Reflection-based inversion that aims to reconstruct the low-to-intermediate wavenumbers of the subsurface model, can be a complementary to refraction-data-driven full-waveform inversion(FWI), especially for the deep t...Reflection-based inversion that aims to reconstruct the low-to-intermediate wavenumbers of the subsurface model, can be a complementary to refraction-data-driven full-waveform inversion(FWI), especially for the deep target area where diving waves cannot be acquired at the surface. Nevertheless, as a typical nonlinear inverse problem, reflection waveform inversion may easily suffer from the cycleskipping issue and have a slow convergence rate, if gradient-based first-order optimization methods are used. To improve the accuracy and convergence rate, we introduce the Hessian operator into reflection traveltime inversion(RTI) and reflection waveform inversion(RWI) in the framework of second-order optimization. A practical two-stage workflow is proposed to build the velocity model, in which Gauss-Newton RTI is first applied to mitigate the cycle-skipping problem and then Gauss-Newton RWI is employed to enhance the model resolution. To make the Gauss-Newton iterations more efficiently and robustly for large-scale applications, we introduce proper preconditioning for the Hessian matrix and design appropriate strategies to reduce the computational costs. The example of a real dataset from East China Sea demonstrates that the cascaded Hessian-based RTI and RWI have good potential to improve velocity model building and seismic imaging, especially for the deep targets.展开更多
This paper addresses the Phanerozoic tectonic evolution of the western Tarim Basin based on an integrated stratigraphic,structural and tectonic analysis.P-wave velocity data show that the basin has a stable and rigid ...This paper addresses the Phanerozoic tectonic evolution of the western Tarim Basin based on an integrated stratigraphic,structural and tectonic analysis.P-wave velocity data show that the basin has a stable and rigid basement.The western Tarim Basin experienced a complex tectonic evolutionary history,and this evolution can be divided into six stages:Neoproterozoic to Early Ordovician,Middle Ordovician to Middle Devonian,Late Devonian to Permian,Triassic,Jurassic to Cretaceous and Paleogene to Quaternary.The western Tarim Basin was a rift basin in the Neoproterozoic to Early Ordovician.From the Middle Ordovician to Middle Devonian,the basin consisted of a flexural depression in the south and a depression that changed from a rift depression to a flexural depression in the north during each period,i.e.,the Middle-Late Ordovician and the Silurian to Middle Devonian.During the Late Devonian to Permian,the basin was a depression basin early and then changed into a flexural basin late in each period,i.e.,the Late Devonian to Carboniferous and the Permian.In the Triassic,the basin was a foreland basin,and from the Jurassic to Cretaceous,it was a downwarped basin.After the Paleogene,the basin became a rejuvenated foreland basin.Based on two cross sections,we conclude that the extension and shortening in the profile reflect the tectonic evolution of the Tarim Basin.The Tarim Basin has become a composite and superimposed sedimentary basin because of its long-term and complicated tectonic evolutionary history,highly rigid and stable basement and large size.展开更多
Among the components on a many-core chip, network-on-chip （NoC） has already contributed a large portion to overall power consumption. Optimizing NoC performance under a given power budget is further complicated to k...Among the components on a many-core chip, network-on-chip （NoC） has already contributed a large portion to overall power consumption. Optimizing NoC performance under a given power budget is further complicated to keep the network connectivity and minimize the detour distances. In this paper, a NoC power budgeting method from the communication perspective is proposed, which intelligently powers off routers/iinks and sets up alternative paths to restrict the power and thermal envelop. The effect of performance optimizaion of the proposed power budgeting mothod is measured based on latency and in the given power budget, 22% latency can be reduced averagely compared with some competing methods when running real benchmarks.展开更多
基金supported by National Natural Science Foundation of China (42074157)the National Key Research and Development Program of China (2018YFC0310104)the Strategic Priority Research Program of the Chinese Academy of Science(XDA14010203)。
文摘Reflection-based inversion that aims to reconstruct the low-to-intermediate wavenumbers of the subsurface model, can be a complementary to refraction-data-driven full-waveform inversion(FWI), especially for the deep target area where diving waves cannot be acquired at the surface. Nevertheless, as a typical nonlinear inverse problem, reflection waveform inversion may easily suffer from the cycleskipping issue and have a slow convergence rate, if gradient-based first-order optimization methods are used. To improve the accuracy and convergence rate, we introduce the Hessian operator into reflection traveltime inversion(RTI) and reflection waveform inversion(RWI) in the framework of second-order optimization. A practical two-stage workflow is proposed to build the velocity model, in which Gauss-Newton RTI is first applied to mitigate the cycle-skipping problem and then Gauss-Newton RWI is employed to enhance the model resolution. To make the Gauss-Newton iterations more efficiently and robustly for large-scale applications, we introduce proper preconditioning for the Hessian matrix and design appropriate strategies to reduce the computational costs. The example of a real dataset from East China Sea demonstrates that the cascaded Hessian-based RTI and RWI have good potential to improve velocity model building and seismic imaging, especially for the deep targets.
基金supported by the China Postdoctoral Science Foundation(No.2019M650960)the Petro-China Tarim Oilfield Company(No.041011080018).
文摘This paper addresses the Phanerozoic tectonic evolution of the western Tarim Basin based on an integrated stratigraphic,structural and tectonic analysis.P-wave velocity data show that the basin has a stable and rigid basement.The western Tarim Basin experienced a complex tectonic evolutionary history,and this evolution can be divided into six stages:Neoproterozoic to Early Ordovician,Middle Ordovician to Middle Devonian,Late Devonian to Permian,Triassic,Jurassic to Cretaceous and Paleogene to Quaternary.The western Tarim Basin was a rift basin in the Neoproterozoic to Early Ordovician.From the Middle Ordovician to Middle Devonian,the basin consisted of a flexural depression in the south and a depression that changed from a rift depression to a flexural depression in the north during each period,i.e.,the Middle-Late Ordovician and the Silurian to Middle Devonian.During the Late Devonian to Permian,the basin was a depression basin early and then changed into a flexural basin late in each period,i.e.,the Late Devonian to Carboniferous and the Permian.In the Triassic,the basin was a foreland basin,and from the Jurassic to Cretaceous,it was a downwarped basin.After the Paleogene,the basin became a rejuvenated foreland basin.Based on two cross sections,we conclude that the extension and shortening in the profile reflect the tectonic evolution of the Tarim Basin.The Tarim Basin has become a composite and superimposed sedimentary basin because of its long-term and complicated tectonic evolutionary history,highly rigid and stable basement and large size.
基金supported by the National Natural Science Foundation of China under Grant No.61376024 and No.61306024Natural Science Foundation of Guangdong Province under Grant No.S2013040014366Basic Research Programme of Shenzhen No.JCYJ20140417113430642 and No.JCYJ20140901003939020
文摘Among the components on a many-core chip, network-on-chip （NoC） has already contributed a large portion to overall power consumption. Optimizing NoC performance under a given power budget is further complicated to keep the network connectivity and minimize the detour distances. In this paper, a NoC power budgeting method from the communication perspective is proposed, which intelligently powers off routers/iinks and sets up alternative paths to restrict the power and thermal envelop. The effect of performance optimizaion of the proposed power budgeting mothod is measured based on latency and in the given power budget, 22% latency can be reduced averagely compared with some competing methods when running real benchmarks.
