The main problems in three-dimensional gravity inversion are the non-uniqueness of the solutions and the high computational cost of large data sets. To minimize the high computational cost, we propose a new sorting me...The main problems in three-dimensional gravity inversion are the non-uniqueness of the solutions and the high computational cost of large data sets. To minimize the high computational cost, we propose a new sorting method to reduce fluctuations and the high frequency of the sensitivity matrix prior to applying the wavelet transform. Consequently, the sparsity and compression ratio of the sensitivity matrix are improved as well as the accuracy of the forward modeling. Furthermore, memory storage requirements are reduced and the forward modeling is accelerated compared with uncompressed forward modeling. The forward modeling results suggest that the compression ratio of the sensitivity matrix can be more than 300. Furthermore, multiscale inversion based on the wavelet transform is applied to gravity inversion. By decomposing the gravity inversion into subproblems of different scales, the non-uniqueness and stability of the gravity inversion are improved as multiscale data are considered. Finally, we applied conventional focusing inversion and multiscale inversion on simulated and measured data to demonstrate the effectiveness of the proposed gravity inversion method.展开更多
Hot compression was performed on a multilayered Au−20Sn eutectic alloy to investigate the deformation behavior and microstructure evolution.During hot compression,microstructural spheroidization was initiated from pla...Hot compression was performed on a multilayered Au−20Sn eutectic alloy to investigate the deformation behavior and microstructure evolution.During hot compression,microstructural spheroidization was initiated from plastic instability regions,and it was preferentially activated in vertical lamellae with a growth direction parallel to the compressive direction.Continuous dynamic recrystallization associated with lattice dislocations was the mechanism in both AuSn and Au5Sn multilayers.After spheroidization,strain accumulations were weakened in both of the equiaxed phases,and the deformation mechanism was substantially replaced by grain boundary sliding and migration.Based on these findings,hot rolling was conducted on an as-cast Au−20Sn alloy and a foil with a thickness of~50μm was successfully prepared.The present study can promote the development of Au−20Sn foils,and provide insights into the deformation behavior and microstructure evolution of multilayered eutectic alloys.展开更多
The complex deformation behaviors under tension-compression, cyclic, creep and creep-fatigue loadings of a nickel-base polycrystalline wrought superalloy at 650℃ and 700℃ were experimentally investigated. To uniform...The complex deformation behaviors under tension-compression, cyclic, creep and creep-fatigue loadings of a nickel-base polycrystalline wrought superalloy at 650℃ and 700℃ were experimentally investigated. To uniformly simulate the complex deformation behaviors, the modified viscoplastic constitutive model combined with both the Kachanov damage evolution equation and the Ohno-Wang modification was formulated on the basis of the Chaboche theory. The simulated results on ten-sion-compression behavior, cyclic viscoplastic and creep deformations showed comprehensive predicting ability. With the obtained material parameters, the deformations in creep-fatigue interaction under three dwell types were simulated and the capability of the modified model was further verified with good accuracy.展开更多
基金This work was supported by the Key National Research Project of China （Nos. 2017YFC0601900 and 2016YFC0303100） and the Key Program of National Natural Science Foundation of China （Nos. 41530320 and 41774125）.
文摘The main problems in three-dimensional gravity inversion are the non-uniqueness of the solutions and the high computational cost of large data sets. To minimize the high computational cost, we propose a new sorting method to reduce fluctuations and the high frequency of the sensitivity matrix prior to applying the wavelet transform. Consequently, the sparsity and compression ratio of the sensitivity matrix are improved as well as the accuracy of the forward modeling. Furthermore, memory storage requirements are reduced and the forward modeling is accelerated compared with uncompressed forward modeling. The forward modeling results suggest that the compression ratio of the sensitivity matrix can be more than 300. Furthermore, multiscale inversion based on the wavelet transform is applied to gravity inversion. By decomposing the gravity inversion into subproblems of different scales, the non-uniqueness and stability of the gravity inversion are improved as multiscale data are considered. Finally, we applied conventional focusing inversion and multiscale inversion on simulated and measured data to demonstrate the effectiveness of the proposed gravity inversion method.
基金financial supports from the National Natural Science Foundation of China(Nos.U1502272,51901204)the Precious Metal Materials Genome Engineering in Yunnan Province,China(Nos.2019ZE001,202002AB080001)。
文摘Hot compression was performed on a multilayered Au−20Sn eutectic alloy to investigate the deformation behavior and microstructure evolution.During hot compression,microstructural spheroidization was initiated from plastic instability regions,and it was preferentially activated in vertical lamellae with a growth direction parallel to the compressive direction.Continuous dynamic recrystallization associated with lattice dislocations was the mechanism in both AuSn and Au5Sn multilayers.After spheroidization,strain accumulations were weakened in both of the equiaxed phases,and the deformation mechanism was substantially replaced by grain boundary sliding and migration.Based on these findings,hot rolling was conducted on an as-cast Au−20Sn alloy and a foil with a thickness of~50μm was successfully prepared.The present study can promote the development of Au−20Sn foils,and provide insights into the deformation behavior and microstructure evolution of multilayered eutectic alloys.
基金supported by the National Basic Research Program of China("973"Project)the National Natural Science Foundation of China(Grant No.NSFC 51275023)the Innovation Foundation of BUAA for Ph D Graduates(Grant No.YWF-14-YJSY-49)
文摘The complex deformation behaviors under tension-compression, cyclic, creep and creep-fatigue loadings of a nickel-base polycrystalline wrought superalloy at 650℃ and 700℃ were experimentally investigated. To uniformly simulate the complex deformation behaviors, the modified viscoplastic constitutive model combined with both the Kachanov damage evolution equation and the Ohno-Wang modification was formulated on the basis of the Chaboche theory. The simulated results on ten-sion-compression behavior, cyclic viscoplastic and creep deformations showed comprehensive predicting ability. With the obtained material parameters, the deformations in creep-fatigue interaction under three dwell types were simulated and the capability of the modified model was further verified with good accuracy.
