Background Image matching is crucial in numerous computer vision tasks such as 3D reconstruction and simultaneous visual localization and mapping.The accuracy of the matching significantly impacted subsequent studies....Background Image matching is crucial in numerous computer vision tasks such as 3D reconstruction and simultaneous visual localization and mapping.The accuracy of the matching significantly impacted subsequent studies.Because of their local similarity,when image pairs contain comparable patterns but feature pairs are positioned differently,incorrect recognition can occur as global motion consistency is disregarded.Methods This study proposes an image-matching filtering algorithm based on global motion consistency.It can be used as a subsequent matching filter for the initial matching results generated by other matching algorithms based on the principle of motion smoothness.A particular matching algorithm can first be used to perform the initial matching;then,the rotation and movement information of the global feature vectors are combined to effectively identify outlier matches.The principle is that if the matching result is accurate,the feature vectors formed by any matched point should have similar rotation angles and moving distances.Thus,global motion direction and global motion distance consistencies were used to reject outliers caused by similar patterns in different locations.Results Four datasets were used to test the effectiveness of the proposed method.Three datasets with similar patterns in different locations were used to test the results for similar images that could easily be incorrectly matched by other algorithms,and one commonly used dataset was used to test the results for the general image-matching problem.The experimental results suggest that the proposed method is more accurate than other state-of-the-art algorithms in identifying mismatches in the initial matching set.Conclusions The proposed outlier rejection matching method can significantly improve the matching accuracy for similar images with locally similar feature pairs in different locations and can provide more accurate matching results for subsequent computer vision tasks.展开更多
Global failure mechanism, i.e., the strong-column weak-beam mechanism, can provide higher total energy dissipation capacity with less ductility demand on components than other failure modes, and results in a more unif...Global failure mechanism, i.e., the strong-column weak-beam mechanism, can provide higher total energy dissipation capacity with less ductility demand on components than other failure modes, and results in a more uniform story drift distribution and higher resistance to earthquake loads at the system level. However, the current code-based elastic design method cannot guarantee the global failure mechanism of frame structures under severe earthquakes. In this paper, a simple, but practical design procedure is proposed to ensure the global failure mechanism of reinforced concrete(RC) frame structures by redesigning the columns using the column tree method(CTM). CTM considers the yield limit state of all beams and column bases. The code-based design is firstly carried out to determine the section information of all beams and base columns. Then, the internal force demands applied on the column tree can be derived. Lastly, the column moments, shear forces and axial forces are determined according to the free-body diagram of CTM to finish the column redesign. Two RC frame structures with 6 and 12 stories are illustrated to verify the design procedure. The analytical results demonstrate the proposed approach can realize the global failure mechanism.展开更多
Recently, we proved the Griffiths conjecture on the boundedness of the period maps, and then used it to prove global Torelli theorem on the Torelli space under certain natural conditions. This paper serves as a review...Recently, we proved the Griffiths conjecture on the boundedness of the period maps, and then used it to prove global Torelli theorem on the Torelli space under certain natural conditions. This paper serves as a review of these results and an introduction to the main ideas behind the proofs.展开更多
At present, there are no criteria to distinguish soft-sediment deformation structures （SSDS） formed by earthquakes from SSDS formed by the other 20 triggering mechanisms （see a companion paper in Vol 5, No. 4 of th...At present, there are no criteria to distinguish soft-sediment deformation structures （SSDS） formed by earthquakes from SSDS formed by the other 20 triggering mechanisms （see a companion paper in Vol 5, No. 4 of this journal by Shanmugam, 2016）. Even if one betieves that earthquakes are the true triggering mechanism of SSDS in a given case, the story is stiff incomptete. This is because earthquakes （seismic shocks） are induced by a variety of causes： 1） glbaltectonics and associated faults （i.e., midocean ridges, trenches, and transform fautts）; 2） meteorite-impact events; 3） volcanic eruptions; 4） post-gtacialuplift; 5） tsunami impact; 6 cyclonic impact; 7） landslides （mass-transport deposits）; 8） tidal activity; 9） sea-tevet rise; 10） erosion; and 11） fluid pumping. These different causes are important for devetoping SSDS. Breccias are an important group of SSDS. Although there are many types of breccias classified on the basis of their origin, five types are discussed here （fault, volcanic, meteorite impact, sedimentary-depositionaL, sedimentary-collapse）. Atthough different breccia types may resemble each other, distinguishing one type （e.g., meteorite breccias） from the other types （e.g., fault, volcanic, and sedimentary breccias） has important imptications. 1） Meteorite breccias are characterized by shock features （e.g., planar deformation features in mineral grains, planar fractures, high-pressure polymorphs, shock melts, etc.）, whereas sedimentary- depositional breccias （e.g., debrites） do not. 2） Meteorite breccias imply a confined sediment distribution in the vicinity of craters, whereas sedimentary-depositional breccias imply an unconfined sediment distribution, variable sediment transport, and variable sediment provenance. 3） Meteorite, volcanic, and fault breccias are invariabty subjected to diagenesis and hydrothermat mineratization with attered reservoir quality, whereas sedimentary-depositional breccias exhibit primary （unaltere展开更多
基金Supported by the Natural Science Foundation of China(62072388,62276146)the Industry Guidance Project Foundation of Science technology Bureau of Fujian province(2020H0047)+2 种基金the Natural Science Foundation of Science Technology Bureau of Fujian province(2019J01601)the Creation Fund project of Science Technology Bureau of Fujian province(JAT190596)Putian University Research Project(2022034)。
文摘Background Image matching is crucial in numerous computer vision tasks such as 3D reconstruction and simultaneous visual localization and mapping.The accuracy of the matching significantly impacted subsequent studies.Because of their local similarity,when image pairs contain comparable patterns but feature pairs are positioned differently,incorrect recognition can occur as global motion consistency is disregarded.Methods This study proposes an image-matching filtering algorithm based on global motion consistency.It can be used as a subsequent matching filter for the initial matching results generated by other matching algorithms based on the principle of motion smoothness.A particular matching algorithm can first be used to perform the initial matching;then,the rotation and movement information of the global feature vectors are combined to effectively identify outlier matches.The principle is that if the matching result is accurate,the feature vectors formed by any matched point should have similar rotation angles and moving distances.Thus,global motion direction and global motion distance consistencies were used to reject outliers caused by similar patterns in different locations.Results Four datasets were used to test the effectiveness of the proposed method.Three datasets with similar patterns in different locations were used to test the results for similar images that could easily be incorrectly matched by other algorithms,and one commonly used dataset was used to test the results for the general image-matching problem.The experimental results suggest that the proposed method is more accurate than other state-of-the-art algorithms in identifying mismatches in the initial matching set.Conclusions The proposed outlier rejection matching method can significantly improve the matching accuracy for similar images with locally similar feature pairs in different locations and can provide more accurate matching results for subsequent computer vision tasks.
基金supported by the National Natural Science Foundation of China(Grant Nos.51261120376 and 91315301)Scholarship Award for Excellent Doctoral Student granted by Ministry of Education of China
文摘Global failure mechanism, i.e., the strong-column weak-beam mechanism, can provide higher total energy dissipation capacity with less ductility demand on components than other failure modes, and results in a more uniform story drift distribution and higher resistance to earthquake loads at the system level. However, the current code-based elastic design method cannot guarantee the global failure mechanism of frame structures under severe earthquakes. In this paper, a simple, but practical design procedure is proposed to ensure the global failure mechanism of reinforced concrete(RC) frame structures by redesigning the columns using the column tree method(CTM). CTM considers the yield limit state of all beams and column bases. The code-based design is firstly carried out to determine the section information of all beams and base columns. Then, the internal force demands applied on the column tree can be derived. Lastly, the column moments, shear forces and axial forces are determined according to the free-body diagram of CTM to finish the column redesign. Two RC frame structures with 6 and 12 stories are illustrated to verify the design procedure. The analytical results demonstrate the proposed approach can realize the global failure mechanism.
文摘Recently, we proved the Griffiths conjecture on the boundedness of the period maps, and then used it to prove global Torelli theorem on the Torelli space under certain natural conditions. This paper serves as a review of these results and an introduction to the main ideas behind the proofs.
文摘At present, there are no criteria to distinguish soft-sediment deformation structures （SSDS） formed by earthquakes from SSDS formed by the other 20 triggering mechanisms （see a companion paper in Vol 5, No. 4 of this journal by Shanmugam, 2016）. Even if one betieves that earthquakes are the true triggering mechanism of SSDS in a given case, the story is stiff incomptete. This is because earthquakes （seismic shocks） are induced by a variety of causes： 1） glbaltectonics and associated faults （i.e., midocean ridges, trenches, and transform fautts）; 2） meteorite-impact events; 3） volcanic eruptions; 4） post-gtacialuplift; 5） tsunami impact; 6 cyclonic impact; 7） landslides （mass-transport deposits）; 8） tidal activity; 9） sea-tevet rise; 10） erosion; and 11） fluid pumping. These different causes are important for devetoping SSDS. Breccias are an important group of SSDS. Although there are many types of breccias classified on the basis of their origin, five types are discussed here （fault, volcanic, meteorite impact, sedimentary-depositionaL, sedimentary-collapse）. Atthough different breccia types may resemble each other, distinguishing one type （e.g., meteorite breccias） from the other types （e.g., fault, volcanic, and sedimentary breccias） has important imptications. 1） Meteorite breccias are characterized by shock features （e.g., planar deformation features in mineral grains, planar fractures, high-pressure polymorphs, shock melts, etc.）, whereas sedimentary- depositional breccias （e.g., debrites） do not. 2） Meteorite breccias imply a confined sediment distribution in the vicinity of craters, whereas sedimentary-depositional breccias imply an unconfined sediment distribution, variable sediment transport, and variable sediment provenance. 3） Meteorite, volcanic, and fault breccias are invariabty subjected to diagenesis and hydrothermat mineratization with attered reservoir quality, whereas sedimentary-depositional breccias exhibit primary （unaltere
