and high frequencies when multiple boats are moored together.The energy decreases with the increasing wave period.The roll motion responses of each boat in four modes exhibit different trends with the increasing wave frequency.The number of boats and boat position have significant effects on roll motion.
基金support of National Key Research and Development Program of China(Grant No.2023YFC2809801)the National Natural Science Foundation of China(Grant No.42406205)Opening Foundation of State Key Laboratory of Maritime Technology and Safety(Grant No.W24CG000040).
文摘In this paper,the dynamic response characteristics of an ancient shipwreck“ChangJiangKou II”salvaging system during its salvaging operation,including off-bottom,lifting and off-surface stage,are numerically and experimentally investigated.In order to accurately predict the hydrodynamic performance of“ChangJiangKou II”and the crane barge during the salvaging operation,a specific designed coupled time-domain model combining wreck-soil interaction,lifting module and mooring module is established.A physical model-scale experiment for dynamic lifting of an underwater structure is performed to validate the coupled numerical model.The performance of the dynamic lifting process in different lifting speeds and different environmental conditions is analysed and discussed.The experimental results indicate that there is a tension distribution process during the lifting operation and an external disturbance to the shipwreck can lead to a large increase in lifting cable tensions.
基金This research was conducted at the College of Mechanical and Electronic Engineering,Northwest A&F University and was supported by the National Key Research and Development Plan Program(2016YFD0700503).
文摘To address the problems of difficult leveling and poor stability of hill crawler tractors,an attitude adjustment device based on a parallel four-bar mechanism was designed,and the mechanical reasons for the sideslip instability of hill crawler tractors were analyzed.On this basis,a posture adjustment mechanism based on a parallel four-bar mechanism was proposed,and the structure of the complete attitude adjustment device was designed.To ensure that this device meets the strength requirements during operation,a mechanical analysis of the key components(active rocker and slave rocker)was carried out to accommodate the load during leveling.Based on ANSYS software,a finite element simulation analysis was used to determine the maximum stress position of the active and slave rockers.Finally,to verify the accuracy of the above simulation analysis results and determine the influence rules of the lateral slope angle,longitudinal slope angle and loading quality on the abovementioned maximum stress,a physical model test bench of the attitude adjustment device was built.An orthogonal regression experiment was carried out with the maximum stresses of the active and slave rockers as the test indices.The experimental data were analyzed by Design-Expert 10 software,and the results show that the order of the primary and secondary factors influencing the maximum stress of the active rocker was the loading mass,lateral slope angle and longitudinal slope angle.The order of the factors influencing the maximum stress of the slave rocker was the longitudinal slope angle,lateral slope angle and loading mass.The active and slave rockers meet the strength requirements.This work provides technical support for the production of hill crawler tractor physical prototypes.
